Adequate Ideas and Modest Scepticism in Hume's Metaphysics of Space

Abstract

In the Treatise of Human Nature, Hume argues that, because we have adequate ideas of the smallest parts of space, we can infer that space itself must conform to our representations of it. The paper examines two challenges to this argument based on Descartes's and Locke's treatments of adequate ideas, ideas that fully capture the objects they represent. The first challenge, posed by Arnauld in his Objections to the Meditations, asks how we can know that an idea is adequate. The second challenge, implicit in Locke's Essay, asks how an empiricist can characterize an idea as inadequate, as both picking out an object and yet failing to capture it fully. In showing how Hume responds to these challenges, his theory of perceptual representation is explained and his treatment of space is related to his scepticism. His conclusion is shown not to be a characterization of space as it exists wholly apart from our powers of conception. Instead, in an adumbration of Kant, his claim is restricted to space as it appears to us.Part 2 of Book 1 of Hume's Treatise, "Of the ideas of space and time", is the least discussed portion of his investigation of the understanding. Those interpreters who do address it usually focus on how Hume fits into the early modern debate over the ontological status of space and time and such subsidiary topics as the extent of their divisibility, the possibility of a vacuum, and the relation of parts to wholes. 1 In what follows, I focus instead on one way that Hume's discussion in this Part sets the stage for his later investigation of scepticism, especially in Part 4 of Book 1 of the Treatise, "Of the sceptical and other systems of philosophy". 2 Hume himself signals the con-1 See, for example, Broad 1961; Fogelin1988; Holden 2004; Jacquette 1996; and Raynor 1980. An exception to this trend is Baxter 2009. Baxter there relates Hume's treatment of space and time to different possible interpretations of Pyrrhonian scepticism, and thus he shares my goal of recognizing the links between Parts 2 and 4 of Book 1 of the Treatise. Baxter's paper was published only as I undertook final revisions of my essay. Though our conclusions are complementary, and I rely on one of his claims to clarify my point in § 6 of what follows, my argument was developed independently of his. 2 Hume's footnotes establish seven direct links between Parts 2 and 4 of Book 1. First, the discussion of the two different ways we can conceive of external objects at T 1.2.6 points us forward to T 1.4.2 (T 1.2.6.9n14; SBN 68n). Second, at T 1.4.2.2n34; SBN 188n, in specifying the explanandum for his account of the belief in the independent existence of objects, Hume refers us back to T 1.2.6. Third, Hume appeals to his treatment of the "fiction" of a perfect geometric standard of equality (T 1.2.4.24; SBN 47 f.) in his first explanation of our belief in the continued existence of sensory objects Brought to you by |

Hume's Dual Criteria for Memory

“…Scholars have argued that membership in a revival set is not subjective or arbitrary. The resemblance that fixes the revival set for ‘lemon’ is not just whatever resemblance happens to induce my mind to attach ‘lemon’ to an object; I would be mistaken about what ‘lemon’ signifies, for instance, if I understood its revival set to include limes or to exclude abnormal lemons (e.g., Ainslie, , 50; Cottrell, , 58). Even then, the requirement that revival‐set membership be objective or public still leaves membership indeterminate, as there can be multiple, equally objective ways of specifying the resemblance that fixes a set's membership.…”

Hume's Unified Theory of Mental Representation

“…Hume's point here is, in effect, that while we are capable of forming ever complex mathematical ideas via forming ever more complex customs for associating ideas together, the limits on our ability to form ever smaller images of objects constrain our ability to think of objects that correspond to these ever smaller numbers. For an excellent discussion of these issues, see Ainslie (2010). 46 This is true, even in the case of merely relative ideas, because even there the merely relative idea only acquires determinate truth conditions insofar as it relates the thing so represented to other things that we can form positive ideas of.…”

“…Hume's point here is, in effect, that while we are capable of forming ever complex mathematical ideas via forming ever more complex customs for associating ideas together, the limits on our ability to form ever smaller images of objects constrain our ability to think of objects that correspond to these ever smaller numbers. For an excellent discussion of these issues, see Ainslie ().…”

Hume, Empiricism and the Generality of Thought

“…10To much the same effect, Ainsley (2010) speaks of “image contents” and of “particular perceptions.” Hume’s designation “particular perceptions” is strictly correct, but like “idea,” “perception” too readily connotes “perception of” something else which is perceived. Hence my use of the deliberately awkward phrase ‘idea-object’.…”