Our simple ideas represent qualities; to think of a substance like a dog, however, we need to think of these qualities as inhering in or being unified by some underlying substratum (which he sometimes also calls ‘pure substance in general’). What is Locke’s attitude toward this substratum, and our knowledge of it?
(From II.xiii.19—Substance and accidents of little use in Philosophy) They who first ran into the notion of accidents, as a sort of real beings that needed something to inhere in, were forced to find out the word substance to support them.
Had the poor Indian philosopher (who imagined that the earth also wanted something to bear it up) but thought of this word substance, he needed not to have been at the trouble to find an elephant to support it, and a tortoise to support his elephant: the word substance would have done it effectually. And he that inquired might have taken it for as good an answer from an Indian philosopher—that substance, without knowing what it is, is that which supports the earth, as take it for a sufficient answer and good doctrine from our european philosophers—that substance, without knowing what it is, is that which supports accidents. So that of substance, we have no idea of what it is, but only a confused obscure one of what it does.
(From II.xiii.20—Sticking on and under-propping ) Whatever a learned man may do here, an intelligent american, who inquired into the nature of things, would scarce take it for a satisfactory account, if, desiring to learn our architecture, he should be told that a pillar is a thing supported by a basis, and a basis something that supported a pillar. Would he not think himself mocked, instead of taught, with such an account as this? … Were the latin words, inhaerentia and substantio, put into the plain english ones that answer them, and were called sticking on and under-propping, they would better discover to us the very great clearness there is in the doctrine of substance and accidents, and show of what use they are in deciding of questions in philosophy.
(From II.xxiii.23—Our obscure Idea of Substance in general ) So that if any one will examine himself concerning his notion of pure substance in general, he will find he has no other idea of it at all, but only a supposition of he knows not what support of such qualities which are capable of producing simple ideas in us; which qualities are commonly called accidents. If any one should be asked, what is the subject wherein colour or weight inheres, he would have nothing to say, but the solid extended parts; and if he were demanded, what is it that solidity and extension adhere in, he would not be in a much better case than the Indian before mentioned who, saying that the world was supported by a great elephant, was asked what the elephant rested on; to which his answer was—a great tortoise: but being again pressed to know what gave support to the broad-backed tortoise, replied—something, he knew not what.
- It’s vital to see that by ‘substance’ Locke means here ‘substratum’: that in which properties inhere. This notion is akin to Aristotle’s notion of prime matter. Why might one say that Locke has a love/hate relationship with substratum?