[81]. The reader who desires to study Kant’s doctrine in detail may begin by taking up Kant’s own Prolegomena to the Study of any future Metaphysic, which may be profitably consulted even by those who find the Critique of Pure Reason too diffuse and technical.[technical.] The latest and cheapest translation is that included in the Open Court Publishing Co.’s series of Philosophical Classics.
[82]. “Arbitrarily” because it is, as all recent psychology insists, the direction of our attention which determines what qualities shall be presented together, and thus become “associated.”
[83]. In Psychology this comes out in the rejection by the best recent writers of the whole associationist account of the process of perception, according to which the perception of a thing as a whole was taken to mean the actual presence in sensation of one of its qualities plus the reinstatement by association of the “ideas” of the others. For the modern doctrine of the perception of a whole, as distinct from the mere perception of its constituent parts, consult Stout, Analytic Psychology, bk. i. chap. 3, or Manual of Psychology,3 bk. i. chap. 3.
[84]. This is just as true of the so-called primary qualities of things as of any others. Thus the mass and again the kinetic energy of a conservative material system are properly names for the way in which the system will behave under determinate conditions, not of modes of behaviour which are necessarily actually exhibited throughout its existence. The laws of motion, again, are statements of the same hypothetical kind about the way in which, as we believe, particles move if certain conditions are fulfilled. The doctrine according to which all events in the physical world are actual motions, rests on no more than a metaphysical blunder of a peculiarly barbarous kind. Cf. Stallo, Concepts and Theories of Modern Physics, chaps. 10-12.
[85]. Thus, e.g., so fundamental a proposition in our current mechanical science as the “first law of motion” is avowedly a statement as to what would be the behaviour of things under a condition which, so far as we know, is never actually realised. On the thing as the “law of its states,” see Lotze, Metaphysic, I. 3. 32 ff. (Eng. trans., vol. i. p. 88 ff.), and L. T. Hobhouse, The Theory of Knowledge, pp. 545-557.
[86]. Mr. Hobhouse (op. cit., p. 541 ff.) thinks that the solution is simply that those qualities belong to one “substance,” which are apprehended together as occupying one space. As a working criterion of what we mean by one bodily thing, this account seems satisfactory, and has probably suggested itself spontaneously to most of us. But it leaves untouched the more fundamental question how the identification of a certain sight-space with a certain touch-space is effected, and what are the motives which lead to it. Mr. Hobhouse is content to take the identification as “given in adult perception,” but it seems to me to emerge from his own good account of the matter that it is the still more primitive apprehension of my own body as a felt unity upon which the synthesis between sight and touch spaces is based. If so, the ultimate source of the “unity of substance” must be sought deeper than Mr. Hobhouse is willing to go for it. And quaere, whether his account, if accepted as ultimate, would not lead to the identification of substance with space? For the difficulties which arise when you say the substance is the space and its filling of qualities, see Appearance and Reality, chap. 2, pp. 19, 20 (1st ed.).
[87]. Monadology, §§ 8-16, 57-62.
[88]. This is true even where we merely count a number of qualitatively equivalent units in order to ascertain their sum. It is their positive character of being qualitatively equivalent which makes it permissible in this case to take any one of them indifferently as first, any other as second, etc. Whenever you apply the numerical series to the arrangement in order of the qualitatively dissimilar, the nature of your material as related to the character of your special interest in it decides for you what you shall call first, second, third, etc.
[89]. As to the possibility of relations which are in this sense external to their terms, see B. Russell, The Philosophy of Leibniz, p. 130, and the articles by the same writer in Mind for January and July 1901.
[90]. See the elaborate discussion of the relational scheme implied in any assertion of difference in Royce, The World and the Individual, Second Series, lect 2.