HAMILTON 419 facts but only as facts clear and certain, and as cognitions relative, more properly indeed, beliefs than cognitions, Hamilton claims for all that, on the sole authority of consciousness, they be accepted as truths. This is the point to which the tvhole of his philosophy leads up ; hence he offers no arguments in its support. He only asks If the authority of consciousness be dis allowed, what other warrant of truth remains ? Where else will a source of certainty be found ? He saw no alternative between ab solute scepticism and implicit reliance on consciousness. But his reliance was no absolute and blind belief. He claimed implicit cred ence for consciousness only after having investigated and laid down the conditions of its credibility. The inexplicanility that is to him a mark of truth must be proved to be that which springs from the fundamental character of the cognition. "While the establishment of principles on which belief may be sure, rational, and consistent is the ultimate aim of his philosophy, groundless or inconsistent belief he sweeps away wherever he meets with it. Thus he will not allow the validity of belief in an external reality which, ex hynothesi, is not known. 1 Be it noted too, that it is conscious ness, i.e., reason, for which he claims supreme authority. 2 His position is best understood through the mutual relation (already referred to) of his doctrines of the conditioned and of common sense*. The former extends the bounds of existence as much as it narrows those of thought, and so makes room for belief ; while the latter shows belief to be the condition on which alone even primary and fundamental truths can be apprehended. Thus, for example, on the ground of both, he held that freedom of will and necessity are alike inconceivable, but that we are not entitled to reject the testimony of consciousness to the fact that as moral agents we are free, on account of the speculative difficulties with which it is sur rounded. 3 These two doctrines Sir "W. Hamilton did not himself apply to theology, and in themselves they have no direct theological bearing, since the one is concerned with the infinite and the absolute merely as notions, and the other with simple forms of thought long prior to those of theology. But his references to this subject indi cate clearly what he considered to be the true relation of theology to philosophy, and show that, in the one as in the other, he held wisdom to lie in such a conviction of human ignorance as disposes the mind to accept harmony with the facts of consciousness as evidence of truth. 4 Of the three classes into which, as we have seen, Hamilton divided mental phenomena, the third the phenomena of conation is not treated of in his Lectures, and his other works contain only fragmentary discussions of particular ethical points. Several lectures, however, are devoted to the consideration of the pheno mena of feeling and the development of a theory of pleasure, founded chiefly on that of Aristotle, which is. in substance that pleasure is the reflex in consciousness of the spontaneous and unimpeded exer cise of power or energy, pain being, on the other hand, the con sciousness of overstrained or repressed exertion. 5 The logic with which Sir W. Hamilton s name is associated is a purely formal science. Nothing else indeed did he consider properly to be called logic. For it seemed to him an unscientific mixing together of heterogeneous elements to treat as parts of the same science the formal and the material conditions of knowledge. He was quite ready to allow that on this view logic cannot be used as a means of discovering or guaranteeing facts, even the most general, and expressly asserted that it has to do, not with the object ive validity, but only with the mutual relations, of judgments. He further held that induction and deduction are correlative processes of formal logic, each resting on the necessities of thought, and de riving thence its several laws. In establishing the distinction be tween logical and scientific induction, he showed that deduction no more than induction is self-sufficient, since it also must have a prior process to start from before it can be applied to nature. He also held that no other than formal logic can be distinguished from the body of the sciences. Perhaps he may have too much overlooked the fact that the search for causes (a problem common to all the sciences) and the presumable uniformity of nature (a principle capable of guaranteeing general inferences) yield the conditions of a logic entitled to the name of a science of science, and possessing all the im portance of the knowledge whose organon it is. Yet it is well to be reminded by a difference of name that a science such as this, consist ing of inferences from the actual order of things, is quite distinct from the body of truths developed from the conditions of thought as such. I he only logical laws recognized by Hamilton were the three axioms of identity, non-contradiction, and excluded middle, which 3 regarded as severally phases of one general condition of the . possibility of existence and, therefore, of thought. The law of ^ason and consequent he considered not as different, but merely as expressing metaphysically what these express logically. He added as a postulate which in his theory was of importance" that logic be allowed to state explicitly what is thought implicitly." ihe^changcs by which he to a great extent remodelled formal J Reid * Works, 755-770; Dise., 63. , H. 541-543; Dine., 98, 618-620. i L ec tt. ii. 414-WO. nr n, Di * e " 91 iq n V 5 ? 9 " 6 2 " 975 - 9S1 i Disc., 620 sg. Lects., ii. 530-535. logic were the result (1) of applying to propositions and syllogisms the two aspects of notions as wholes, extension, answering to the> objects denoted, and intension, answering to the attributes connoted, and (2) of assigning quantity to the predicate as well as to the subject in judgments of extension. These judgments receive the form of an equation. Only simple conversion is allowed, but, all propositions being shown to be capable of simple conversion, the class of immediate inferences is greatly increased. Categorical syllogisms (inductive and deductive) may be either unfigured or figured, according as the distinction of subject and predicate and the distinctions included in that are or are not recognized. Unfigured syllogism has but one form ; figured syllogisms are of three forms, according to the position of the middle term in the premises. Of these the first corresponds to the first and fourth figures of ordinary logic, the moods of the latter being shown to be merely indirect in tensive moods of the first. The laws of categorical syllogism are Te- duced to one. On the other hand, one of the results of the quantifi cation of the predicate being to increase the number of prepositional forms, a number of new moods are added, and each figure contains twelve. Hypothetical and disjunctive inferences, whether regarded as inediateoras immediate, (as to this Hamilton varied in opinion^ cf., Lects., iv. 369, 371, 373, 374), form a separate class of syllogisms, the conditional, properly subdivided into conjunctive and disjunctive ; for, according to Hamilton, as all inference is hypothetical, this term ought not to be used as the name of one particular group. The quantities allowed by him in logic were but two the defiuite, including the universal and singular, and the indefinite. The latter also he considered to "be twofold, partiality as such, from which the universal, both affirmative and negative; is excluded, and partiality which excludes only one universal extreme, while possibly admitting the other. All these improvements were embodied in a notation that clearly and compendiously presents to the eye the whole logical scheme. 6 Even from this imperfect outline of Hamilton s system of psychology, metaphysics, and logic it appears how ex tensive and original were his labours in the various depart ments of philosophy, how powerful an impetus he gave to speculation, and how much he himself contributed to the elucidation of the ultimate problems of thought. By his thorough-going analysis of consciousness and of the relation of consciousness to mind he did much to promote the scien tific study of psychology in his own country and in America, in particular to give it at once a sound method and a well-defined sphere. He did not himself trace the growth of consciousness ; but, by showing that it is both simple and complex, both involving and evolved, he implied that it had grown, and suggested the problem of the conditions of its development. On the other hand, to him there was a wide gulf between mental and material phenomena, and the acceptance of innate ideas was attended with no difficulty ; thus his point of view is so far removed from that of most of the psychologists of the present day that probably his in fluence now is much less either than it was in his own life time or than it may be hereafter. In metaphysics his place is plainly marked. Taking his stand at once on the exclusive authority and on the limited sphere of human consciousness, he comes into direct an tagonism with all schools of philosophy that find in the Unconditioned a field for speculation. At the same time he is divided from scepticism by his assertion that, as the realm of existence transcends that of thought, BO belief is wider than knowledge, and from empiricism by his admis sion of a priori and inexplicable cognitions. He ranked himself among the Scottish school of philosophers; yet there he stands by himself, since even those doctrines which he held in common with his predecessors he held after a fashion widely different as to both grounds and results. The doctrine of common sense, in particular, he set in a new light, rescued from misapprehension, and showed, o-n the testimony of every school of thought, to be one of the most widely recognized of philosophic tenets. In Reid he- found a philosopher to whom by many ties of intellectual affinity he was bound, and who seemed to him to have so unskilfully used the right clue to a solution of the problems 6 See Lectures on Logic, vols. iii. and iv., and Appendices, iv. 229-474; also
Discussions 1 17-173, 646-706.