A Treatise of Human Nature · David Hume
GENERAL INTRODUCTION TO VOL. I.
According to Locke’s account they are relations, and thus inventions of the mind. 110. To know what space itself is, ‘we are sent to our senses’ of sight and touch. It is ‘as needless to go to prove that men perceive by their sight a distance between bodies of different colours, or between the parts of the same body, as that they see colours themselves; nor is it less obvious that they can do so in the dark by feeling and touch.’ (Book II. chap. xiii. sec. 2.) Space being thus explained by reference to distance, and distance _between bodies_, it might be supposed that distance and body were simpler ideas. In the next paragraph, however, distance is itself explained to be a mode of space. It is ‘space considered barely in length between any two beings,’ and is distinguished _(a)_ from ‘capacity’ or ‘space considered in length, breadth, and thickness;’ _(b)_ from ‘figure, which is nothing but the relation which the parts of the termination of extension, or circumscribed space, have among themselves;’ _(c)_ from ‘place, which is the relation of distance between anything and any two or more points which are considered as keeping the same distance one with another, and so as at rest.’
It is then shown at large (Book II. chap. xiii. sec. 11), as against the Cartesians, that extension, which is ‘space in whatsoever manner considered,’ is a ‘distinct idea from body.’ The ground of the distinction plainly lies in the greater complexity of the idea of body. Throughout the definition just given ‘space’ is presupposed as the simpler idea of which capacity, figure, and place are severally modifications; and these again, as ‘primary qualities,’ though with a slight difference of designation, [1] are not only all declared inseparable from body, but are involved in it under a further modification as ‘_qualities of its solid parts_’ _i.e._, of parts so related to each other that each will change its place sooner than admit another into it. (Book II. chap. iv. sec. 2, and chap. viii. sec. 23.) Yet, though body is thus a complex of relations--all, according to Locke’s doctrine of relation, inventions of the mind--and though it must be proportionately remote from the simple idea which ‘comes first into the mind,’ yet, on the other hand, it is in body, as an object previously given, that these relations are said to be found, and found by the senses. (Book II. chap. xiii. secs. 2, 27.) [2] [1] In the enumeration of primary qualities, ‘capacity’ is represented by ‘bulk,’ ‘place’ by ‘situation.’
This is just such a contradiction as it would be to put to-day before yesterday. _We_ may escape it by the consideration that in the case before us it is not a succession of sensations in time that we have to do with at all; that ‘the real’ is an intellectual order, or mind, in which every element, being correlative to every other, at once presupposes and is presupposed by every other; but that this order communicates itself to us piecemeal, in a process of which the first condition on our part is the conception that there _is_ an order, or something related to something else; and that thus the conception of qualified substance, which in its definite articulation is the end of all our knowledge, is yet in another form, that may be called indifferently either abstract or confused, [2] its beginning. This way of escape, however, was not open to Locke, because with him it was the condition of reality in the idea of the body and its qualities that they should be ‘actually present sensations.’ The priority then of body to the relations of extension, distance, &c., as of that in which these relations are found, must, if body and extension are to be more than nominal essences, be a priority of sensations in time. But, on the other hand, the priority of the idea of space to the ideas of its several modes, and of these again to the idea of body, as of the simpler to the more complex, must no less than the other, if the ideas in question are to be real, be one in time. Locke’s contradiction, then, is that of supposing that of two sensations each is actually present, of two impacts on the sensitive tablet each is actually made, before the other.
Nor, however we might re-write his account of the relations of space as ‘found in bodies,’ could we avoid speaking of them as relations of some sort; and if relations, then derived from the ‘mind’s carrying its view from one thing to another,’ and not ‘actually present sensations.’ We shall not, then, be surprised to find Locke tending to the other alternative, and gradually forgetting his assertion that ‘a circle or a square are the same whether in idea or in existence,’ and his elaborate maintenance of the ‘real existence’ of a vacuum, _i.e._, extension without body. (Book II. chap. xiii. secs. 21 and the following, and xvii. 4.) In the Fourth Book it is body alone that has real existence, an existence revealed by actually present sensation, while all mathematical ideas, the ideas of the circle and the square, have ‘barely an ideal existence’ (Book IV. chap. iv. sec. 6); and this means nothing else than the reduction of the primary qualities of body to a nominal essence. Our ideas of them are general (Book IV. chap. iii. sec. 24), or merely in the mind. ‘There is no individual parcel of matter, to which any of these qualities are so annexed as to be essential to it or inseparable from it.’
(Book III. chap. vi. sec. 6.) How should there be, when the ‘individual parcel’ means that which copies itself by impact in the present sensation, while the qualities in question are relations which cannot be so copied? Yet, except as attaching to such a parcel, they have no ‘real existence;’ and, conversely, the ‘body,’ from which they _are_ inseparable, not being an individual parcel of matter in the above sense, must itself be unreal and belong merely to the mind. The ‘body’ which is real has for us no qualities, and that reference to it of the ‘actually present sensation’ by which such sensation is distinguished from other feeling, is a reference to something of which nothing can be said. It is a reference which cannot be stated in any proposition _really_ true; and the difference which it constitutes between ‘bare vision’ and the feeling to which reality corresponds, must be either itself unreal or unintelligible. Summary view of Locke’s difficulties in regard to the real.
113. We have now pursued the antithesis between reality and the work of the mind along all the lines which Locke indicates, and find that it everywhere eludes us. The distinction, which only appeared incidentally in the doctrine of substance, between ‘the being and the idea thereof--between substance as ‘found’ and substance as that which ‘we accustom ourselves to suppose’--becomes definite and explicit as that between real and nominal essence, but it does so only that the essence, which is merely real, may disappear. Whether we suppose it the quality of a mere sensation, as such, or of mere body, as such, we find that we are unawares defining it by relations which are themselves the work of the mind, and that after abstraction of these nothing remains to give the antithesis to the work of the mind any meaning. Meanwhile the attitude of thought, when it has cleared the antithesis of disguise, but has not yet found that each of the opposites derives itself from thought as much as the other, is so awkward and painful that an instinctive reluctance to make the clearance is not to be wondered at.
Over against the world of knowledge, which is the work of the mind, stands a real world of which we can say nothing but that it is there, that it makes us aware of its presence in every sensation, while our interpretation of what it is, the system of relations which we read into it, is our own invention. The interpretation is not even to be called a shadow, for a shadow, however dim, still reflects the reality; it is an arbitrary fiction, and a fiction of which the possibility is as unaccountable as the inducement to make it. It is commonly presented as consisting in abstraction from the concrete. But the concrete, just so far as concrete, _i.e._, a complex world of relations, cannot be the real if the separation of the real from the work of the mind is to be maintained. It must itself be the work of the compounding mind, which must be supposed again in ‘abstraction’ to decompose what it has previously compounded. Now, it is of the essence of the doctrine in question that it denies all power of origination to the mind except in the way of compounding and abstracting given impressions. Its supposition is, that whatever precedes the work of composition and abstraction must be real [1] because the mind passively receives it: a supposition which, if the mind could originate, would not hold. How, then, does it come to pass that a ‘nominal essence,’ consisting of definite qualities, is constructed by a mind, which originates nothing, out of a ‘real’ matter, which, apart from such construction, has no qualities at all? And why, granted the construction, should the mind in ‘abstraction’ go through the Penelopean exercise of perpetually unweaving the web which it has just woven?
115. In the Fourth Book of the Essay the same ground has to be thrice traversed under the several titles of ‘knowledge,’ ‘truth,’ and ‘propositions.’ Knowledge being the perception of agreement or disagreement between ideas, the proposition is the putting together or separation of words, as the signs of ideas, in affirmative or negative sentences (Book IV. chap. v. sec. 5), and truth--the expression of certainty [1]--consists in the correspondence between the conjunction or separation of the signs and the agreement or disagreement of the ideas. (Book IV. chap. v. sec. 2.) Thus, the question between the real and the mental affects all these. Does this or that perception of agreement between ideas represent an agreement in real existence? Is its certainty a real certainty? Does such or such a proposition, being a correct expression of an agreement between ideas, also through this express an agreement between things? Is its truth real, or merely verbal? [1] All knowledge is certain according to Locke (Cf. IV. chap. vi. sec. 13, ‘certainty is requisite to knowledge’), though the knowledge must be expressed before the term ‘certainty’ is naturally applied to it. (Book IV. chap. vi. sec. 3.) ‘Certainty of knowledge’ is thus a pleonastic phrase, which only seems not to be so because we conceive knowledge to have a relation to things which Locke’s definition denies it, and by ‘certainty,’ in distinction from this, understand its relation to the subject.
‘Certainty of truth’ is, in like manner, a pleonastic phrase, there being no difference between the definition of it (Book IV. chap. vi. sec. 3) and that of ‘truth’ simply, given in Book IV. chap. V. sec. 2. The knowledge expressed by a proposition, though certain, may not be real ... 116. To answer these questions, according to Locke, we must consider whether the knowledge, or the proposition which expresses it, concerns substances, _i.e._, ‘the co-existence of ideas in nature,’ on the one hand; or, on the other, either the properties of a mathematical figure or ‘moral ideas.’ If it is of the latter sort, the agreement of the ideas in the mind is itself their agreement in reality, since the ideas themselves are archetypes. (Book IV. chap. iv. secs. 6, 7.) It is only when the ideas are ectypes, as is the case when the proposition concerns substances, that the doubt arises whether the agreement between them represents an agreement in reality. The distinction made here virtually corresponds to that which appears in the chapters on the reality and adequacy of ideas in the Second Book, and again in those on ‘names’ in the Third. There the ‘complex ideas of modes and relation’ are pronounced necessarily real adequate and true, because, ‘being themselves archetypes, they cannot differ from their archetypes.’ (Book II. chap. XXX. sec. 4.) [1] With them are contrasted simple ideas and complex ideas of substances, which are alike ectypes, but with this difference from each other, that the simple ideas cannot but be faithful copies of their archetypes, while the ideas of substances cannot but be otherwise. (Book II. chap. xxxi. secs. 2, 11, &c.) Thus, ‘the names of simple ideas and substances, with the abstract ideas in the mind which they immediately signify, intimate also some real existence, from which was derived their original pattern. But the names of mixed modes terminate in the idea that is in the mind.’ (Book III. chap. iv. sec. 2.) ‘The names of simple ideas and modes,’ it is added, ‘signify always the real as well as nominal essence of their species’--a statement which, if it is to express Locke’s doctrine strictly, must be confined to names of simple ideas, while in respect of modes it should run, that ‘the nominal essence which the names of these signify is itself the real.’
(Book II. chap, xxxii. sec. 4.) Thus, what is said of the ‘simple idea’ in the Second and Third Books, is in the Fourth transferred to one form of knowledge concerning substances, to that, namely, which consists in ‘particular experiment and observation,’ and is expressed in singular propositions, such as ‘this is yellow,’ ‘this gold is now solved in aqua regia.’ Such knowledge cannot but be real, the proposition which expresses it cannot but have _real_ certainty, because it is the effect of a ‘body actually operating upon us’ (Book IV. chap. xi. sec. 1), just as the simple idea is an ectype directly made by an archetype. It is otherwise with complex ideas of substances and with general knowledge or propositions about them. A group of ideas, each of which, when first produced by a ‘body,’ has been real, when retained in the mind as representing the body, becomes unreal.
The complex idea of gold is only a nominal essence or the signification of a name; the qualities which compose it are merely ideas in the mind, and that general truth which consists in a correct statement of the relation between one of them and another or the whole--_e.g._, ‘gold is soluble in aqua regia’--holds merely for the mind; [2] but it is not therefore to be classed with those other mental truths, which constitute mathematical and moral knowledge, and which, just because ‘merely ideal,’ are therefore real. Its merely mental character renders it in Locke’s language a ‘trifling proposition,’ but does not therefore save it from being _really_ untrue. It is a ‘trifling proposition,’ for, unless solubility in aqua regia is included in the complex idea which the sound ‘gold’ stands for, the proposition which asserts it of gold is not certain, not a truth at all. If it is so included, then the proposition is but ‘playing with sounds.’ It may serve to remind an opponent of a definition which he has made but is forgetting, but ‘carries no knowledge with it but of the signification of a word, however certain it be.’ (Book IV. chap. viii. secs.
5 & 9.) Yet there is a real gold, outside the mind, of which the complex idea of gold in the mind must needs try to be a copy, though the conditions of real existence are such that no ‘complex idea in the mind’ can possibly be a copy of it. Thus the verbal truth, which general propositions concerning substances express, is under a perpetual doom of being really untrue. The exemption of mathematical and moral knowledge from this doom remains an unexplained mercy. Because merely mental, such knowledge is real--there being no reality for it to _mis_represent--and yet not trifling. The proposition that ‘the external angle of all triangles is bigger than either of the opposite internal angles,’ has that general certainty which is never to be found but in our ideas, yet ‘conveys instructive real knowledge,’ the predicate being ‘a necessary consequence of precise complex idea’ which forms the subject, yet ‘not contained in it.’ (Book IV. chap. viii. sec. 8.) [3] The same might be said apparently, according to Locke’s judgment (though he is not so explicit about this), of a proposition in morals, such as ‘God is to be feared and obeyed by man.’
(Book IV. chap. xi. sec. 13.) [4] But how are such propositions, at once abstract and real, general and instructive, to be accounted for? There is no ‘workmanship of the mind’ recognised by Locke but that which consists in compounding and abstracting (_i.e._, separating) ideas of which ‘it cannot originate one.’ The ‘abstract ideas’ of mathematics, the ‘mixed modes’ of morals, just as much as the ideas of substances, must be derived by such mental artifice from a material given in simple feeling, and ‘real’ because so given. Yet, while this derivation renders ideas of substances unreal in contrast with their real ‘originals,’ and general propositions about them ‘trifling,’ because, while ‘intimating an existence,’ they tell nothing about it, on the other hand it actually constitutes the reality of moral and mathematical ideas. Their relation to an original disappears; they are themselves archetypes, from which the mind, by its own act, can elicit other ideas not already involved in the meaning of their names. But this can only mean that the mind has some other function than that of uniting what it has ‘found’ in separation, and separating again what it has thus united--that it can itself originate. [1] See above, paragraph 25. [2] Book IV. chap. xi. sec. 13, xii. 9, &c. [3] Just as according to Kant such a proposition expresses a judgment ‘synthetical,’ yet ‘á-priori.’
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.
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.
Text from Project Gutenberg, public domain in the United States.