[4] Cf. Book IV. chap. iii. sec. 18, and Book III. chap, xi. sec. 16.
Significance of this doctrine.
118. A genius of such native force as Locke’s could not be applied to philosophy without determining the lines of future speculation, even though to itself they remained obscure. He stumbles upon truths when he is not looking for them, and the inconsistencies or accidents of his system are its most valuable part. Thus, in a certain sense, he may claim the authorship at once of the popular empiricism of the modern world, and of its refutation. He fixed the prime article of its creed, that thought has nothing to do with the constitution of facts, but only with the representation of them by signs and the rehearsal to itself of what its signs have signified—in brief, that its function is merely the analytical judgment; yet his admissions about mathematical knowledge rendered inevitable the Kantian question, ‘How are synthetic judgments á-priori possible?’—which was to lead to the recognition of thought as constituting the objective world, and thus to get rid of the antithesis between thought and reality. In his separation of the datum of experience from the work of thought he was merely following the Syllogistic Logic, which really assigns no work to the thought, whose office it professes to magnify, but the analysis of given ideas. Taking the work as that Logic conceived it (and as it must be conceived if the separation is to be maintained) he showed—conclusively as against Scholasticism— the ‘trifling’ character of the necessary and universal truths with which it dealt. Experience, the manifestation of the real, regarded as a series of events which to us are sensations, can only yield propositions singular as the events, and having a truth like them contingent. By consequence, necessity and universality of connection can only be found in what the mind does for itself, without reference to reality, when it analyses the complex idea which it retains as the memorandum of its past single experiences; i.e., in a relation between ideas or propositions of which one explicitly includes the other. Upon this relation syllogistic reasoning rests, and, except so far as it may be of use for convicting an opponent (or oneself) of inconsistency, it has nothing to say against such nominalism as the above. Hence, with those followers of Locke who have been most faithful to their master, it has remained the standing rule to make the generality of a truth consist in its being analytical of the meaning of a name, and its necessity in its being included in one previously conceded. Yet if such were the true account of the generality and necessity of mathematical propositions, their truth according to Locke’s explicit statement would be ‘verbal and trifling,’ not, as it is, ‘real and instructive.’
Fatal to the notion that mathematical truths, though general, are got from experience:
119. The point of this, the most obvious, contradiction inherent in Locke’s empiricism, is more or less striking according to the fidelity with which the notion of matter-of-fact, or of the reality that is not of the mind, proper to that system, is adhered to. When the popular Logic derived from Locke has so far forgotten the pit whence it was digged as to hold that propositions of a certainty at once real and general can be derived from experience, and to speak without question of ‘general matters-of-fact’ in a sense which to Locke almost, to Hume altogether, would have been a contradiction in terms, it naturally finds no disturbance in regarding mathematical certainty as different not in kind, but only in degree, from that of any other ‘generalisation from experience.’ Not aware that the distinction of mathematical from empirical generality is the condition upon which, according to Locke, the former escapes condemnation as ‘trifling,’ it does not see any need for distinguishing the sources from which the two are derived, and hence goes on asserting against imaginary or insignificant opponents that mathematical truth is derived from ‘experience;’ which, if ‘experience’ be so changed from what Locke understood by it as to yield general propositions concerning matters-of-fact of other than analytical purport, no one need care to deny. That it can yield such propositions is, doubtless, the supposition of the physical sciences; nor, we must repeat, is it the correctness of this supposition that is in question, but the validity, upon its admission, of that antithesis between experience and the work of thought, which is the ‘be-all and end-all’ of the popular Logic.
… and to received views of natural science: but Locke not so clear about this.
120. Locke, as we have seen, after all the encroachments made unawares by thought within the limits of that experience which he opposes to it—or, to put it conversely, after all that he allows ‘nature’ to take without acknowledgment from ‘mind’—is still so far faithful to the opposition as to ‘suspect a science of nature to be impossible.’ This suspicion, which is but a hesitating expression of the doctrine that general propositions concerning substances are merely verbal, is the exact counterpart of the doctrine pronounced without hesitation that mathematical truths, being at once real and general, do not concern nature at all. Real knowledge concerning nature being given by single impressions of bodies at single times operating upon us, and by consequence being expressible only in singular propositions, any reality which general propositions state must belong merely to the mind, and a mind which can originate a reality other than nature’s cannot be a passive receptacle of natural impressions. Locke admits the real generality of mathematical truths, but does not face its consequences. Hume, seeing the difficulty, will not admit the real generality. The modern Logic, founded on Locke, believing in the possibility of propositions at once real and general concerning nature. does not see the difficulty at all. It reckons mathematical to be the same in kind with natural knowledge, each alike being real notwithstanding its generality; not aware that by so doing, instead of getting rid, as it fancies, of the originative function of thought in respect of mathematical knowledge, it only necessitates the supposition of its being originative in respect of the knowledge of nature as well.
Ambiguity as to real essence causes like ambiguity as to science of nature. Particular experiment cannot afford general knowledge.
121. It may find some excuse for itself in the hesitation with which Locke pronounces the impossibility of real generality in the knowledge of nature—an hesitation which necessarily results from the ambiguities, already noticed, in his doctrine of real and nominal essence. So far as the opposition between the nominal and real essences of substances is maintained in its absoluteness, as that between every possible collection of ideas on the one side, and something wholly apart from thought on the other, this impossibility follows of necessity. But so far as the notion is admitted of the nominal essence being in some way, however inadequately, representative of the real, there is an opening, however indefinite, for general propositions concerning the latter. On the one hand we have the express statement that ‘universal propositions, of whose truth and falsehood we can have certain knowledge, concern not existence’ (Book IV. chap. ix. sec. 1). They are founded only on the ‘relations and habitudes of abstract ideas’ (Book IV. chap xii. sec. 7); and since it is the proper operation of the mind in abstraction to consider an idea under no other existence but what it has in the understanding, they represent no knowledge of real existence at all (Book IV. chap. ix. sec. 1). Here Locke is consistently following his doctrine that the ‘particularity in time,’ of which abstraction is made when we consider ideas as in the understanding, is what specially distinguishes the real; which thus can only be represented by ‘actually present sensation.’ It properly results from this doctrine that the proposition representing particular experiment and observation is only true of real existence so long as the sensation, in which the experiment consists, continues present. Not only is the possibility excluded of such experiment yielding a certainty which shall be general as well as real, but the particular proposition itself can only be really true so far as the qualities, whose co-existence it asserts, are present sensations. The former of these limitations to real truth we find Locke generally recognising, and consequently suspecting a science of nature to be impossible; but the latter, which would be fatal to the supposition of there being a real nature at all, even when he carries furthest the reduction of reality to present feeling, he virtually ignores. On the other hand, there keeps appearing the notion that, inasmuch as the combination of ideas which make up the nominal essence of a substance is taken from a combination in nature or reality, whenever the connexion between any of these is necessary, it warrants a proposition universally true in virtue of the necessary connexion between the ideas, and really true in virtue of the ideas being taken from reality. According to this notion, though ‘the certainty of universal propositions concerning substances is very narrow and scanty,’ it is yet possible (Book IV. chap. vi. sec. 13). It is not recognised as involving that contradiction which it must involve if the antithesis between reality and ideas in the mind is absolutely adhered to. Nay, inasmuch as certain ideas of primary qualities, e.g. those of solidity and of the receiving or communicating motion upon impulse, are necessarily connected, it is supposed actually to exist (Book IV. chap iii. sec. 14). It is only because, as a matter of fact, our knowledge of the relation between secondary qualities and primary is so limited that it cannot be carried further. That they are related as effects and causes, it would seem, we know; and that the ‘causes work steadily, and effects constantly flow from them,’ we know also; but ‘their connexions and dependencies are not discoverable in our ideas’ (Book IV. chap. iii. sec. 29). That, if discoverable in our ideas, just because there discovered, the connexion would not be a real co-existence, Locke never expressly says. He does not so clearly articulate the antithesis between relations of ideas and matters of fact. If he had done so, he must also have excluded from real existence those abstract ideas of body which constitute the scanty knowledge of it that according to him we do possess (Book IV. chap. iii. sec. 24). He is more disposed to sigh for discoveries that would make physics capable of the same general certainty as mathematics, than to purge the former of those mathematical propositions—really true only because having no reference to reality—which to him formed the only scientific element in them.
What knowledge it can afford, according to Locke.