A Second Copy Thesis in Hume?

A Second Copy Thesis in Hume? George S. Pappas The copy thesis which applies to simple ideas andimpressionsin Hume is well known; every simple idea is supposed to be a copy of, that is, to exactly resemble, some simple impression. Or very nearly so, at any rate, for there is the famous missing shade ofblue to take into account. There seems to be another copy thesis in Hume, however, and one on which Hume places a great deal ofweight. We find it expressed early on in the Treatise, incorporated into Hume's discussion of space and time. He says: Wherever ideas are adequate representations of objects, the relations, contradictions and agreements of the ideas are all applicable to the objects; and this we may in general observe to be the foundation of all human knowledge. But our ideas are adequate representations of the most minute parts of extension; and thro' whatever divisions and subdivisions we may suppose these parts to be arriv'd at, they can never become inferior to some ideas, which we form. The plain consequence is, that whatever appears impossible and contradictory upon the comparison of these ideas, must be really impossible and contradictory, without any farther FogeUn has recently described this as a "remarkable passage," one which is "a match for anything found in the writings of the rationalists."2 Perhaps it is such a match, perhaps not, but Fogelin is certainly right to regard this as a remarkable passage, at least for Hume. After all, Hume here seems to be endorsing some form of representationalism, a doctrine we typically do not associate with Hume's philosophy. Two important questions emerge from this passage:just what are these adequate ideas ofwhich Hume speaks; and, in what sense can it be true that they form the foundation ofall ofour knowledge? I believe that a correct answer to each of these questions has some strong imphcations for our understanding ofHume's philosophy. I. Humean Adequate Ideas So far as I can discover, the above-quoted passage is the Only place where Hume talks about adequate ideas. The only text which I have Volume XVII Number 1 51 GEORGE S. PAPPAS found which even suggests the same sentiments occurs in "Of the Passions" where Hume discusses ideas and truth (T 448-49), but no mention is made there of adequate ideas. So I think we have to concentrate on the passage from the Treatise in the attempt to understand what Hume is telling us. Hume seems to refer to adequacy as a feature ofindividual ideas, and also to groups or systems ofideas. The latter is suggested by his reference to relations, contradictions, and agreements between ideas, while the former is indicated by the first clause ofthe quoted passage, where Hume mentions adequacy but makes no reference to relations between ideas. Instead, adequacy in the relationsbetween ideas seems to be a consequence of adequacy of individual ideas. Moreover, that individual ideas are supposed to be adequate is made clear from the argument Hume immediately gives regarding the alleged infinite divisibility of space. He writes: I first take the least idea I can form ofa part ofextension, and beingcertainthatthereis nothingmoreminute than thisidea, I conclude, that whatever I discover by its means must be a real quality ofextension. (T 29) Hume's reasoning here can be interpreted in two different ways, but both rest on the adequacy of individual ideas. He might be read as saying that one starts with a least-sized idea, and infers that there are bits of extension which are the same size as the least-sized idea. The inference from the feature of the idea to the feature of the bit of extension rests on the claimed adequacy ofthe idea. The other reading of Hume's reasoning is that one starts with the least-sized idea and then infers that there is (a) a bit ofextended matter that small, and (b) that there is no smaller bit of extended matter. Ofthese two readings, I think the second is the right way to understand Hume here, for only it supports the argument's conclusion that space is not infinitely divisible.3 But notice that this second version ofHume...