Chapter II Mill's Logic I. Intuitionism and Empiricism Mill's System of Logic may be regarded as the most important manifesto of Utilitarian philosophy. It lays down explicitly and in their ripest form the principles implicitly assumed by Bentham and the elder Mill. It modifies as well as expounds. It represents the process by which J. S. Mill, on becoming aware of certain defects in the Utilitarians' philosophy, endeavoured to restate the first principles so as to avoid the erroneous conclusions. The coincidence with his predecessors remains far closer than the divergence. The fundamental tenets are developed rather than withdrawn. The Logic thus most distinctly raises the ultimate issues. It has the impressiveness which belongs in some degree to every genuine exertion of a powerful mind. Mill is struggling with real difficulties; not trying to bolster up a theory commended to him by extraneous considerations. He is doing his best to give an answer to his problem; not to hide an evasion. His honourable candour incidentally reveals the weakness as frankly as the strength of his position. He neither shirks nor hides difficulties, and if we are forced to admit that some of his reasoning is fallacious, the admission scarcely adds to the statement that he is writing a treatise upon philosophical problems. His frankness has made the task of critics comparatively easy. It takes so many volumes to settle what some philosophers have meant that we scarcely reach the question whether their meaning, or rather any of their many possible meanings, was right. In the case of Mill, that preparatory labour is not required. His book, too, has been sufficiently tested by time to enable us to mark the points at which his structure has failed to stand the wear and tear of general discussion. I must try to bring out the vital points of the doctrine. Mill, I have said, had a very definite purpose beyond the purely philosophical. 'Bad institutions,' he says,(1*) are supported by false philosophy. The false philosophy to which he refers is that of the so-called 'intuitionist school.' Its 'stronghold,' he thought, lay in appeals to the mathematical and physical sciences. To drive it from this position was to deprive it of 'speculative support'; and, though it could still appeal to prejudice, the destruction of this support was an indispenSable step to complete victory. Mill wished to provide a logical armoury for all assailants of established dogmatism, and his success as a propagandist surprised him. The book was read, to his astonishment, even in the universities. Indeed, I can testify from personal observation that it became a kind of sacred book for students who claimed to be genuine Liberals. It gave the philosophical creed of an important section of the rising generation, partly biassed, it may be, by the application to 'bad institutions.' Mill's logic, that is, fell in with the one main current of political opinion. His readings in logic with Grote and other friends enabled him to fashion the weapons needed for the assault. Thus in its origin and by its execution the task was in fact an attempt to give an organised statement of sound philosophy in a form applicable to social and political speculations. Mill considered that the school of metaphysicians which he attacked had long predominated in this country.(2*) When Taine called his view specially English, Mill protested. The Scottish reaction against Hume, he said, which 'assumed long ago the German form,' had ended by 'prevailing universally' in this country. When he first wrote he was almost alone in his opinions, and there were still 'twenty a priori and spiritualist philosophers for every partisan of the doctrine of Experience.'(3*) The philosophical world, he says elsewhere,(4*) is 'bisected' by the line between the 'Intuitional' and the 'Experiential' schools. Mill's conviction that a majority of Englishmen were really 'intuitionists' in any shape is significant, I think, of his isolated position. Undoubtedly most Englishmen disliked Utilitarians, and respectable professors of philosophy were anxious to disavow sympathy with covert atheism. Yet the general tendency of thought was, I suspect, far more congenial to Mill's doctrine than he admitted. Englishmen were practically, if not avowedly, predisposed to empiricism. In any case, he was carrying on the tradition which Taine rightly, as I should say, regarded as specifically English. Its adherents traced its origin back through James Mill to Hartley, Hume, Locke, Hobbes, and Francis Bacon, and perhaps it might even count among its remoter ancestors such men as William of Ockham and Roger Bacon. The series of names suggests some permanent congeniality to the national character.(5*) Although, more over, this tradition had in later times been broken by Reid and his followers, their condemnation did not really imply so fundamental an antithesis of thought as Mill supposed. They and the empiricists had, in their own opinion at least, a common ancestor in Bacon, if not in Locke. But, however this may be, the Scottish school had maintained the positions which Mill thought himself concerned to attack; and for him represented the rejection of 'experience.' Experience is a word which requires exposition; but in a general way the aim of the Utilitarians is abundantly clear. They attacked 'intuitions' as Locke had attacked 'innate ideas.' The great error of philosophy, according to them, as according to Locke, has been the attempt to transcend the limits of human intelligence, and so to wander into the regions of mysticism; to seek knowledge by spinning logical structures which, having no base in fact, ended in mere scholastic logomachy; or to override experience by claiming absolute authority for theories which dispense with further proof for the simple reason that no proof of them can be given. To limit speculation and to make it fruitful by forcing it from the first to deal with facts; to trace all its evidence to experience or the observation of facts; and to insist upon its verification by comparison with facts, is the main and surely the legitimate purpose of the Utilitarians as of all their philosophical congeners. The gulf between the world of speculation and the world of fact is the great opprobrium of philosophy. The necessity for finding a basis of fact was emphasised at this time by the rapid development of the sciences which may be called purely empirical, and which had sprung, in any case, from methods of direct observation. This development suggested the elaborate treatise written from a different point of view by Whewell. The great ambition of the Benthamites had been to apply scientific methods to all the problems of legislation, jurisprudence, economics, ethics, and philosophy. Mill could now show, with the involuntary help of Whewell, what those methods really implied The questions remain: What are facts? and, What is experience? and, What are the consequent conditions of reasoning about facts? Admitting that, somehow or other, a vast and rapidly growing body of knowledge has been attained in the physical sciences, we may ask how it has been gained, and proceed to apply the methods in what have been called the moral sciences. Kant's famous problem was, How is a priori synthetic knowledge possible? Mill denies that any such knowledge exists. His problem is therefore, How can knowledge be explained without a priori elements? When this can be satisfactorily done, we shall be able to show how both moral and physical science can be fairly based upon experience. Mill's view of the proper limits of his inquiry is characteristic. He accepts Bacon's account of logic. It, is the ars artium, the science of science itself.'(6*) It implies an investigation into the processes of inference generally. It is not limited to the old formal logic, but includes every operation by which knowledge is extended. It is thus, as he afterwards puts it, the 'theory of proof.'(7*) The book, indeed, owes its interest to the width of the field covered. It has not the repulsive dryness of formal logic, but would lead to a natural history of the whole growth of knowledge, and makes constant reference to the actual development of thought. On the other hand, Mill gives notice that he has no more to do with metaphysics than with any of the special sciences. Logic, he declares, is common ground for all schools of philosophy. It is, he says, the office of metaphysics to decide what are ultimate facts, but for the logician it is needless to go into this analysis.(8*) Accordingly, he often in the course of the book considers himself entitled to hand over various problems to the metaphysicians.(9*) The possibility of really keeping to this distinction is doubtful. Since Mill's very aim is to show that all knowledge comes from observation of 'facts,' it is apparently relevant to inquire what are these 'ultimate facts.' Indeed, his statement, though made in all sincerity, almost suggests a controversial artifice. Logic, as Mill of course admits, affects metaphysics as it affects all sciences; but in one way it affects them very differently. It justifies astronomy, but it apparently makes metaphysics superfluous. Inquiry into the 'ultimate facts' turns out to be either hopeless or meaningless. Mill does not directly assert that all 'ontological' speculations are merely cobwebs of the brain. But he tries to show that, whatever they may be, they are strictly irrelevant in reasoning. All metaphysicians are expected to grant him certain postulates. These once granted, he will be able to account for the whole structure of knowledge. 'Intuitions,' transcendental speculations, and ontology will then be deprived of the whole conditions under which they thrive. I do not now assert, he virtually says, that your doctrine is wrong, but I shall show that it is thrown away. It is a pretence of explaining something which lies altogether beyond the limits of real knowledge, and therefore admits of no explanation. Mill starts from the classification given in old logical textbooks, to which, different as are his conclusions, he attached a very high value.(10*) The schoolmen had by their elaborate acuteness established a whole system of logical distinctions and definitions which are both important and accurate, however sterile the inquiries in which they were used. The machinery was excellent, though its contrivers forgot that a mill cannot grind out flour if you put in no grain. Mill begins accordingly by classifying the various kinds of words in the light afforded by previous logical systems. He is to give a theory of proof. That which is to be proved is a proposition; and a proposition deals with names, and moreover with the names of 'things,' not merely with the names 'of our ideas of things.'(11*) That, in some sense, reasoning has to do with things is of course his essential principle; and the problem consequently arises, What are empirical 'things'?(12*) Though we cannot ask what are 'ultimate things,' the logician must enumerate the various kinds of things to which reference may be made in predication. Mill makes out a classification which he proposes to substitute, provisionally at any rate, for the Aristotelian categories.(13*) The first and simplest class of nameable things corresponds to things 'in the mind,' that is, 'feelings,' or 'states of consciousness,' sensations, emotions, thoughts, and volitions. The second class corresponds to things 'external to the mind'.(14*) and these are either 'substances' or 'attributes.' Here our task is lightened by a welcome discovery. All philosophers, it appears, are now agreed upon one point. Sir W. Hamilton, Cousin, Kant, nay, according to Hamilton -- though that is too good to be true -- nearly all previous philosophers admit one truth.(15*) We know, as they agree, nothing about 'objects' except the sensations which they give us and the order of those sensations. Hence the two 'substances,' body and mind, remain unknowable 'in themselves.' Body is the 'hidden external cause' to which we refer our sensations;(16*) and as body is the 'mysterious something which excites the mind to feel, so mind is the mysterious something which feels and thinks.' The mind is, as he says in language quoted from his father, 'a thread of consciousness,' a series of 'feelings': it is the 'myself' which is conceived as distinct from the feelings but of which I can yet know nothing except that it has the feelings. Thus, although we know nothing of minds and of bodies 'in themselves,' we do know their existence. That is essential to his position. The 'thread of consciousness' is a 'final inexplicability' with him, but it corresponds to some real entity. And, on the other side, we must believe, in some sense, in things. The thing, though known only through the sensations which it excites, must be something more than a mere sensation, for the whole of his logic defends the thesis that in some way or other thought has to conform to facts or to the relations between 'things.' Knowledge, however, is confined entirely to the sensations and the attributes; and the two are at bottom one. The 'verbal' distinction between a property of things and the sensation which we receive from it, is made, he says, for convenience of discourse rather than from any difference in the nature of the thing denoted.(17*) This brings us to a critical point. Attributes, he says, following the old distribution, are of Quality, Quantity, and Relation. Now Quality and Quantity mean simply the sensations excited by bodies. To say that snow is white, or that there is a gallon of water, means simply that certain sensations of colour or size are excited in us by snow or a volume of water. The attribute called 'Relation' introduces a different order of feelings. A 'relation' supposes that two things are involved in some one fact or series of facts.(18*) But it is still an 'attribute' or a 'state of consciousness.' It is a feeling different from other feelings by the circumstance that two 'things' instead of one are involved. This is the explanation which, as we have seen, he praises so warmly in his father's Analysis, and now adopts for his own purposes. It enables him to classify predications. All predication is either an assertion of simple existence or an assertion of 'relations.' By classifying the possible relations, therefore, we obtain the possible forms of predication. It turns out accordingly that we can make five possible predications: we can predicate, first, simple existence; or secondly, 'coexistence'; or thirdly, 'sequence' (these two being equivalent, as he adds, to 'order in place' and 'order in time'); or fourthly, we may predicate 'resemblance'; or fifthly, and this is only to be stated provisionally, we may predicate 'causation.'(19*) So far, Mill's view corresponds to the psychology of the Analysis, which gives a similar account of the various terms employed. J. S. Mill has now the standing ground from which he can explain the whole development of knowledge. At this point, however, he has to diverge from his father's extreme nominalism. Predication, according to the elder, is a process of naming. A predicate is a name of the same thing of which the subject is a name; and to predicate is simply to assert this identity of names. This doctrine, as Mill thinks, is equally implied in the dictum de omni et nullo which is taken as the explanation of the syllogism. We have arbitrarily put a number of things in a class, and to 'reason' is simply to repeat of each what we have said of all. This is to put the cart before the horse, or to assume that the classification precedes the reason for classification, though probably the theory, thus nakedly stated, would not be granted by any one.(20*) What, then, is the true theory? That is explained by the distinction between 'connotation' and 'denotation,' which Mill accepted (though inverting the use of the words) from his father. A general name such as 'man' denotes John, Thomas, and other individuals. It connotes certain 'attributes,' such as rationality and a certain shape. When, therefore, I say that John is a man, I say that he has the attributes 'connoted'; and when I say that all men are mortal, I assert that along with the other attributes of man goes the attribute of mortality.(21*) Predication, then, in general, involves the attribute of 'relation.' We may assert the simple existence of a 'quality,' or, which is the same thing, of a 'sensation'; but to say that John is a man. or that men are mortal, or to make any of the general propositions which constitute knowledge, is to assert some of those 'relations' which are perceived when we consider two or more things together. 'Things,' then, so far as knowable are clusters (in Hartley's language) of 'attributes'; and the attributes may be equally regarded as 'feelings.' To predicate is to refer a thing to one of the clusters, and therefore to assert its possession of the attributes connoted. I will only note in passing that by declining to go into the metaphysical question as to the difference between 'attributes' and 'sensations,' or thoughts and things, Mill leaves an obscurity at the foundation of his philosophy. But leaving this for the present, it is enough to say that we have our five possible types of predication.(22*) All propositions may be reduced to one of the forms. Things exist or coexist or follow or resemble or are cause or effect.(23*) The next problem, therefore, is, How are these propositions to be proved? or, by what tests is our belief to be justified. What may be the nature of belief itself is a question which Mill leaves to the analytical psychologist,(24*) who, as he admits, will probably find it puzzling, if not hopeless. But as we all agree that somehow or other we attain knowledge, we may inquire what is implied in the process. Now, some part of our knowledge obviously depends upon 'experience.' We know of any particular fact from the testimony of our senses. We know that London Bridge exists because we have seen and touched it; and it would be obviously hopeless to try to deduce ts existence from the principle of the excluded middle. London Bridge would then be something independent of time and place. But do we not want something more than bare experience when we lay down a general rule is a law of nature? Then we not only say 'is,' but 'must be'; and this, according to the Intuitionist, marks the introduction of something more than an appeal to 'experience.' There are truths, he says, which represent 'laws of thought'; which are self-evident, or perceived by 'intuition'; or the contrary of which is 'inconceivable.' Without some such laws, we could not bind together the shifting data of experience, or advance from 'is' to 'must be,' or even to 'will be.' We lose all certainty, and fall into the scepticism of Hume, which makes belief a mere 'custom,' regards all things as distinct atoms conjoined but not connected, and holds that 'anything may be the cause of anything.' Mill's aim is to explode the intuitions without falling into the scepticism. Necessary truths, he holds, are mere figments. All knowledge whatever is of the empirical type. 'This has been' justifies 'this will be.' Empirical truths clearly exist, and are held undoubtingly, although they have no foundation except experience. Nobody ever doubted that all men die; yet no 'proof' of the fact could be ever suggested, before physiology was created, except the bare fact that all men have died. If physiology has made the necessity more evident, it has not appreciably strengthened the conviction. We all believe even now that thunder will follow lightning, though nobody has been able to show why it should follow. The ultimate proof in countless cases, if not in all, is simply that some connection has been observed, and, in many such cases, the belief reaches a pitch which excludes all perceptible doubt. As a fact, then, belief of the strongest kind can be generated from simple experience. The burthen of proof is upon those who assume different origins for different classes of truth.(25*) II. SYLLOGISM AND DEFINITION This main thesis leads to two lines of argument. First of all, Mill seeks to show that the methods of proof expounded by his adversaries do not really take us beyond experience; and, secondly, he seeks to show that experience gives us a sufficient basis of knowledge. Let us first notice, then, how the ground is cleared by examining previous accounts of the process of inference. The old theory of reasoning depends upon the syllogism. That gives the type of the whole process by which knowledge is extended. All men are mortal; Socrates is a man, therefore Socrates is mortal. Stewart and Brown had both attacked the syllogism on the familiar ground that it is tautologous. The major has already asserted the minor. To say that one man is mortal when you have already said that all men are mortal, is merely to repeat yourself. There can be no real inference, and no advance to new knowledge. So long as the syllogism is to be explained on the old terms, Mill thinks this criticism fatal; but he holds, too, that by a different interpretation we may assign a real and vitally important meaning to this venerable form of argument. In several places(26*) he gives a view which seems to be much to the purpose. The syllogism, it would seem, corresponds really, not to a mode of reasoning, but to a system of arguing. When a disputant bases some statement upon an inference, we may challenge either the truth of the rule or the statement of fact. The cogency of the argument depends upon the applicability of the rule to the fact. If men be not mortal, or, again, if Socrates be not a man, the inference is not valid; and these two distinct issues, the issue of law and the issue of fact, may be raised in any case.(27*) The value of the syllogism is that it raises these issues distinctly. The argument is thus put in such a form as to be absolutely conclusive if the premises be themselves granted. It therefore provides a test of the validity of the logic. Granting the premises, a denial of the inference must involve a contradiction. That is the only test in pure logic. The syllogism must, therefore, be in a sense tautologous, for otherwise it could not be conclusive. Acceptance o£ the premises must be shown from the form of statement to necessitate the admission of the inference. This follows, and the logical link is complete and irrefragable, if the middle term be identical in both premises, and not otherwise. This is what Mill indicates by saying that 'the rules of the syllogism are rules for compelling a person to be aware of the whole of what he must undertake to defend if he persists in maintaining his conclusion.'(28*) Ratiocination, as he sums up his view elsewhere, 'does not consist of syllogisms'; but the syllogism is a useful formula into which it can 'translate its reasonings,' and so guarantee their correctness.(29*) If this be granted, we must consider the essential step of inference to be embodied in, but not created by, the syllogism. Correct reasoning can always be thrown into this form. The syllogism emerges when the reasoning is complete. 'The use of the syllogism is no other,' says Mill, 'than the use of general propositions in reasoning.' It is a security for correct generalisation.(30*) We have, then, still to ask what is the reasoning process for which the syllogism provides a test. Generalisation implies classification. Our general rule or major premise states some property of a class to which the individual belongs. The question is how this reference to a class enables us to draw inferences which we could not draw from the individual case. To this Mill gives a simple answer, which is already implied in his theory of predication. When I say that Socrates is a man, I say that he has the attributes connoted by the name. He is a rational, featherless biped, for example. But I already know by observation that with these attributes goes the attribute of mortality. The essence of the reasoning process is therefore that, from the possession of certain attributes, I infer the possession of another attribute which has coexisted with them previously. That I do, in fact, reason in this way in countless cases is undeniable. I know that a certain quality, say malleability, goes along with other qualities of colour, shape, and so forth, by which I recognise a substance as gold. I can, it may be, give no other reason for believing the future conjunction of those qualities than the fact of their previous conjunction. The belief, that is, is as a matter of fact generated simply by the previous coincidence or corresponds to constant association. Whether this exhausts the whole logical significance may still be disputed; but, at any rate, upon these terms we can escape from the charge of tautology. The rule in the major premise registers a number of previous experiences of coexistence. When we notice some of the attributes in a given case, we make an addition to our knowledge by applying the rule, that is, by inferring that another attribute may be added to the observed attributes. This, then, gives a rational account of the advance in knowledge made through the syllogism in the case where the class can be defined as a simple sum of attributes. But is this an adequate account of the reasoning process in general? There is another view which suggested difficulties to Mill. His solution of these difficulties, marked, as we learn from the Autobiography, an essential stage in the development of his doctrine. Reference to a class is, upon his interpretation, implied in the syllogism; and classification implies definition. A class means all things which have a certain list of attributes stated in the definition. May we not then infer other properties from the definition? May not mortality, for example, be deducible from the other attributes of man? The assumption that we can do so is connected with the fallacy most characteristic of the misuse of the syllogism. It is plain that we may create as many classes as we please, and make names for combinations of attributes which have no actual, or even no possible, existence. Any inferences which we make on the strength of such classification must be nugatory or simply tautologous. I show that a certain proposition follows from my definition; but that gives no guarantee for its conformity to the realities behind the definition. Your 'proof' that a man is mortal means simply that if he is not mortal you don't call him a man. The syllogism treated on that system becomes simply an elaborate series of devices for begging the question. From such methods arise all the futilities of scholasticism, and the doctrine of essences which, though Locke confuted it,(31*) has 'never ceased to poison philosophy.'(32*) It may, I suppose, be taken for granted that the syllogism was constantly applied to cover such fallacies, and so far Mill is on safe ground. The theory, however, leads him to a characteristic point. Already in the early review (January 1828), he had criticised Whately's account of definition. A 'real definition,' as Whately had said, 'explains and unfolds "the nature" of the thing defined, whereas a "nominal definition" only explains the name.' Whately goes on to point out that the only real definitions in this sense are the mathematical definitions. It is impossible to discover the properties of a thing, a man, or a plant from the definition. If it were possible, we might proceed to 'evolve a camel from the depths of our consciousness,' and nobody now professes to be equal to that feat. When, however, we 'define' a circle or a line and so forth, we make assertions from which we can deduce the whole theory of geometry. A geometrical figure represents a vast complex of truths, mutually implying each other, and all deducible from a few simple definitions. The middle term is not the name of a simple thing, or of a thing which has a certain set of coexisting attributes, but a word expressive of a whole system of reciprocal relations. If one property entitles me to say that a certain figure is a circle, I am virtually declaring that it has innumerable other properties, and I am thus able to make inferences which, although implicitly given, are not perceived till explicitly stated. By assigning a thing to a class, I say in this case that I may make any one of an indefinite number of propositions about it, all mutually implying each other, and requiring the highest faculties for combining and evolving. Pure mathematics give the one great example of a vast body of truths reached by purely deductive processes. They appear to be evolved from certain simple and self-evident truths. Can they, then, be explained as simply empirical? Do we know the properties of a circle as we know the properties of gold, simply by combining records of previous experience? Or can we admit that this great system of truth is all evolved out of 'definitions'? Mill scents in Whately's doctrine a taint of a priori assumption, and accordingly meets it by a direct contradiction. A geometrical definition, he says, is no more a 'real' definition than the definition of a camel. No definition whatever can 'unfold the nature' of a thing. He states this in his review, though it was at a later period,(33*) when meditating upon a passage of Dugald Stewart, that he perceived the full consequences of his own position. In answering Whately, he had said that all definitions were 'nominal.' A 'real definition' means that to the definition proper we add the statement that there is a thing corresponding to the name.(34*) The definition itself is a 'mere identical proposition,' from which we can learn nothing as to facts. But it may be accompanied by a postulate which 'covertly asserts a fact,' and from the fact may follow consequences of any degree of importance. This distinction between the definition and the postulate may be exhibited, as he remarks, by substituting 'means' for 'is.' If we say: a centaur 'means' a being half man and half horse, we give a pure definition. If we say: a man 'is' a featherless biped, our statement includes the definition -- man 'means' featherless biped; but if we said no more, no inference could be made as to facts. If we are really to increase our knowledge by using this definition, we must add the 'covert' assertion that such featherless bipeds exist. The mathematical case is identical, Stewart had argued that geometrical propositions followed, not from the axioms but, from the definitions. From the bare axiom that if equals be added to equals the wholes are equal, you can infer nothing. You must also perceive the particular figures which are compared. Of course the truth of the axioms must be admitted; but they do not specify the first principles from which geometry is evolved. In other words, geometry implies 'intuition,' not the a priori 'intuitions' to which Mill objected, but the direct perception of the spatial relations. We must see the figure as well as admit the self-evident axiom. Mill, on considering this argument, thought that Stewart had stopped at a half truth.(35*) He ought to have got rid of the definitions as well as the axioms. Every demonstration in Euclid, says Mill, might be carried on without them. When we argue from a diagram in which there is a circle, we do not really refer to circles in general, but only to the particular circle before us. If its radii be equal or approximately equal, the conclusions are true. We afterwards extend our reasoning to similar cases; but only one instance is demonstrated. The definition is merely a 'notice to ourselves and others,' stating what assumptions we think ourselves entitled to make; and in this way it resembles the major in the syllogism. The demonstration does not 'depend upon' it, though if we deny it, the demonstration fails. By this argument, Mill conceives that the case of mathematics is put on a level with other cases. We always argue from facts, and moreover from 'particular facts,' not from definitions. We start from an observation of this particular circle -- a sensible 'thing' or object, as in arguing about natural history we start from observation of the camel. Hence we may lay down the general proposition, applicable to geometry as well as to all ordinary observation, that, all inference is from particulars to particulars.'(36*) This is the 'foundation' both of Induction, which is 'popularly said' to reason from particulars to generals, and of Deduction, which is supposed to reason from generals to particulars.(37*) This sums up Mill's characteristic position. III. MATHEMATICAL TRUTHS This attempt to bring all reasoning to the same type forces Mill to ignore what to others seems to be of the essence of the case. There are, he says, two statements: 'There may exist a figure bounded by three straight lines'; that is the fruitful statement of facts. 'This figure is called a triangle'; that is the merely nominal definition or explanation of words. Moreover, as he says, we may drop the definition by substituting the equivalent words or simply looking at the thing. It does not follow that we can dispense with the mode of apprehension implied by the definition. Whether we use the word triangle, or the words, 'three lines enclosing a space,' or no words at all, we must equally have the conceptions or intuitions of lines and space. All demonstration in geometry consists in mentally rearranging a combination of lines and angles so as to show that one figure may be made to coincide absolutely with another figure. The original fact remains unaltered, but the ways of apprehending the fact are innumerable. Newton and his dog Diamond might both see the same circular thing; but to Diamond the circle was a simple round object; to Newton it was also a complex system of related lines, capable of being so regarded as to embody a vast variety of elaborate formulae.(38*) Geometry, as Mill undeniably says, deals with facts. Newton and Diamond have precisely the same fact before them. It remains the same, whether we stop at the simplest stage or proceed to the most complex evolution of geometry. The difference between the observers is not that Newton has seen new facts, but that he sees more in the same fact. The change is not in the things but in the mind, which, by grouping the things in the way pointed out by the definitions, is able to discover countless new relations involved in the same perception. This again may suggest that even the fact revealed to simple perception is not a bare 'fact,' something, as Mill puts it, 'external to the mind,' but is in some sense itself constituted by the faculty of perception. It contains already the germ of the whole intellectual evolution. The change is not in the thing perceived, but in the mode of perceiving. And, therefore, again, we do not acquire new knowledge, as we acquire it in the physical sciences, by observing new facts, discovering resemblances and differences, and generalising from the properties common to all; but by contemplating the same fact. All geometry is in any particular space -- if only we can find it. We do not proceed by comparing a number of different regions of spaces, and inquire whether French triangles have the same properties as English triangles. To Mill, however, the statement that geometry deals with fact leads to another conclusion. We must deal with these facts as with other facts, and follow the method of other natural sciences. We really proceed in the same way whether we are investigating the properties of an ellipse or a camel. In either case we must discover truth by experience. What, then, is really implied in the doctrine that all knowledge rests upon experience? One of Mill's intellectual ancestors lays down the fundamental principle. It is absurd, says Hume,(39*) to try to demonstrate matter of fact by a priori arguments. 'Nothing is demonstrable unless the contrary implies a contradiction. Nothing that is distinctly conceivable implies a contradiction. Whatever we conceive as existent we can also conceive as non-existent. There is no being, therefore, whoa non-existence implies a contradiction.' 'Matter of fact,' then, must be proved by experience; but, given a 'fact' we may deduce necessary consequences. All necessity may be hypothetical; there is an 'if' to every 'must,' but remembering the 'if' the 'must' will be harmless. It can never take us beyond experience. The existence of space itself cannot be called necessary; but space once given, all geometry may 'necessarily' follow, and imply relations running through the whole fabric of scientific knowledge. Mill agrees that a 'hypothetical' necessity of this kind belongs to geometry; and adds, that in any science whatever, we might, by making hypotheses, arrive at an equal necessity.(40*) But then, he goes on to urge, the hypotheses of geometry are not 'absolute truths,' but 'generalisations from observation,' or 'inductions from the evidence of our senses,'(41*) which, therefore, are not necessarily true. This led to his keenest controversies, and, in my opinion, to his least successful answers. He especially claims credit in his Autobiography for having attacked the 'stronghold' of the intuitionists by upsetting belief in the a priori certainty of mathematical aphorisms. In fact, his opponents constantly appealed to the case of mathematics, and Mill assumes that they can be met only by reducing such truths to the case of purely empirical truths. He argues boldly that the 'character of necessity ascribed to the truths of mathematics' is 'an illusion.'(42*) Geometry and arithmetic are both founded upon experience or observation. He goes indeed still further at times. At one place he even holds that the principle of contradiction itself is simply, one of our first and most familiar generalisations from experience.' We know, 'by the simplest observation of our own minds,' that belief and disbelief exclude each other, and that when light is present darkness is absent.(43*) Mill thought himself bound, we see, to refer to experience not only our knowledge of facts, but even the capacities, which are said by another school to be the conditions of perceiving and thus acquiring experience. If he had studied Kant, he might have reached a better version of his own view. As it was, he was led to accepting paradoxes which he was not really concerned to maintain. He had to choose between a theory of 'intuitions' -- so understood as to entitle us to assert matter of fact independently of experience -- and a theory which seems to make even the primary intellectual operations mere statements of empirical fact. Since necessary statements about matters of fact must be impossible, he argues that we cannot even draw necessary inferences from observed fact. Not content with saying that all necessity is hypothetical, he argues that all necessity, even the logical necessity of contradiction, is a figment. If he does not carry out a theory which would seem to make all reasoning unsatisfactory, he maintains, at least, that the hypotheses or assumptions involved in geometry, and even in arithmetic, are generalised from experience, and 'seldom, if ever, exactly true.' If the assumptions are inaccurate or uncertain, the whole superstructure of science must also be uncertain. The nature of his argument follows from his previous positions. He treats space and number as somehow qualities of the 'things,' or as attributes which we observe without in any sense supplying them. His argument upon geometry begins by asserting that there are no such 'real things' as points or lines or circles. Nay, they are not even possible, so far as we can see, consistently with the actual constitution of the universe. It is 'customary' to answer that such lines only exist in our minds, and have therefore nothing to do with outward experience.(44*) This, however, is incorrect psychologically, because our ideas are copies of the realities. A line without breadth is 'inconceivable,' and therefore does not exist even in the mind. Hence we must suppose that geometry deals either with 'non-entities' or with 'natural objects.'(45*) Arithmetic fares little better. When we say that two and one make three, we assert that the same pebbles may, 'by an alteration of place and arrangement' -- that is, by being formed into one parcel or two -- be made to produce either set of sensations.(46*) Each of the numbers, 2, 3, 4, etc., he says elsewhere, 'denotes physical phenomena and connotes a physical property of those phenomena.'(47*) Arithmetic owes its position to the 'fortunate applicability' to it of the 'inductive truth' that the sums of equals 'are equal.'(48*) It is obvious to remark that this is only true of certain applications of arithmetic. When we speak of the numbers of a population, we imply, as Mill admits, no equality except that each person is a unit.(49*) We may speak with equal propriety of a number of syllogisms or of metaphors, in which we have nothing to do with 'equality' or 'physical properties' at all. Further, as he observes,(50*) it is the peculiarity of the case that counting one thing is to count all things. When I see that four pebbles are two pairs of pebbles, I see the same truth for all cases, including, for example, syllogisms. Mill admits, accordingly, that 'in questions of pure number' -- though only in such questions -- the assumptions are 'exactly true,' and apparently holds that we may deduce exactly true conclusions. That ought to have been enough for him. He had really no sufficient reason for depriving us of our arithmetical faith. He can himself point out its harmlessness. As he truly says, 'from laws of spare and number alone nothing can be deduced but laws of spare and number.'(51*) We ran never get outside of the world of experience and observation by applying them. If we count, we do not say that there must be four things, but that wherever there are four things there are also two pairs of things. The unlucky 'pebble' argument illustrates one confusion. 'Two and two are four' is changed into 'two and two make four.' The statement of a constant relation is made into a statement of an event. Two pebbles added to two might produce a fifth, but the original two pairs would still be four. The space-problem suggests greater difficulties. Space, he argues, must either be a property of things or an idea in our minds, and therefore a 'non-entity.' If we consider it, however, to be a form of perception, the disjunction ceases to be valid. The space-perceptions mark the border-line between 'object' and 'subject,' and we cannot place its product in either sphere exclusively. The space-relations are 'subjective,' because they imply perception by the mind, but objective because they imply the action of the mind as mind, and do not vary from one person or 'subject' to another. To say whether they were objective or subjective absolutely we should have to get outside of our minds altogether -- which is an impossible feat. Therefore, again, it is not really to the purpose to allege that such a 'thing' as a straight line or a perfect circle never exists. Whether we say that a curve deviates from or conforms to perfect circularity, we equally admit the existence of a perfect circle. We may be unable to mark it with finger or micrometer, but it is there. If no two lines are exactly equal, that must be because one has more spare than the other. Mill's argument seems to involve the confusion between the statement that things differ in space and the statement, which would be surely nonsense, that the spare itself differs. It is to transfer the difference from the things measured to the measure itself. It is just the peculiarity of space that it can only be measured by space; and that to say one space is greater than another, is simply to say, 'there is more space.' As in the case of number, he is really making an illegitimate transfer from one sphere to another. A straight line is a symmetrical division of space, which must be taken to exist, though we cannot make a perfectly straight line. Our inability does not tend to prove that the 'space' itself is variable. In applying a measure we necessarily assume its constancy; and it is difficult even to understand what 'variability' means, unless it is variability in reference to some assumed standard. If, as Mill seems to think, space is a property of things, varying like other properties, we have to ask, In what, then, does it vary? All other properties vary in respect of their space-relations; but, if space itself be variable, we seem to be reduced to hopeless incoherence. Thus, to ascribe necessity to geometry as well as to arithmetic is not to ascribe 'necessity' to propositions (to use Hume's language again) about 'matters of fact.' The 'necessity' is implied in a peculiarity which Mill himself puts very forcibly,(52*) and which seems to be all that is wanted. An arithmetical formula of the simplest or most complex kind is an assertion that two ways of considering a fact are identical. When I say that two and two make four, or lay down some algebraical formula, such as Taylor's theorem, I am asserting the precise equivalence of two processes. I do not even say that two and two must make four, but that, if they make four, they cannot also or ever make five. The number is the same in whatever order we count, so long as we count all the units, and count them correctly. So much is implied in Mill's observation that counting one set of things is counting all things. The concrete circumstances make no difference. The same is true of geometry. The complex figure may be also regarded as a combination of simpler figures. It remains precisely the same, though we perceive that besides being one figure it is also a combination of figures. This runs through all mathematical truths, and, I think, indicates Mill's precise difficulty. He says quite truly that to know the existence of a fact you must always have something given by observation or experience. The most complex mathematical formulae may still be regarded as equating different statements of the same experience. The difference is only that the experience is evolved into more complex forms, not by any change in the data supplied, but by an intellectual operation which consists essentially in organising the data in various ways. The reasoner does not for an instant desert fact; he only perceives that it may be contemplated in different ways, and that very different statements assert the very same fact or facts. Our experience may be increased, either by the entrance of new objects into our field of observation, or by the different methods of contemplation. The mathematician deals with propositions which remain equally true if we suppose no change whatever to take place in the world, or, as Mill puts it, 'if all the objects of the universe were unchangeably fixed.'(53*) His theories, in short, construct a map on which he can afterwards lay down the changes which involve time. The filling up of the map depends entirely upon observation and experience; but to make the map itself a mere bundle of accidental coexistences is to destroy the conditions of experience. The map is our own faculty of perception. 'There is something which seems to require explanation,' says Mill,(54*) 'in the fact that an immense multitude of mathematical truths... can be elicited from so small a number of elementary laws.' It is puzzling when you identify Newton with Diamond on the ground that they both see the same 'fact.' But it is no more puzzling than anything else, as indeed Mill proceeds to show, when we observe the method by which in arithmetic, for example, an indefinite number of relations is implied by the simple process of counting. The fact is the same for all observers, in so far as they have the same data; but to perceive the data already implies the germ of thought from which all the demonstrative sciences are evolved. The knowledge can be transformed and complicated to an indefinite degree by simply identifying different ways of combining the data. Mill, in his anxiety to adhere to facts and experience, fails to recognise adequately the process by which simple observation is evolved into countless modifications. The difficulty appears in its extreme form in the curious suggestion that even the principle of contradiction is a product of experience. Mill is so resolved to leave nothing for the mind to do, that he supposes a primitive mind which is not even able to distinguish 'is not' from 'is.' It is hard to understand how such a 'mind,' if it were a 'mind,' could ever acquire any 'experience' at all. So when Mill says that the burthen of proof rests with the intuitionist, he is, no doubt, quite right in throwing the burthen of proof upon thinkers who suppose particular doctrines to have been somehow inserted into the fabric of knowledge without any relation to other truths; but it is surely not a gratuitous assumption that the mind which combines experience must have some kind of properties as well as the things combined. If it knows no 'truths' except from experience, it is at least possible that it may in some way react upon the given experience. This, at any rate, should be Mill's view, who takes 'mind' and 'body' to be unknowable, and all knowledge of fact to be a combination of 'sensations.' He only requires to admit that knowledge may be increased either by varying the data or by varying the mind's action upon fixed data. In neither case do we get beyond 'experience.' In many places, Mill seems to interpret his view in consistency with this doctrine. His invariable candour leads him to make admissions, some of which I have noticed. Yet his prepossessions lead him to the superfluous paradoxes which, for the rest, he maintains with remarkable vigour and ingenuity. One other device of the enemy raised the troublesome question of inconceivability as a test of truth, which brought Mill into conflict not only with Whewell and Hamilton, but with Mr Herbert Spencer. I will only notice the curious illustration which it affords of Mill's tendency to confound statements of fact with the purely logical assertion that two modes of stating a fact are precisely equivalent. The existence of Antipodeans, in his favourite illustration,(55*) was declared to be 'inconceivable.' Disbelief in their existence involved the statement of fact: gravity acts here and at the Antipodes in the same direction. That statement could of course be disproved by evidence; and there is no reason to suppose that the truth, once suggested, would be less 'conceivable' to Augustine or, say, to Archimedes, than to Newton. It also involved the assertion: men (if the direction of gravity were constant) would drop off the earth at the Antipodes as they here drop off the ceiling. The denial of that statement is still 'inconceivable,' though the statement ceases to be applicable. Mill, however, infers that, as an 'inconceivability' has been surmounted, 'inconceivability' in general is no test of truth. 'There is,' he says,(56*) 'no proposition of which it can be asserted that every human mind must eternally and irrevocably believe it,' and he tries, as I have said, to apply this even to the principle of contradiction. In other words, because our logic requires a basis in fact, and the fact must be given by experience, the logic is itself dependent upon experience. If 'inconceivable' be limited, as I think it should be limited in logic, to the contradictory, an inconceivable proposition is incredible because it is really no proposition at all. We may, no doubt, believe statements which are implicitly contradictory. but when the contradiction is made explicit, the belief becomes impossible. Similarly we may disbelieve statements which appear to be contradictory; and when the error is exposed, we may believe what was once 'inconceivable.' That only shows that our thoughts are often in a great muddle, and in great need of logical unification. It does not prove any incoherence in the logical process itself. IV. CAUSATION We can now proceed to what may be called the constructive part of the logic. We have got rid of proofs from intuitions, from definitions, and from inconceivabilities, and the question remains how we can prove anything. All knowledge is inductive. It is all derived from facts; it proceeds from particulars to particulars; the previous coexistence of sequences which have been observed constitute our whole raw material. What, then, serves to bind facts together? or how are we to know that facts are bound together, or that any two given facts have this relation? The fundamental postulate of science is the so-called 'uniformity of nature.' But Nature, as it is seen by the unscientific mind, is anything but uniform. There are, it is true, certain simple uniformities which frequently recur. Fire burns, water drowns, stones thrown up fall down; and such observations are the germs of what we afterwards call scientific 'laws.' But things are constantly happening of which we can give no account. Catastrophes occur without any assignable 'antecedent'; storm and sunshine seem to come at random; and the same combination of events never recurs in all its details. Variety is as manifest as uniformity. How can cosmos be made out of chaos? How do we come to trace regularity in this bewildering world of irregularities? From any fact taken by itself, as Hume had fully shown, we can deduce no necessity for any other fact. The question is, whether we are to account for the belief in uniformity by an 'intuition' or by James Mill's universal solvent of 'association of ideas.' J. S. Mill was fully convinced of the efficacy of this panacea, but he sees difficulties over which his father had passed. If association explains everything, the tie between ideas ought to be stronger, it might be supposed, in proportion to the frequency of their association. The oftener two facts have been joined, the more confidently we should expect a junction hereafter. But this does not hold true universally. A chemist, as Mill observes, analyses a substance; and assuming the accuracy of his results, we at once infer a general law of nature from 'a single instance.' But if any one from the beginning of the world has seen that crows are black, and a single credible witness says that he has seen a grey crow, we abandon at once a conjunction which seemed to rest upon invariable and superabundant evidence. Why is a 'single instance' sufficient in one case, and any number of instances insufficient in the other? 'Whoever can answer this question,' says Mill, 'knows more of the philosophy of logic than the wisest of the ancients, and has solved the problem of induction.'(57*) Here Mill again professes to set metaphysics aside. He has nothing to do with 'ontology.' He deals with 'physical,' not 'efficient,' causes. He does not ask whether there be or be not a 'mysterious' tie lying behind the phenomena and actually producing them.(58*) He is content to lay down as his statement of the 'law of causation' that there is an invariable succession between 'every fact in nature' and 'some other fact which has preceded it.' This, he assumes, is a truth, whatever be the nature of things in themselves. The true account is rather that he will show that 'ontology' is a set of meaningless phrases. He can answer his problem without it. Causation is, in fact, conceived by him as it was conceived by all the psychologists, including Brown; and he has simply to show that Brown's supposed 'intuition' is a superfluity. His treatment of the question gives the really critical part of his philosophy. It leads to some of the results which have been most highly and, as I think, most deservedly praised. It also leads to some of his greatest errors, and shows the weak point of his method. Mathematical knowledge, as Mill remarks, has nothing to do with causation. Every geometrical or arithmetical formula is true without supposing change. One theorem does not 'cause' the others; it 'implies' them. The most complex and the most simple are mutually involved in the single perception, though our knowledge of one may be the cause of our knowing the others. Their necessity is another way of stating this implication. We can show that to deny one theorem while admitting another is to be contradictory. The whole of physical science, however, from first to last, is a process of stating the changes of phenomena in terms of time and place, and therefore brings them all within the range of mathematical methods. Science is not fully constituted till it becomes quantitative or can speak in terms of definite relations of magnitudes. How, then, are its laws necessary? It is contradictory to say that the same thing has different space-relations at the same time; but there is no contradiction in saying that it is here now and somewhere else to-morrow. The formula of the 'uniformity of nature,' whatever may be its warrant, transfers the necessity of the geometrical theorem to the laws of phenomena. We assume that things are continuous or retain identity in change. We are no more permitted to say that the combination of the same elements may produce a compound of different properties, than to say that the product of two numbers may sometimes give one result and sometimes another. Every change is regarded as regular, or as having a 'sufficient reason.' The same series of changes therefore must take place under the same conditions, or every difference implies a difference in the conditions. So far as we carry out this assumption, we resolve the shifting and apparently irregular panorama into a system of uniform laws. Each law may be, and if it be really a law must be, absolutely true, not in the sense that it states a fact unconditionally, but that it is stated so that the conditions under. which it is absolutely true are fully specified. If we could reach a complete science of all physical phenomena, we should have a system of connected laws as infallible and mutually consistent as those of geometry or arithmetic. But in order thus to organise our knowledge, we have to alter -- not the facts -- but the order of grouping and conceiving them. We have to see identities where there were apparent differences, and differences in apparent identities, and to regard the whole order of nature from a fresh point of view. The fact remains just as it was; but the laws -- that is, the formulae which express them -- are grouped upon a new system. The questions remain, What is the precise nature of the scientific view? and What is our guarantee for a postulate which it everywhere implies? The chapter upon causation(59*) is a vigorous assertion of Mill's position. He accepts the traditional view of his school, that cause means invariable sequence; but he makes two very important amendments to the previous statements. A simple sequence of two events is not a sufficient indication, however often repeated, that they are cause and effect. We speak, he says, of a particular dish 'causing' death; but to be accurate we must also include, as part of the cause, all the other phenomena present, the man as well as the food, the man's state of health at the time, and possibly even the state of the atmosphere or the planet. The real cause must include all the relevant phenomena. The cause, therefore, is, 'philosophically speaking,' the 'sum total of the conditions,' positive and negative, 'taken together, the whole of the contingencies of every description, which, being realised, the consequent invariably follows.'(60*) Mill's second amendment is made by saying that the cause does not signify simply 'invariable antecedence,' but also 'unconditional' sequence. There may be 'invariable' sequences, such as day and night -- a case often alleged by Reid and others, which are not 'unconditional.' The sun, for anything we can say, might not rise, and then day would not follow night. The real condition, therefore, is the presence of a luminous body without the interposition of an opaque screen.(61*) These are undoubtedly material improvements upon previous statements; and this view being admitted, it follows, as Mill says, that the state of the whole universe is the consequence of its state at the previous instant. Knowing all the facts and all the laws at any time we could predict all the future history of the universe.(62*) Some curious confusions, it must be noticed, result apparently from Mill's use of popular language. The most singular is implied in his discussion of the question whether cause and effect can ever be simultaneous. Some 'causes,' he says, leave permanent effects; a sword runs a man through, but it need not remain in his body in order that he may 'continue dead.'(63*) The 'cause' here is taken to mean the 'thing' which was once a part of a set of things, and has clearly ceased to mean the sum of all the conditions. 'Most things,' he continues, once produced, remain as they are till something changes them. Other things require the continual presence of the agencies which produced them. But since all change, according to him, supposes a cause, it is clear that not only 'most things' but all things must remain as they are till something changes them. Persistence is implied in causation as much as change, for it is merely the other side of the same principle. Inertia is as much assumed in mechanics as mobility; for it is the same thing to say that a body remains in one place when there is no moving force, as to say that whenever it ceases to remain there is a moving force. The difference which Mill means to point out is that some changes alter permanent conditions of other changes, as when a man cuts his throat and all vital processes cease; while sometimes the change leaves permanent conditions unaffected, as when a man shaves himself, and his vital processes continue. But in no case is the effect produced, as he says, after the cause has ceased; it is always produced through the actually present conditions, which may have come into their present state through a change at some more or less remote period. Each link in a chain, according to the common metaphor, depends upon all the previous links and may be said to hang from them; but the distant link can only act through the intermediate links. These slips imply a vagueness which leads to more serious results. Mill's aim is to construct a kind of logical machinery -- a sieve, if I may say so, through which we pass all the phenomenal of the universe in order to find out which are really loose and which are connected by the ties of causation. We are unweaving the complex web of nature by discovering what is the hidden system of connections in virtue of which one event or thing is somehow fastened to another. Everything, we may say, which appears is called up by something else -- the thunder by the lightning, the death by the poison, and so forth. In every case we can reduce a statement of causation to the form of an assertion of sequence or coexistence. Here, as he observes, we meet one difficulty. Everything is connected with some other thing. But then it may or must be also connected with a third. The two connections may interfere, and we have to consider how they can be disentangled. This leads to a distinction to which he attaches, very rightly, I think, the highest importance. In some cases, the correct version of the facts can be obtained by simply superposing the laws of simpler cases. A body moves to the north under certain conditions; but other conditions force it to move also east or south. We then have only to combine the two 'laws,' and to say that it is moving both north and east, that is, north-east, or perhaps to interpret rest as an equal movement to both north and south. This, as he remarks, represents the general case in regard to mechanical phenomena. We have simply to combine two rules to get what is called in dynamics 'the composition of forces'; and, in accordance with this phase, he uses the general phrase, 'the composition of causes.'(64*) But, as he observes, this principle is in many cases not applicable. In chemical combinations, in particular, we cannot infer the properties of the compound from the properties of the components. The laws of simple substances will not give us the laws of the product, and we can only learn these derivative laws by experiment. This holds, still more conspicuously, of organised bodies. From considering the properties of its chemical constituents separately you cannot deduce the properties of the human body. We thus come to a kind of knot in the web; we are at a deadlock, because the laws from which we start are superseded by an entirely different set of laws. Mill marks this by speaking of 'heteropathic laws.'(65*) Such laws are not analysable into simple laws. He thinks, indeed, that 'heteropathic laws' are -- at least 'in some cases may be derived from the separate laws, according to a fixed principle.' The fact to which he calls attention is undeniable. We discover countless laws as to the properties of bodies which it is impossible at present either to resolve into simpler laws, or to deduce from the laws of the constituent elements. Such laws are properly 'empirical.' The observation of the facts asserted is the sole guarantee for our belief in their truth; and they can he reduced under no more general formula. Is this, however, simply a challenge to the man of science to inquire further, or does it oppose an insuperable obstacle to further scientific researches? Mill avowedly limits himself to 'our present state of knowledge.' He recognised that Grove, in his Correlation of Forces,(66*) made out a strong, though still only a probable, case for believing that a 'heteropathic law' may represent a complete transformation of one set of forces into another. Heat, light, and magnetism may be all different manifestations of a single force -- not so much causes of one another as 'convertible into one another.'(67*) Grove, as Mill adds, is not, as might be supposed, deviating into ontology, but giving a strictly philosophical statement. Mill is here speaking of a great principle, imperfectly known at the time, which has been accepted by modern science, and he is quite ready to welcome it. It is, however, noticeable that he still guards himself against admitting any intrusion of 'necessity.' He will not allow that the dependence of the properties of compounds upon these elements must result in all cases 'according to a fixed principle.' The meaning of this may appear from his later assault upon the doctrine that 'like produces like.' This he reckons among the fallacies which he discovers in all manner of pestilent a priori philosophising. Descartes, Spinoza, Leibniz, and Coleridge have all been guilty of it in various forms.(68*) We are therefore under no obligation to go further when we come to totally disparate phenomena in our series. We have unravelled our web sufficiently when we find laws disappearing and being superseded by a totally different set of laws, not describable even in the same language. That we may be forced to be content with such a result is undeniable. But it is equally true that one main end of scientific theorists is to get round this difficulty. Without inquiring in what sense the axiom that 'like produces like' may be fallacious, we must at least admit that to give a scientific law -- that is, a rule by which one set of events is deducible from another -- we must be able to express it in terms of some single measure. Til I we can get such a statement, we have not the complete formula. There is a breach of continuity in our theories, which we try to remove by reducing all the forces to measures assignable in terms of space and number. The hypothesis of an ether and vibrating atoms enables us to regard phenomena as corresponding in some way to the laws which, as Mill says, can be compounded by simple superposition, without introducing heterogeneous terms. Though he does not condemn this hypothesis, Mill regards it with a certain suspicion as an attempt to wander into ontology, and the search for what is in its nature inaccessible.(69*) At any rate, it does not appear to him that further inquiry is necessary when we come to an irreducible breach of continuity. to a case in which one set of phenomena is simply superseded by another, instead of being transformable into it. If a compound is made of certain elements exclusively, a physicist would clearly infer that its properties must be a result of the properties of the elements according to 'some fixed principle.' Mill is only prepared to admit that this may be the case. The physicist, again, seeks for a mode of stating the principle in theorems capable of being combined and superposed, whereas Mill holds that our knowledge may have come to an ultimate insuperable end. V. PLURALITY OF CAUSES It is in the applications of this view that we come to what must be regarded as downright fallacies. If, as Mill holds, an effect may be something absolutely disparate from the cause -- a new thing which starts into existence when its antecedent occurs -- we are led to another result. There is, then, no apparent reason why the same thing should not spring up in answer to different summonses. Not only is this possible, but, as Mill thinks, it constantly occurs. This is his doctrine of the 'Plurality of Causes.' A given cause, he holds, can only produce one effect. But a given effect may follow various causes. So long as the relation is merely one of arbitrary succession, not of continuity, this is obviously possible. The fully scientific view, I take it, would be that when we speak of 'cause and effect' we are really thinking of a single process regarded in different ways. We may analyse the process differently for different purposes, and infer the past from the future or the future from the past; but we assume that, if we could perfectly understand the whole process, there would be thorough continuity, and no abrupt supersession of one thing or one set of 'laws' by another. This continuity is precisely what Mill systematically denies. A cause, he holds, means an absolute beginning of a new effect.(70*) The process becomes a series of distinct terms -- a set of 'links' in a chain, not a flow of a stream. One remarkable case is enough to illustrate the point. When Bacon's claims to have founded a truly scientific theory are considered, it is generally said that his guess as to the nature of heat is a point in his favour.(71*) Mill, however, takes this particular case as an instance of Bacon's errors. Bacon, he says,(72*) 'entirely overlooked the Plurality of Causes. All his rules imply the assumption, so contrary to what we now know of nature, that a phenomenon cannot have more than one cause.' Bacon was misguided enough to apply this to heat. Now, as Mill had already argued, heat may have several causes: the 'sun,' or 'friction,' or 'percussion,' or 'electricity,' or 'chemical action.'(73*) Consequently, the attempt to find a single cause is doomed to failure. We shall find, not that one antecedent but, that one of several antecedents is always present. Clearly the 'sun' is not 'friction,' nor is 'percussion' 'electricity.' Each of those phrases indicates concrete facts involving various processes. Heat, as a 'mode of motion,' occurs in them all, because all involve particular phases of movement. From the 'raw' fact, as it presents itself -- 'This body is hot' -- I cannot say which of various laws represents the true antecedents in that case. The heat may have been caused by exposure to fire or by friction. In that sense, undoubtedly, one effect may really have any number of 'causes.' But replace all the conditions, and it is evident that there can be only one true analysis of the whole process. Mill's insistence upon this imaginary 'plurality of causes' is significant. It indicates the precise stage in the development of the idea of cause to which his doctrine corresponds. Taking what we may call the popular sense of causation, the 'plurality' expresses an obvious truth; and we can understand its plausibility. We take, in fact, two concrete events which follow each other, and call them cause and effect. We use a tool -- a knife to cut bread, for example; we are forced to attend to the fact that every difference in the knife will have an effect on the result. The work is better or worse, as the knife is sharper or blunter. If we did not recognise this in every purposeful action, all action would be intrinsically uncertain. We are, therefore, impressed with the necessity of admitting that the effect is determined by the cause. But, on the other hand, the knife is there. It may have been made by fifty different methods, and yet be the same. The handle may have been first made and then the blade, or vice versa, and so forth. therefore we believe, and in this sense of cause believe correctly, that one effect may be the product of any number of different 'causes.' In order to reach the more scientific sense of causation, we have to take into account all that we have neglected. The knife is one product of an indefinite multitude of processes, and is therefore not the total 'effect' of the concrete antecedent, but only a part of it arbitrarily singled out. We do not attend to all these collateral results, because for us at the moment they have no interest; but when we systematically carry out the 'uniformity of nature' principle, it is obvious that they must be taken into account. We then see that although precisely similar products appear in an infinite variety of concrete processes, they correspond only to a part of those processes, and may always be analysed into identical elements. The effect can no more have two causes than a cause two effects, for cause and effect are distinguished by observing the same process in a different order. It was just because men of science held that the one effect must have one cause that they could make a coherent theory of heat. Mill, however goes a step further. Bacon's error was the assumption that there was only one 'form' of heat. Now it is specially futile, says Mill, to seek for the causes of 'sensible qualities of objects.... In regard to scarcely any of them has it been found possible to trace any unity of cause.' Bacon, therefore, was seeking for 'what did not exist,' and to this Mill adds the surprising statement that 'the phenomenon of which he sought for the one cause has oftenest no cause at all, and, when it has, depends (as far as hitherto ascertained) on an unassignable variety of causes.'(74*) To explain this rather startling assertion we must take one more of Mill's theories. How from the doctrine, which he fully admits, that every event has a cause can he reach the conclusion that some things have 'no cause at all'? Once more we have, I think, the misapplication of an undeniable truth. A 'law' of causation, taken by itself, will obviously not fully account for a single fact. It cannot lead to the conclusion: 'this fact must exist,' but only to the conclusion: this fact must exist if certain previous facts existed. We somewhere assume an initial stage. However far back we can go, we may still repeat the question. Given a single state of facts and the 'laws of causation,' we can go indefinitely backwards or forwards in time. Given the sun, the planets, and gravitation, we can trace the whole past and future history of the solar system; but the facts at some period must be 'given.' We cannot say that they must, but only that they do exist. Mill himself puts this(75*) with all desirable clearness. He expresses it by saying that besides 'causation' there is 'collocation,' a word, he says, suggested by Chalmers.(76*) To know the 'collocation,' therefore, is essential. A 'law' does not tell us that there 'must' be plums and suet, but only that if there are such things in certain 'collocations' a plum pudding 'must' be the result. All statements of fact have thus an empirical basis. This, however, takes a peculiar turn in his exposition, and one which is characteristic of a Utilitarian failing. He makes the distinction of relations correspond to a distinction of things. Instead of saying that both causation and collocation are implied in all phenomena, he speaks of some 'uniformities' as dependent upon causation and others as dependent upon collocation. He therefore writes a chapter on 'uniformities of coexistence not dependent on causation.'(77*) This, however, is closely connected with, and must be explained by, another doctrine to which he attached the highest importance. After telling us how he was started afresh by Stewart's account of axioms, he adds that he came to 'inextricable difficulties' in regard to induction. He had come to the 'end of his tether,' and 'could make nothing satisfactory of the subject.' When, after five years' halt, he again set to work, he introduced his 'theory of kinds,' which, as he intimates, got round the difficulty. He felt, as we may conjecture, that he had now reduced all the facts to such purely empirical conjunctions that he did not see how to get any tie between them. Any cause, so far as we have gone, might lead to any effect. and even when we have seen a case of conjunction, we can give no reason for its recurrence. Induction enables us to predicate attributes of a class; but a logical class is itself merely a bundle of attributes arbitrarily selected, and it remains to see why, from a thing's possession of some of the class attributes, we can infer that it has the others. Why should not the same set of attributes form part of different bundles? and if so, what is the justification for the primary logical procedure? From featherless bipedism we infer mortality. But why may not some class of featherless bipeds be immortal? If we admit the possibility, all induction becomes precarious. The 'theory of kinds' was, it seems, intended as an answer to these obvious difficulties. VI. REAL KINDS Mill's account of 'real kinds' corresponds, as he tells us, to the old logicians' distinction between genus and species. Though our classification may be arbitrary and nothing properly deducible from it, except the mere fact that we have chosen to give names to certain clusters of attributes, there is also a real difference. Some of our classes do not correspond to 'real kinds,' and are mistaken for them. Others, however, correspond to a real or natural kind. The difference is this: a 'real kind' has an 'indeterminate multitude of properties, not derivable from each other,' whereas an arbitrary or merely logical 'kind' may only differ in respect of the particular attribute assigned. Thus, to say that Newton is a man is to attribute to him the 'unknown multitude of properties' connoted by 'man.' To say that Newton is a Christian is only to attribute to him a particular belief and whatever consequences may follow from having that belief.(78*) One classification, as he says, 'answers to a much more radical distinction in the things themselves, than the other does'; and a man may thus fairly say, if he chooses, that one classification is made 'by Nature' and one 'by ourselves,' provided that he means no more than to express the distinction just drawn. Now, it is easy to understand why Mill felt that this assertion entitled him to a 'real' bond which would keep phenomena together in a more satisfactory way. All things had become so loose and disconnected that it was difficult to explain any extension of knowledge even by induction. Yet, whatever the reason, things do stick together in coherent and many-propertied clusters. The bond seems to be real when it is stated 'objectively,' not 'subjectively' -- as a property of the things observed, not of the classes made by the mind itself. I take the remark to be both true and important; and, moreover, that Mill deserves credit for perceiving so clearly this weak joint in his armour. His application, however, suggests, when he had hit upon an apparent escape from his 'inextricable' difficulties, he was too much relieved to work out its full effect upon his general theory. The 'theory of kinds' is inserted rather than embodied in his philosophy, and makes rents in the attempt to fill a gap. It plays, however, so important a part in the doctrine that it requires some further consideration. A real kind, we see, has two characteristics; it has innumerable properties, and those properties are not 'derivable' from the others. In fact, a derivative property would be merely a modification of a primitive property. A geometrical 'kind,' a curve of the second order, for example, has innumerable properties, but they are all derivative from the simple properties expressed in the axioms and definitions. They reciprocally imply each other. But can we say the same of the properties of a thing -- of a plant or of water or of an atom? Here we have the distinction already noticed. The so-called 'thing' may be merely a collection of separate things, and we can discover the 'laws' applicable to all by combining the laws applicable to each. From a given 'collocation' we can infer past or future 'collocations,' and one set of results can be added to or superposed upon the other. But when we proceed to chemical or organic compounds, we have 'heteropathic' laws. The compound may be analysed into elements, but we cannot derive the properties of the compounds from the properties of the elements. Hydrogen and oxygen can be combined into the form of water; but we could not infer the properties of water from the properties of the hydrogen and oxygen taken apart. In organic compounds, the problem is still more intricate. We have to consider a series of inter-related changes taking place within the organism, and dependent partly upon the 'environment' and partly upon the complex constitution of the organism itself. It is a unit in so far as all its properties manifest an organic law or a system of organic laws. Individuals may differ from external causes as plants, for example, in different soils, and in that case we may regard the differences as simply derivative. Differences which belong to the organic law itself indicate differences of kind; and these are ultimate for us, so long as we cannot trace the way in which they are dependent upon differences of constitution. These, roughly stated, are the facts which Mill recognises. Now, in any case whatever, we can only 'explain' a fact by assuming both 'collocation' and 'causation'; or, in other words, we must have a statement of facts and of laws. Our analysis of the phenomena will in all cases come to showing how a given state results from, or results in, a previous or succeeding state. If new properties appear from the combination of simpler elements, we should infer that they result, though we may be quite unable in the existing state of knowledge to show how they result, from the properties of those elements. The properties do not manifest themselves, and are therefore not discoverable, till the combination is formed; and are thus only known to us 'empirically.' No process of reasoning, that is, can be adduced to show that they must result from the combination. But, in the case supposed, we do not doubt that they do result, and we assume that the elements had certain latent properties not previously discoverable. This, however, is the point upon which Mill diverges, owing, as I think, to his imperfect view of causation. The doctrine of 'kinds,' in fact, gives the answer to Mill's old problem, why a single instance is sometimes conclusive, whereas any number of instances may sometimes fail to give certainty. It is this reciprocal connection between the properties of a 'kind' which justifies the inference from one set of attributes to another attribute -- the inference implied in all induction. But Mill's interpretation of the fact seems strangely inconsistent. His favourite instance is the black crow. I have seen a million black crows. Can I say that the million and oneth crow will be black? To answer this we must ask whether blackness is a property of 'kind.'(79*) If the blackness be, 'as it were, an accident,' or not a property of kind, it must, he says, be a case of causation. If not a case of causation, it must be a property of kind. Hence we have the singular result, that if the coexistence be casual, it is caused, and if invariable, not caused. As 'causation' means according to him simply unconditional connection, the statement seems to be especially paradoxical. It is, however, explicable. The blackness of the crow may be regarded as 'accidental,' if it is due to the external cause. The crow, perhaps, has fallen into a paint-pot. The blackness is 'caused,' then, by the properties of paint and by the 'accidental' collocation. It is an 'accident' in the crow, though caused in respect of the general arrangements of the universe. But why, if a property of 'kind,' should it be called 'not caused'? Here we have a curious result of Mill's view of causation. Our natural reply would be that the colour is still caused as everything else is caused.(80*) We assume, that is, that 'crow' implies such a constitution that under a given environment crows will be black. Change something outside the crow and he may turn white. Or find a white crow in the same 'environment,' and we infer some difference in his constitution. There is a relation, we assume, though we cannot specify its nature, which determines the colour, and as in all cases we have at once collocation and causation. Here is Mill's peculiar difficulty. Causation, as he is profoundly convinced, always means a beginning. It is only, as we have seen, concerned with changes, not with persistence. Therefore, if two things, like blackness and crowness, exist side by side, it is a case of collocation, and consequently, as he supposes, not a case of causation. He cannot recognise a reciprocal relation, although it is clear that if one thing is found always to accompany another, the argument is the same as though one always followed another. Indeed, his whole theory of induction implies the possibility of reasoning from one property or attribute to another. Make a change in one and the other must be changed. He sees this clearly in the case of organised bodies.(81*) In that case, he says, there is a 'presumption' that the properties are 'derivable' and therefore 'caused,' because there we have sequences or one process following another. He thus seems to limit his 'natural kinds' chiefly to chemical compounds. There we have properties lying side by side and not 'derivable,' that is, not to be inferred by us from the properties of the elementary constituents. The very attempt to derive them is idle. As any event may cause any other, however unlike, so any set of properties may be simply stuck together. Bacon is again reproved(82*) for assuming that 'every object has an invariable coexistent.' The ultimate properties, so far as we can conjecture, are 'inherently properties of many different kinds of things, not allied in any other respect.' They simply lie side by side, without reference to each other. Thus Mill pushes his empiricism to assuming not only that our knowledge of properties must rest upon direct observation, but that there is absolutely no connection or 'cause' to be known. The 'kind' after all, which was meant to be an essential bond, turns out to be itself a purely arbitrary collection of attributes, and we have to ask whether it does not lose all the significance which he attached to it. The 'collocation' means that the attributes simply lie side by side, and yet are always conjoined. The tie which combines them is undiscoverable, and therefore for us non-existent. It is, as he rightly insists, important that our classification should correspond to natural kinds. 'Kinds,' he says, are classes 'between which there is an impassable barrier'; the logical class is arbitrary, but the real class is an essential fact, His illustration is remarkable. He holds that the 'species of plants are not only real kinds, but are probably all of them real lowest kinds, infimae species,' and that further subdivision would lead to no valuable results.(83*) The doctrine that the species of botany must correspond to 'real kinds ' is curious in a writer who was himself a botanist and familiar with the difficulty of making absolute divisions between kinds. The conflict with the conceptions implied in Darwinism is of the highest importance.(84*) The distinction between 'kinds,' according to Darwin, is not absolute, for it is the product of gradual divergence from a single form. But, on the other hand, the kinds existing at a given time are discrete. There are gaps between them, as Mill remarks; though, in so far as they have a common origin, not absolutely insuperable gaps. This implies that the organism does not correspond to a mere aggregate of disconnected attributes, so that the difference of kinds would be simply a difference of more or less, and each type pass into the other by imperceptible gradations. We are obliged to suppose a system of reciprocal relations, so that any change in one organ involves correlated changes in others; and thus species diverge along different lines instead of remaining constant or simply adding on new properties. Mill, it seems, has to admit of kinds in order to account for the possibility of inference; but then, as he wishes to avoid 'mystical bonds,' and inferences from 'definitions,' and the scholastic beggings of the question, he declares the relation between the attributes to be 'accidental' or 'uncaused.' Hence, though he sees the difficulty and recognises the probability of 'causation' in organised bodies, he really reduces the 'kind' to be a mere aggregate, and destroys the very organic bond of which he is in need. VII. UNIFORMITY OF NATURE The effect of thus contra-distinguishing 'collocation' from causation, and admitting that 'uncaused coexistences' cover a large part of all observable phenomena, is to make the uniformity of nature exceedingly precarious. Indeed, Mill denies it to be conclusively proved. The chapter in which he sums up 'the evidence of the law of universal causation' leads to remarkable results. No one, he thinks, with a properly trained imagination will find any difficulty in conceiving that in remote parts of the universe 'events may succeed one another at random without any fixed law'. He concludes by asserting that it would be 'folly to affirm confidently' that the law does prevail in 'distant parts of the stellar regions.'(85*) A truth which depends upon locality might, for anything one sees, break down in Australia and even at Paris as easily as at Sirius. Mill, accordingly, reaches a thoroughly sceptical conclusion,(86*) and reduces the evidence for universal causation to an induction per enumerationem simplicem. The wider the generalisation, the greater the efficacy of such induction, upon which depends not only the law of causation but the principles of number and geometry. If the 'subject-matter of any generalisation' be so widely diffused that it can be tested at every time and place, and if it 'be never found otherwise than true' its truth cannot depend on any collocations, unless such as exist at all times and places, nor can it be frustrated by any counteracting agencies except such as never actually occur.'(87*) Now no exception to the 'law of causation' has ever been found, and apparent exceptions have only confirmed it. It is no doubt true that if a law be universal, it will be confirmed by all our experiments; but it hardly follows that, because all our experiments have failed to detect an exception, it is true universally. All our experiments have covered but a small fragment of nature, and they do not justify us, as he expressly asserts, in reasoning about the stellar regions. It is difficult, moreover, to see how an 'exception' could ever be proved, since, wherever we do not see a 'cause,' we can always suppose, and do in fact suppose, an invisible cause. Finally, the theory of 'natural kinds,' as it has now been interpreted, seems to fail us in our need. He takes it to indicate, indeed, that there are connections in nature, which, if known, would justify certain general inferences; but it does not appear that we can know what are these connections, and as, moreover, we have been carefully told that they are ultimate or not 'derivative,' we have no right to be certain that they will recur. We do not know, for example, whether blackness be a property of kind. If we found a black crow among white ones, the property would be casual, and therefore 'caused.' If we found a race of white crows in Australia, we should simply say that there was a kind hitherto overlooked.(88*) Such a discovery, he says, is not at all incredible. It might be proved by the evidence of a single credible witness. It merely supposes that there is a kind with a different set of attributes, and as the attributes are in no way 'derivative,' there is no improbability in this. The more general the rule, however, the greater the probability of its holding, because the greater the improbability of the exception being overlooked. We should easily believe in white crows, but not so easily in crows with a property 'at variance with any generally recognised universal property of birds,' and still less, if it were 'at variance with such a property of animals.'(89*) We could hardly, that is, believe in crows with the stomachs of wolves, or in crows without stomachs at all. But the difficulty appears to depend upon nothing else than the improbability that such animals, had they existed, would have been unnoticed. Without trying fully to unravel this logic, we may notice one characteristic. Mill, trying to refer everything to 'experience,' has gone far to make experience impossible. What has dropped out of this theory of knowledge is the constructive part. He substitutes for organisation combinations of disparate 'things.' He will admit of no logic, except that. of an external connection of radically different objects. Attributes must be stuck together without any reciprocal relations. All causation becomes in his phrase 'collocation,' though he declares causation and collocation to be not only different but mutually exclusive. His one logical formula is the nota notae est nota rei ipsius.(90*) Things are marks of each other, not implied by each other. He forces this language even upon mathematics. Even a geometrical 'kind,' if we may use the word, an ellipse, or a curve of the second order, is treated by the formula applicable to purely empirical conjunctions. The equality of two straight lines, it seems, is simply a 'mark' that if applied to each other they would coincide; the fact that two things are sums of equals is a 'mark' that they are equal, and so forth.(91*) He would apparently be inclined to say that a thing's existence is a mark of its not being nothing. Thus, even the 'natural kind' becomes merely a permanent combination. When the properties of a curve are merely connected by 'marks,' it is no wonder that the properties of crows should be mere bundles. If it is only on such terms that we can thoroughly get rid of 'intuitions,' the advantage is doubtful. I will venture to say another word upon the uniformity of Nature difficulty. It is easy, says Mill, to conceive of things happening at random. It is, indeed, in one sense perfectly easy. 'Raw' things, or unanalysed concrete events, do happen at random, that is, without uniform antecedents. Nothing is easier than to think of things without thinking of their causes. The primitive mind, and even the cultivated mind, may simply watch the series of events without trying to find any connection or indulging in any reasoning. But this is quite different from thinking of things as positively uncaused. A phenomenon suddenly intrudes without warning. I may accept it without asking whence it comes, or why. But there is no really positive meaning in the statement that it is caused by 'nothing.' It does not imply a contradiction, such as occurs when I put together the words crooked and straight, round and square; but it represents no intelligible meaning. It corresponds to a simple absence of thought. When I speak of the uniformity of Nature, I mean simply to indicate a condition of thinking about Nature at all. I may cease to reason or to think; but if I think, I must think coherently, and assume what has been called the 'Universal Postulate.'(92*) The phrase seems to me to be inadequate; and at any rate it is a postulate with this peculiarity, that we cannot make any other. To deny it is to allow contradictory statements on the most intimate tissue of our reasoning. It is as impossible to do without it as to do without the principle of contradiction in pure logic. It helps us to no positive statement; but it is a warning that our statements must be coherent. Hence, we must allow the mind to have this modest capacity for working up its experience. If it starts from so unprejudiced a point of view as to admit contradictions, or allow of inconsistent statements about things, it will never be able to get anywhere, and when Mill has reduced all our knowledge to the relations between ideas in the mind, it is really quite inconsistent to allow the mind no power of putting ideas together. Without such a power it is difficult to say what is even meant by the perception of 'coexistences' and 'sequences.' The progress of knowledge, then, must be understood as corresponding to the process by which the chaos of impressions and ideas is gradually reduced to cosmos; and as starting from a position in which no cause has been yet discovered for great masses of facts, not from a position in which 'no cause' is an equally probable alternative with 'some cause.' To reason at all about facts is to arrange them in order of causation, and to suppose them as having certain time- and space-relations. To get behind that primitive germ of reasoning is really to make logic impossible from the start. Mill's dread of a priori intuitions and necessary results thus led him into perfectly gratuitous difficulties. Granting the 'necessity' of arithmetic or geometry, it is still a hypothetical necessity. It can never take us beyond experience. Such theorems cannot tell us of the existence of a single thing or of its nature. They can only say that if we see things in space they will have certain relations which are deducible from the special confirmation. Without that power the universe would be undecipherable, but with it our knowledge still has throughout a completely empirical base. Not a single statement of fact can be made which is not derived from, and justified by, experience; nor can our experience ever get beyond saying that any given section of the whole is developed out of, and develops into, preceding and succeeding sections. VIII. THE FOUR METHODS I have dwelt upon these misconceptions to show why Mill was driven in defence of experience to assume the burthen of proving paradoxes which would be destructive to our very capacity for obtaining experience. Mill prided himself with some reason on his 'four methods.' Although they have been severely criticised,(93*) they have, I take it, a genuine value; and, if we ask how they can be valuable in spite of his errors, a satisfactory answer may perhaps be given. In the first place, his assumptions represent one genuine 'moment' in all reasoning about facts. The primitive intellect may be supposed to regard facts as simply conjoined, and to be guided by 'association of ideas.' The early generalisations of which Mill speaks -- 'fire burns,' 'water drowns,' and so forth are really of this kind, and are apparently formed even by dogs and monkeys. Mill is quite right, moreover, in holding that a purely empirical element runs through the whole fabric of knowledge. The error, I think, is in his failure to allow for the way in which it is modified in scientific construction. The ultimate element out of which that construction is developed is always an observation of fact, but the fact means a definite relation of time and space. We start from a 'fact,' but it is not as a simple unanalysable unit, but as something which already is the base of a relation. The unit which corresponds to the final cell out of which tissue is composed is not properly a fact, but a 'truth.' We do not say simply 'this is,' but this is so and so, and has a certain order and configuration. This is gradually elaborated into physical science by the help of the geometrical and numerical relations already implied. Thus, causation, or the connection between phenomena, is not simple collocation, but supposes continuity. The unconditional sequence which Mill identifies with 'causation' does not, and cannot, give the 'cause,' though it does indicate 'causal connection.' So long as two things are entirely separate and distinguishable, we cannot say, in the full sense, that one is the cause of the other; but the connection, if proved, proves that there is a cause which may or may not be discoverable. Brown was right in thinking that something was still wanting, though his mode of filling the gap by an intuition was erroneous. Mill's answer that the 'intuition' was needless left the difficulty where Hume had put it. Two facts are supposed to be unrelated and yet always combined. That states a difficulty, and only pronounces it to be insoluble. It has, in fact, to be surmounted by scientific hypotheses. Thunder and lightning, for example, are causally connected, but not so that lightning can be properly called the cause of thunder. They are regarded as due to a common cause to the processes which we call electric disturbance, and so forth. We cannot give the 'law' or state the casual connection adequately, but we regard them as indicating some common element, which is continuous and capable of being described in terms of pure number and geometry. Hence any observation, as soon as we begin to reason, may be regarded as a particular case of some general law, or rather, as being conceivably a case of an indefinite number of laws. Not only so, but any law under which it may be arranged is 'necessary' if all the conditions be restored. The process by which we select one of the possible formula, therefore, comes to eliminating all the formula which are incorrect when various conditions are altered. We all along assume that some coherent system of 'laws' is possible, or that the rule is there if only we can discover it. If lightning goes once with thunder, we are entitled to say not only that it may go with thunder hereafter, but that it must go with thunder under the same conditions. Therefore the simple inference from an empirical conjunction is justified by the 'law of causation' or the 'uniformity of nature.' Now, Mill's 'four methods' are applicable to the merely empirical conjunctions, which form a large part of our knowledge, and are implied in every stage. The methods do, in fact, I take it, form an approximately accurate mode of dealing with such knowledge. His cases are, for the most part, selected from the sciences, chemistry in particular, where in point of fact our knowledge is still purely empirical, and we can only assert a collocation, or sequence, without bringing it under a more general rule. He also observes, and the remark must be remembered, that he is trying to give a method of proof, rather than of discovery.(94*) If the scientific theory be true, these purely empirical truths will hold good, although from them alone the theory might not have been discoverable. The phenomenon which we call the fall of a stone will be presented when an unsupported stone is near the earth, although the law of gravitation requires an application of methods not summed up by simple observation of conjoined phenomena. The most unsatisfactory part of the 'four methods' results from this view.(95*) The process of discovery is not sufficiently represented by the case of A occurring with or without B. The sciences which have risen to be quantitative advance by showing how a variety of cases can be brought within some general and precise formula, and every approximation to, or deviation from, the law be exactly measured. Mill pays too little attention to this essential characteristic, partly, perhaps, because he considers mathematics as simply one part of the 'inductive' or empirical sciences. The final position may be shortly illustrated by Mill's relation to his contemporaries. It will show briefly what were the alternatives between which he had to choose, and that, if that which he chose leads to error, there were at least equal errors on the other side. Mill frankly states in his preface that but for Whewell's History of the Inductive Sciences the corresponding part of his own book 'would probably not have been written.' He remarks with equal candour that Sir John Herschel, in his Discourse on the Study of Natural Philosophy,(96*) had recognised the four methods. Herschel, however, was his only predecessor, and a more distinct and articulate exhibition of their nature was desirable. Herschel and Whewell had graduated at Cambridge in 1813 and 1816. Both of them were able mathematicians, and, with their contemporary Babbage, had done much to introduce at their university the methods of analysis developed on the Continent. The university was gradually roused; Herschel won a great name in astronomy, and Whewell took in earlier life a very active part in promoting scientific studies in England.(97*) Both of them had much closer acquaintance with the physical sciences than Mill, for whom they provided a useful store of materials. Herschel, though a friend of Whewell, approximates to Mill. A 'famous' review of Whewell's two books in the Quarterly of June 1841(98*) gives his position; but although he seems to perceive the source of Whewell's weakness, he scarcely comes to close quarters. It is enough for my purpose to speak briefly of the points at issue between Mill and Whewell. Whewell, like his most eminent contemporaries at Cambridge, was becoming aware that German speculation could no longer be overlooked. Herschel was son of a German; and Whewell's friends, Julius Hare (1795-1855) and Connop Thirlwall (1797-1875) were taking up the study of German. Their translation of Niebuhr's History of Rome (1828-1832) marked an epoch in English scholarship. Whewell meanwhile had read Kant, and been greatly impressed. Especially, as he says, he accepted Kant's theories of space, time, and, in some degree, causation, although he differed from Kant's doctrine as to other so-called 'fundamental ideas.'(99*) He 'gladly acknowledges,' too, his obligations to the Scottish school.(100*) In fact, it may be said that, like Sir W. Hamilton, he made a compromise between two modes of thought which very rapidly diverge from each other. Whewell begins his Philosophy of the Inductive Sciences by considering the fundamental antithesis of philosophy, which corresponds to the distinction between thoughts and things, necessity and experience, object and subject, and so forth. Time and space are, in his phrase, 'fundamental ideas,' upon which are founded the mathematical sciences. But there are other 'fundamental ideas' -- 'cause,' 'media,' 'polarity,' 'chemical affinity resemblance,' 'excitability,' and 'final cause' -- which in succession become the foundation of various sciences. These fundamental ideas are, as he admits, something like 'innate ideas,' except that they can be 'developed.' They can somehow be 'superinduced upon facts,' and are not 'generated by experience.' I shall not attempt to explain a theory which seems to be radically incoherent, and which made no converts. It will be quite enough to notice two of the points of collision with Mill. Mill and Whewell agree(101*) that the 'first law of motion' which asserts the uniform rectilinear motion of a body not acted upon by a force was unknown till the time of Galileo. Whewell admits further that, 'historically speaking,' it was made 'by means of experiment.' We have, however, attained a point of view in which we ae that it might have been certainly known to be true, independently of experience, Mill naturally ridicules this doctrine, according to which we burden ourselves with 'truths independent of experience' and yet admit that they were proved 'by (or 'by means of') experiment.' The history is admitted on both sides. It had been observed that the motion of all bodies ceases unless they receive a new impulse. The statement was true, though vague, for all bodies upon the earth. But the progress of astronomy and exact sciences required a more precise statement. Science has not simply to recognise that motion declines, but to show at what rate, and under what conditions it declines. Then, as we cannot measure 'absolute motion,' or assign any fixed point in space, we can obtain no rule as to absolute motion. If we assume, however, that we have to account not for motion but for change of motion, we can get a consistent 'law' which at once gives a sufficient account of many observed phenomena. We proceed to define force as the cause of change in motion. Then it becomes an identical proposition that all change of motion implies force, or that bodies not acted upon continue to move uniformly. Thus the definition of force takes the shape of an a priori axiom as to force. We imagine that instead of simply co-ordinating our experience we are 'applying a fundamental idea' to it, the idea, namely, of a 'cause' or 'force.'(102*) The axiom is not 'independent of experience.' Rightly understood, the whole process is one of interpreting experience. Mill, however, is hardly correct in saying that the law was proved by experiment. We cannot observe a 'force' apart from the moving body. Force is one of Bentham's 'fictitious entities,' a word which enables us to state the relations of moving bodies accurately. It harmonises our conceptions. The old belief that all motions stop is not disproved by discovering cases in which force is absent, but by postulating the presence of force wherever we find change of motion. The real proof is not in direct experiment but in the harmonising of an indefinite number of complex statements when once the principle is systematically applied. It can reveal no fact to us, for nothing but experience can show that there are such things as the planets fortunately are, bodies moving freely, so as to illustrate the law continuously. Mill puts the first law of motion on a level with the law that the period of the earth's rotation is uniform. Both 'inductions,' he says, are accurately true.(103*) In fact, however, the earth's motion is not absolutely uniform, a truth which we discover by applying the laws of motion, though no direct experiment could exhibit the fact. The law of motion has the authority derived from its rendering possible a consistent interpretation of experiences, whereas the earth's rotation is simply a particular fact which might change if the conditions were altered. The 'law' implies, therefore, a reconstruction of experience not given by simple observation. This applies to a controversy between Mill and Whewell as to Kepler's great discoveries. They both accept the familiar facts. Kepler's problem was to show how a simple configuration of the solar system would present the complex appearances which we directly observe. The old observations gave approximately correct statements of the movements of the planets, assuming the earth to be fixed, or, as we may say, neglecting the consideration of its motion. His theory shows how the apparent movements must result if we suppose the sun to be fixed, or rather (as the sun is not really fixed) if we measure from it as fixed. Whewell treats this as a case of 'induction.' It illustrates what he calls the 'colligation of facts' -- a happy phrase, accepted by Mill, for the arrangement of facts in a new order, and the application to the facts of the appropriate conceptions; in this case, of the theorems of conic sections and solid geometry. The argument takes the form of a discussion as to whether this should be called induction or an operation subsidiary to induction.(104*) Kepler, as Mill urges, was simply describing facts. He discovered a fact in which all the positions of the planet agreed -- namely, that they were in an ellipse. If he had been somewhere in space, or the planet had left a visible track, he might have actually seen it to be an ellipse. He had only to 'piece together' his observations, as a man who sails round an island discovers its insularity. The only induction, then, was that as Mars had been in an ellipse he would stay in an ellipse. Apart from the verbal question whether the process be rightly called induction or subsidiary to induction, the real issue is in Mill's complaint that Whewell supposed a 'conception to be something added to the facts.' The conception, Mill admits, is in the mind, but it must be a conception of 'something in the facts.' The ellipse was in the facts before Kepler saw it. He did not put it, but found it there. Whether Kepler's process was inductive or deductive or subsidiary, it was an essential part of scientific investigation. The man of science must, as Mill truly says, interpret the facts, and nothing but the facts; he must also, as Whewell truly replies, 'colligate' or arrange the facts in a new order. The constructive process which justifies me in saying this is an island, or this is an ellipse, is precisely what makes scientific knowledge possible, and involves something more than a mere putting together of raw fact. Every fact, as Whewell sees, may be regarded as a case of countless laws, each of which may be true under appropriate conditions. To eliminate the irrelevant, to organise the whole system of truths, so as to make the order of nature (as Mill forcibly says (105*)) deducible from the smallest possible number of general propositions, is the aim of science; and Mill obscures this so far as he regards such operations as Kepler's as mere observations of fact, in such a sense as to omit the necessity of a new organisation of the data. I have gone into some detail in order to show what was the essential characteristic of Mill's doctrine, which was itself, as I have said, an explicit statement of the principles implicitly assumed by his predecessors in the same school. To do him full justice, it would be necessary to show what was the alternative presented by his opponents. The Scottish writers and Whewell brought back 'innate ideas,' or endeavoured to connect knowledge by beliefs and intuitions arbitrarily inserted into the fabric as a kind of supernatural revelation. To explain these intuitive dogmas into effects of 'association' was the natural retort. Meanwhile the transcendental school was taking the bolder line of rejecting experience altogether, treating it with contempt as a mere rope of sand, and inferring that the universe itself is incarnate logic -- a complex web woven out of dialectic, and capable of being evolved from mixing 'is' and 'is not.' To Mill this appeared rightly, as I should say, to be mysticism and ontology, or a chimerical attempt to get rid of the inevitable conditions of all knowledge of reality. The real problem of metaphysics appears to be the discovery of the right method of statement, which will explain what appeared to be the insoluble antithesis between empiricism and intuitionism (to take Mill's phrase), and show that they are attempts to formulate correlative and essential truths. IX. THE MORAL SCIENCES Happily, philosophical theories are not really important solely as giving tenable and definitive results, but as indications of the intellectual temperament of different schools, and of the methods of reasoning which they find congenial. Without further disquisition, I shall conclude by indicating briefly Mill's application of his principles to the 'Moral Sciences.' This is the subject of the last book of his treatise, and represents, as we have seen, the purpose of the whole. As, however, the full application will appear hereafter, I may here confine myself to certain critical points. Mill begins of course by arguing that the 'Moral Sciences' are possible, and are to be created by applying the method of the physical sciences. This suggests the free will difficulty. The doctrine of 'philosophical necessity' had 'weighed on his existence like an incubus' during his early depression.(106*) He escaped by the solution which now forms a chapter in the Logic. He discovered that the Hume and Brown theory removed the misleading associations with the word 'necessity.' It would be truer, he thinks, to say that matter is free than that mind is not free.(107*) The supposed external 'tie' which binds things together is a nonentity. In practice, however, Owen and his like had become fatalists rather than necessitarians. Holding that character is formed by circumstances, they had forgotten that our own desires are part of the 'circumstances,' and therefore that the mind has the power to co-operate in the 'formation of its own character.' This, Mill thinks, is the ennobling belief which is completely reconcilable with the admission that human actions are caused, although the two doctrines had been on both sides regarded as incompatible. Upon this endless controversy I can only suggest one hint. Mill, I think, was right in saying that the difficulty depends on the confusion of 'determinism' with 'fatalism'. that is, with the belief that the will is coerced by some external force. But he does not see that his doctrine of causation always raises the difficulty. He orders us to think of the succession of ideas as due simply to association, as in the external world events are to be regarded as simply following each other; and in either case it is impossible to avoid the impression that there must be some connecting link which binds together entirely disparate phenomena. We cannot help asking why 'this' should always follow 'that,' and inferring that there is something more than a bare sequence. The real line of escape is, I think, shown by an improved view of causation. If we hold that the theory of cause and effect simply arises from the analysis of a single process, we need no external force to act upon the will. There is no 'coercion' involved. Given the effect, there must have been the cause; as given the cause, the effect must follow. 'All the universe must exist in order that I must exist' is as true as that 'I must exist if all the universe exists.' There is not a man plus a law, but the law is already implied in the man; or the distinction of cause and effect corresponds to a difference in our way of regarding the facts, and implies no addition to the facts. I must not, however, launch into this inquiry. I only note that Mill's view is connected with his favourite principle of the indefinite modifiability of character.(108*) To Mill, as to his father, this seemed to hold out hopes for the 'unlimited possibility' of elevating the race. If J. S. Mill denied 'the freedom of the will,' or, rather, the existence of 'will' itself as a separate entity, actually originating active principles, he admitted that the desires erroneously hypostatised as 'will' could work wonders. As the causal link between events is a figment, so, in the sphere of mind, we are bound by no fixed mysterious tie. He thus escapes from the painful sense of coercion by holding that an infinite variety of results is made possible by the infinite combinations of materials, though, in each case, there is a necessary sequence. Association, in fact, is omnipotent. As it can make the so-called necessary truths, it can transform the very essence of character. Accordingly the foundation of the moral sciences is to be found in the psychology, for an exposition of which he refers to his father, to Mr Bain, and to Mr Herbert Spencer.(109*) He thus drops, consciously or not, the claim of treating metaphysical doctrine as common ground, and assumes the truth of the association doctrine. To pass from these principles to questions of actual conduct requires a science not hitherto constructed -- the science, namely, of human character, for which he proposes the name Ethology. This, as we have seen, occupied his thoughts for some time, till it was ultimately dropped for political economy. The difficulty of forming such a science upon his terms is obvious. It holds an ambiguous place between 'psychology' and the 'sociology' which he afterwards accepts from Comte; and as Professor Bain remarks, his doctrine would not fit easily to any such science. He has got rid of 'necessity' only too completely. In fact, his view of the indefinite power of association, and his strong desire to explain all differences, even those between the sexes, as due to outward circumstances, seem to make character too evanescent a phenomenon to be subjected to any definite laws.(110*) Ethology, however, is taken by him to be the science which corresponds to the 'art of education,' taken in its widest sense, and would, if constructed, be a 'deductive science,' consisting of corollaries from psychology, the 'experimental science.'(111*) The utility of such a science from his point of view is obvious. It would be a statement of the way in which society was actually to be built up out of the clusters of associated ideas, held together by the unit Man. His method in 'moral science' follows the lines now laid down. All inference, as he has urged, consists of 'inductions' and 'the interpretation of inductions.'(112*) Deduction is the application to new cases of the laws observed in previous cases. As our knowledge of such laws multiplies, science tends to become more deductive. But the deduction is still an induction; and the true antithesis is not between deductive and inductive but between 'deductive and experimental.'(113*) Deductive reasoning, that is, simply applies a previous induction; but reasoning becomes 'experimental' when we have to interrogate nature for a fresh rule. This has an important bearing upon the next step. Social phenomena of all kinds are so complex that we cannot apply his four methods. They belong to the region (in his phraseology) of the 'intermixture of laws' and 'plurality of causes';(114*) and though the phrases be inaccurate, the example certainly illustrates their plausibility. Experimental reasoning is thus impossible. We have, therefore, to fall back upon the 'deductive' method, which, indeed, would lead to mere 'conjecture' were it not for the essential aid of Verification.(115*) The meaning of this is explained in two chapters really directed against Macaulay and James Mill, and giving the theory which had been suggested by their controversy.(116*) Macaulay used the 'chemical' method. If men in society formed a new product differing from the individual man, as water from oxygen and hydrogen, or, in Mill's phrase, if the social union afforded 'heteropathic' laws, we should have to study social science apart from the science of individual human nature. But as men even in society are still men, the social law is derivable from the laws of individual nature. It is a case of 'composition of causes.' Now the purely empirical reasoner neglects this obvious fact. He reasons from immediate experience without connecting his conclusions with psychology. He argues offhand that because the English have flourished under the old parliamentary system, therefore the old parliamentary system was perfect. That gives the crude empiricism preached by Macaulay in the name of Bacon. James Mill, on the contrary, represents the 'geometrical method.' He argued about politics as if all constitutional questions could be settled like a geometrical problem by appeals to a single axiom. Therefore a doctrine applicable to the immediate question of parliamentary reform was put forward as a general theory of government. Mill tells us in the Autobiography(117*) that his reflection upon this controversy led to a critical point of his doctrine. Science must be deductive, when the effects are simply the sum of those due to the operating causes; inductive, when they are not the sum, that is, when 'heteropathic' laws appear. Hence, he inferred, politics must be treated deductively, though not as his father had done, geometrically. Both the criticisms are much to the purpose. Here I need only remark one point which affects Mill's later conclusions. Was Mill's inference correct? Is it true that the social phenomena represent simply the sum of the individual actions? Undoubtedly, there is a good deal to be said for it. Society does not exist apart from the individuals of which it is constructed. Moreover, in a great many cases, if we know the average character of an individual, we can deduce the character of a number of individuals. The bulk of what is called knowledge of the world is made up from more or less shrewd conjectures as to the motives of the average man. If we know what the average man thinks, we can guess what will be the opinion of a majority of the House of Commons. There are, however, two points which are taken for granted. In the first place, if we are to deduce the social phenomena from the individual, we must know the individual, who is already a tolerably complex product. In Mill's language, we require an ethology. and the name already indicates a difficulty. Can we consider the average man to be a constant? or must we not take into account the fact that he is also a product of society, and varies upon our hands as society develops? And beyond this there is the further question, whether, in so far as society can be properly regarded as an 'organism,' we can fully explain the laws of social combination by considering the laws of individual character. Are not the two sets of laws so intricately combined and blended that the analysis of a society into separate individuals becomes necessarily illusory? Can we explain the reciprocal actions and reactions of a social body by simply adding together the laws of individual conduct? These questions will meet us in considering Mill's practical application of his theories. They amount to asking whether 'sociology' can be constituted from a purely 'individualist' basis, and Mill's view of sociology is a vital point in his doctrine. The name had already been invented by Comte, and Mill at this time was greatly influenced by Comte, and especially was kindled to enthusiasm by the last two volumes of the Philosophie Positive, containing a connected view of history. Although Mill had, as he says, worked out his theory of induction before reading Comte, he owed a great deal, as he fully acknowledges, to Comte's philosophy. The two lines of thought, however, could never completely coalesce, and the result appears in this part of Mill's book. Admitting a deductive method to be necessary, Mill distinguishes the 'direct' and the 'inverse methods.'(118*) The direct method is that of reasoning from one 'law of human nature,' considering, of course, the outward circumstances. This justifies the system of political economy, which considers men as acting solely from the desire of wealth. He points out that fallacies may here arise from applying to one state of society what is true of another; but he also holds that one who knows the political economy of England, or even of Yorkshire, knows that of all nations, if he have good sense enough to modify his conclusions.(119*) Mill admits fully that this method can only give us 'tendencies' -- results which are true if certain conditions, never fully assignable, are actually secured; and that it therefore requires to be constantly checked by verification, that is, by showing that the results are confirmed by direct observation. The admission, however, that such a method is in any case admissible separates him from Comte, who held that we must in all cases start from historical generalisations, not from independent 'laws of human nature.'(120*) Comte, in fact, rejected Mill's psychology and political economy as pseudo-sciences, and the difference is really vital. Mill, however, was prepared to accept much of Comte's teaching, and in particular allows the legitimacy of the 'historical method.' Upon this he writes a chapter,(121*) which shows no want of appreciation of Comte or of the great French writers by whom, as his Dissertations show, he had been deeply impressed.(122*) He complains of the English want of interest in such matters. They know nothing in French literature except the novels of Balzac and Eugène Sue, and are not aware that the French historians greatly surpass even the Germans.(123*) He points out the importance of the conception of progress and of the great modifications of human character. Still, he charges the French with a misconception. History can never give us a 'law of nature,' only 'empirical laws,' which are not scientific till duly based upon psychology and 'ethology.' Comte alone has seen the necessity of a deeper foundation; and he proceeds to give an admiring account of some of Comte's conclusions. Especially he insists upon the necessity of connecting the social phenomena with the intellectual development of mankind. This Comte alone has attempted systematically, and he ends by emphatically adhering to the doctrine of the three stages -- theological, metaphysical, and positive. The essential difference, however, remains. Comte held that we must not explain humanity by man, but man by humanity.(124*) To Mill, of course, this savoured of mysticism. In any case, it marks the divergence of the two: Mill is a thorough individualist. He thinks it absolutely necessary to base sociology upon 'ethology,' that is, a theory of the individual character, and this again must be based upon psychology. Sympathising with Comte's general purpose, and warmly admiring some of his results, Mill adheres to a doctrine which was sure to bring him into conflict with his master. To create the moral sciences, we must start from a scientific psychology. This means that we must work on the lines of Hartley, James Mill, and his own younger contemporaries, Professor Bain and Mr Herbert Spencer. The corollary from psychology is ethology, or the science of character. This view does not conflict with the admission of the great importance of some historical method. At present, it needs only to be said that Mill accepts that method very cordially, subject to two conditions. First, he holds that some social sciences -- political economy being, in fact, the only one to be clearly specified -- can be deduced from ethology and psychology independently of history, though requiring verification from history. Secondly, he holds that the historical method cannot reveal true 'laws of nature' unless it is properly connected with psychological data. How far Mill really appreciated the significance of the historical method, or perceived its true relation to other departments of thought, must be left for consideration. NOTES: 1. Autobiography, p. 226. 2. Logic, p. 389 (bk. iii. ch. xxi, section 1). I quote from the popular edition of 1898. Book, chapter and section are generally applicable to former edition. 3. See letter in note to chapter upon Mill in Taine's History of English Literature. 4. James Mill's Analysis, i. 352 n. 5. See an interesting article in G. Croom Robertson's Philosophical Remains (1894), pp. 28-45. 6. Logic, Introduction, section 5. 7. Ibid., p. 29 (bk i, ch. iii, section 1). 8. Ibid., p. 8 section 7. 9. See John Grote's Exploratio Philosophica (1865), p. 209 n. This book is, I think, by far the most interesting comtemporary discussion of Mill, Hamilton, and Whewell. It was, unfortunately, desultory and unfinished, but it is full of acute criticism, and charmingly candid and modest. Mill's Logic is especially discussed in chapters viii and ix. Grote holds, and I think truly, that Mill's attempt to divide metaphysics from logic leads to real confusion, and especially to an untenable mode of conceiving the relation between 'things' and thoughts. I cannot discuss Grote's views; but the book is full of interesting suggestions though the result are rather vague. See the excellent account of Grote by the late Croom Robertson in the History of National Biography. 10. Mill, in his review of Whately, refers to Du Trieu (whose treatise had been privately printed by him and his friends), Crakenthorpe and Burgersdyk; and in the Examination of Hamilton's Philosophy (ch. xxii) quotes also Sanderson, Wallis, Aldrich, Keckermann, Bartholinus, and Du Hamel as the 'authorities nearest at hand'. There is nothing, as I am told by the learned, exceptionally interesting in Du Trieu; and the selection was probably accidental. 11. Logic, p. 13 (bk. i, ch. ii, section 1). 12. Ibid., p. 29 (bk. i, ch. iii, section 1). 13. Ibid., p. 49 (bk. i, ch. iii, section 15). 14. Ibid., p. 35 (bk. i, ch. iv, section 6). 15. Ibid., p. 38 (bk. i, ch. iv, section 7). 16. Logic, p. 40 (bk. i, ch. iv, section 8). 17. Ibid. p. 41 (bk. i, ch. iii, section 9). 18. Logic, p. 43 (bk. i, ch. iv, section 10). 19. Ibid., p. 68 (bk. i, ch. v, section 6). 20. Logic, p. 61 (bk. i, ch. v, section 3). 21. Ibid., p. 63 (bk. i, ch. v, section 4). 22. It would be interesting to compare this part of Mill with the corresponding part of Hume's Treatise. Hume, like Mill, begins by accepting causation as one of the relations involved, and then explains it as merely derivative. His treatment of relations generally, especially the division of relations into the two classes, which do or do not depend upon the 'ideas' themselves, has a bearing upon Mill's doctrine too intricate to be considered here. [Treatise of Human Nature, pt. vi. sec. 1.] I do not think that Mill was very familiar with Hume's writings. A note to the concluding chapter of the Examination of Hamilton seems to imply that he was not acquainted with the Treatise; nor does he appear from his posthumous Essays to have studied Hume's writings upon theology. Whether T.H. Green was right in holding that Hume had a more distinct view than his successor of some metaphysical difficulties, I need not inquire. 23. Logic, p. 70 (bk. i, ch. v, section 7). 24. Ibid. p. 434 (bk. iv, ch. iii, section 2 n.). 25. Logic, p. 132 (bk. ii. ch. v, section 4). 26. Especially the early review of Whately. 27. This suggests a parallel to the old English system of pleading -- as a preparatory process for bringing out the issues really involved in a dispute -- which is said to have been thoroughly logical, though it became excessively cumbrous and technical. 28. Logic, p. 327 (bk. v, ch. vi, section 3). So in Examination of Hamilton, ch. xxii., 'The syllogism is not the form in which we necessarily reason, but a test of reasoning.' 29. James Mill's Analysis, ii. 427. 30. Logic, p. 131. (bk. ii, ch. iii, section 5). 31. Logic, p. 72 (bk. i, ch. vi, section 2). 32. Ibid. p. 113 (bk. ii, ch. ii, section 5). 33. Autobiography, p. 181. The passage to which Mill refers is apparently that in Stewart's Works, iii, 24-36 and 113-52. Stewart quotes a passage from Dr Beddoes' Observations on the Nature of Demonstrative Evidence (1793), which anticipates Mill's view that the 'mathematical sciences are sciences of experiment and observation, founded solely on the induction of particular facts.' Stewart professes to follow Locke (see Locke's Essay, bk. iv, ch. xii, section 15), and gives some references to other discussions on the questions. 34. Logic, p. 94 (bk. i, ch. viii, section 5). 35. Logic, p. 125 (bk. ii, ch. iii, section 3). 36. Logic, p. 126 (bk. ii, ch. iii, section 4). 37. Ibid. p. 107 (bk. ii, ch. i, section 3). 38. Whiston (Memoirs, i, 35) reports that Newton saw by intuition, or previously to formal demonstration, the equality of all parallelograms described about the conjugate diameters of an ellipse. Most of us can only learn the fact by painful construction. 39. Hume's Works (Grose and Green), ii, 432 and iv, 134. Hume's statement is criticised by G.H. Lewes in his Problems, etc. i, 391, but, I think, on an erroneous interpretation. 40. Logic, p. 149 (bk. ii, ch. v. section 1). 41. Ibid. p. 151 (bk. ii. ch. v. section 4). 42. Ibid. p. 147 (bk. ii. ch. v. section 1). 43. Ibid. p. 183 (bk. ii. ch. vii section 5). In the Examination of Hamilton he is less confident. It is 'not only inconceivable to us, but inconceivable that it should be mad conceivable' that the same statement should be both true and false (ch. vi. p. 67). Afterwards (ch. xxi. p. 418) he will only decide that such laws are now 'invincibly' laws of thought, though they may or may not be 'capable of alteration by experience.' 44. Logic, p. 148 (bk. ii. ch. v. section 1). 45. Ibid. p. 168 (bk. ii. ch. vi. section 2). 46. Ibid. p. 400 (bk. iii. ch. xxiv. section 5). 47. Ibid. p. 401 (bk. iii. ch. xxiv. section 5). 48. Ibid. p. 170 (bk. ii. ch. vi. section 3). 49. Ibid. p. 167 (bk. ii. ch. vi. section 2). 50. Logic, p. 212 (bk. iii. ch. v. section 1). 51. Logic, p. 401 (bk. iii. ch. xxiv. section 6). 52. Logic, fourth edition, i. 356 (bk. iii. ch. v. section 1). This phase is omitted in the last edition (p. 211), but the meaning is apparently not altered. 53. Ibid. p. 399 (bk. iii. ch. xxiv. section 5). 54. See Logic, p. 177 (bk. ii. ch. vii. section 3), and p. 493 (bk. v. ch. ii. section 3). 55. Ibid. p. 370 (bk. ii. ch. xxi. section 1). 56. Logic, p. 206 (bk. iii. ch. iii. section 3). 57. Ibid. p. 213 (bk. iii. ch. v. section 2). 58. Logic, bk. iii. ch. v. 59. Ibid. p. 217 (bk. iii. ch. v. section 3). 60. Logic, p. 221 (bk. iii. ch. v. section 5). 61. Ibid. p. 227 (bk. iii. ch. v. section 8). 62. Ibid. p. 224 (bk. iii. ch. v. section 7). 63. Logic, p. 243 (bk. iii. ch. vi. section 1). 64. Logic, p. 245 (bk. iii. ch. vi. section 2). 65. Grove's work was first published in 1846, i.e. after the first edition of the Logic. 66. Logic, fourth edition, p. 477 (bk. iii. ch. x. section 4). In the eighth edition this passage was suppressed, and Mill discusses the theory of 'conservation or persistence of force," as he calls it, in an earlier section. -- Logic, p. 228 (bk. iii. ch. v. section 10). 67. Logic, p. 501 (bk. v. ch. iii. section 8). 68. See, for example, his criticism of a 'luminiferous ether' in answer to Whewell, Logic, p. 328 (bk. iii. ch. xiv. section 6). He agrees here with Comte (Phil. Positive, ii. 639), whom he perhaps follows. 69. See especially the chapter on causation in the Examination of Hamilton. 70. Tyndall, e.g., in his Heat as a Mode of Motion, quotes Bacon's anticipation. It is summed up by Whewell (Phil. Ind. ii., Sciences, ii. 239) in the statement that the 'form of heat is an expansive, restrained motion, modified in certain ways, and exerted in the smaller particles of the body.' 71. Logic, p. 500 (bk. v. ch. iii. section 7). 72. Logic, p. 288 (bk. iii. ch. x. section 3). 73. Logic, p. 500 (bk. v. ch. iii section 7). It may be noted that Whewell (in 1847) equally regards Bacon's theory as a complete failure. He thinks more favourably of an 'imponderable fluid.' Mill, therefore, had good authority as to the failure. The modern doctrine, says Lord Kelvin (Encycl. Britannica), was established about 1851. See Huxley on the 'Progress of Science' (Essays, i. 86) for Whewell's treatment of Bacon's guess. 74. Logic, p. 226 (bk. iii. ch. v. section 7). 75. Logic, p. 306 (bk. iii. ch. xii. section 2). See Chalmer's Natural Theology, bk. ii. ch. i. 76. Logic, pp. 377-85 (bk. iii. ch. xxii). 77. Logic, pp. 79-81 (bk. i. ch. vii. section 4). 78. Logic, pp. 377-86 (bk. iii. ch. xxii). 79. It has been suggested that upon Mill's principles the change of a lobster's colour to red is 'caused' when he is boiled, but the colour before boiling uncaused. A case in the South Kensington Museum showing variously coloured crows is a tacit comment on Mill's illustration. The colour of crows is obviously considered by modern men of science as implying causal relations. 80. Logic, p. 382 (bk. iii. ch. xxii. section 6). 81. Ibid., p. 381 (bk. iii. ch. xxii. section 4). 82. Logic, p. 470 (bk. iv. ch. vii. section 4). It is curious that this remains in the last edition, that is, after the first Darwinian controversies. 83. See Sigwart's Logik (1889), ii. 456, etc. 84. Logic, pp. 370-76 (bk. iii. ch. xx. section 1, 4). 85. Ibid. p. 372 (bk. iii. ch. xxi. section 2). 86. Ibid. p. 373 (bk. iii. ch. xxi. section 3). 87. Logic, p. 382 (bk. iii. ch. xxii. section 5). 88. Ibid. p. 384 (bk. iii. ch. xxii. section 8). 89. As he says in the Examination of Hamilton, ch. xix. 90. Logic. p. 142 (bk. ii. ch. iv. section 4). 91. Some writers, especially G.H. Lewes, have tried to maintain that the statement of the uniformity of Nature is an 'identical proposition.' The attempt is unsatisfactory, and certainly does not seem to have found favour with later writers; but, though I am unable to discuss the question, I will suggest that it seems to indicate the ideal result of reasoning. We assume that, if our knowledge were complete, we could state all the laws of action and reaction of any element as necessary consequences of its primitive constitution, as we can deduce all the properties of number and space from primary principles. Though we can never attain such a consummation, we can reject any theory which contradicts it, and, therefore, such doctrines as the 'plurality of causes,' which come to supposing that an identical process may be analysed in two inconsistent ways. 92. E.g., by Mr F.H. Bradley in his Principles of Logic (1883), pp. 329-42. Dr Venn, who is much more favourable to Mill, discusses them in his Empirical or Inductive Logic (1889), pp. 400-31, shows very clearly how they assume what he calls the 'popular', as distinguished from the 'rigidly scientific', view of causation. Elsewhere (p. 58) he remarks that the popular might be called the 'Brown-Herschel-Mill view,' as those writers popularised the doctrine first clearly set forth by Hume. See also Sigwart's Logik (1889), ii. 469-500. 93. Logic, p. 284 (bk. iii. ch. ix. section 6). 94. Sigwart's Logik (1889) ii. 461. 95. Herschel's Discourse first appeared in 1830 as the first volume of Lardner's Cabinet Cyclopaedia. The 'four methods' are noticed, as Mill states, though with comparative vagueness, in chap. vi of the Discourse. Jevons prefers the statement to Mill's. Whewell makes the obvious remark (Philosophy of Discovery, p. 284) that the four methods resemble some of Bacon's Praerogative Instantiarum. 96. For Whewell, see the Writing so described as to form a biography by I. Todhunter (2 vols. 1876). The Life and Correspondence, by Mrs Stair Douglas, appeared in 1888. Whewell's chief philosophical works are: History of the Inductive Sciences (3 vols. 8vo, 1837; section edition, 1840; third edition, 1857); Philosophy of the Inductive Sciences (2 vols. 1840: second edition, 1857). This book was afterwards divided into three: -- History of Scientific Ideas, 2 vols. 1858; Novum Organum Renovatum, 1 vol. 1858; and Philosophy of Discovery, 1 vol. 1860. Whewell also wrote a pamphlet Of Induction with special reference to Mr J. Stuart Mill's 'System of Logic'. This is republished as chap. xxii of his Philosophy of Discovery. 97. Republished in Herschel's Essays (1857), pp. 142-256. 98. Scientific Ideas, i. 88 (note added to this edition). 99. Philosophy of the Inductive Sciences (1847), ii. 311. 100. Philosophy of the Inductive Sciences, i. 80. 101. Whewell's Philosophy of Inductive Sciences, i. 216-21; Mill's Logic, pp. 160, 265 (bk. ii. ch. v. section 6, and bk. iii. ch. viii. section 7). 102. Whewell, indeed, says that the 'necessary law' is that a change of velocity must have a cause; the 'empirical law' tells us that the time during which it has been moving is not a cause. -- Philosophy of the Inductive Sciences, ii. 591. I need not go into this. 103. Logic, p. 151 (bk. ii. ch. v. section 3). 104. Logic, p. 190, etc. (bk. iii. ch. ii. section 3, 4); Ibid. p. 423 (bk. iv. ch. i. section 4). 105. Logic, p. 207 (bk. iii. ch. iv. section 1). 106. Autobiography, pp. 168, 173. 107. Logic, p. 548 (bk. vi. ch. ii. section 2). 108. Autobiography, p. 108. 109. Logic, p. 557 (bk. vi. ch. iv. section 3). 110. See his view that the difference of character between the sexes is due to external circumstances, and therefore removable. -- Logic, p. 566 (bk. vi. ch. v. section 3). 111. Logic, pp. 567, 569 (bk. vi. ch. v. section 4, 5). (Art is misprinted 'act' in the last edition.) 112. Ibid. p. 185 (bk. iii. ch. i. section 1). 113. Logic. p. 144 (bk. ii. ch. iv. section 5). 114. Ibid. pp. 576, 585 (bk. vi. ch. vii. section 4; bk. iv. ch. ix. section 2). 115. Ibid, p. 303 (bk. iii. ch. xi. section 3). 116. Autobiography, p. 159. 117. Autobiography, p. 160. 118. Logic, p. 583 (bk. vi. ch. ix. section 1). 119. Ibid. p. 590 (bk. vi. ch. i. section 3). 120. Ibid. p. 584 (bk. vi. ch. ix. section 1). 121. Bk. vi. ch. x. 122. See especially the reviews of Tocqueville, Michelet, and Guizot in the Dissertations. 123. Dissertations, ii. 121. 124. Lettres inédites de Mill à Comte (1899), p. xxxv. Mill's letters to Comte upon his view of ethology are significant.