Dispositional Properties

1. Hume: His Realist Sympathies and Reductionist Convictions

HUME: HIS REALIST SYMPATHIES AND REDUCTIONIST CONVICTIONS I David Hume's philosophy is sometimes an arena for the competing realist and reductionist theories of dispositional properties . He alternately supports the principal elements of both views. In the first portion of this chapter, I shall summarize the details of that section of A Treatise of Human Nature where Hume gives the details of his theory of abstract ideas and endorses the realist theory of powers. Hume believes that talk about abstract ideas is simplified talk about the fact that men think with determinate ideas which represent other ideas that can be brought to conscious reflection. "Can" in this instance is thought to mean that human beings have real powers for bringing the represented ideas to thought. The first section of my chapter is thus primarily a review of the difficulties which forced Hume to ground his theory of abstract ideas in a realist theory of powers. The effect of the discussion is to sharpen our understanding of what is important to a realist theory, and to prepare for the second section of the chapter, where a five- and ultimately, a four-factor account of dispositions is laid down. I make no claim that Hume is an historical witness to the realist theory as I shall develop it in this second section. Hume's discussion of powers is suggestive, but there are no arguments in Hume to convince us that powers are real. The DISPOSITIONAL PROPERTIES arguments which I shall propose sometimes begin with a reference to what Hume has said, but they never depend upon his authority for their truth. Moreover, though Hume's discussion of abstract ideas taken very literally could only justify the claim that a realist theory covers mental dispositions , I intend that it should also cover the dispositions of physical objects. The last portion of this chapter takes up the skeptical criticisms which Hume sometimes directs at the idea of real powers. I shall argue that these criticisms are mistaken, and that we can prove this by showing how they entail unacceptable consequences. la. Hume's own account: 1] His realist theory of powers; (a) Abstract ideas are determinate ideas representing other ideas; (b) Ideas represented in thought by another idea are held in power. Hume sets the problem of abstract ideas in this way: A very material question has been started concerning abstract or general ideas, whether they be general or particular in the mind's conception of them. A great philosopher has disputed the received opinion in this particular, and has asserted, that all general ideas are nothing but particular ones annexed to a certain term, which gives them a more extensive signification, and makes them recall upon occasion other individuals, which are similar to them. As I look upon this to be one of the greatest and most valuable discoveries that has been made of late years in the republic of letters, I shall here endeavour to confirm it by some arguments, which I hope will put it beyond all doubt and controversy .1 This is Berkeley's suggestion, and Hume is elated by it, because Berkeley affords him an easy solution to a considerable problem. Hume: Sympathies and Convictions 19 The problem has its origins in Hume's dogmatic assertion that impressions are precisely determinate in their quantity and quality, and that ideas are exact copies of impressions .2 These suppositions could make it difficult for Hume to explain the fluency of our thought. Imagine, for example, that a claim is made about triangles in general. In order to determine whether or not this claim is true, it should be necessary for us to run through a series of ideas having triangles of different shapes and sizes for their objects. But this could be tedious and encumbering. The procedure would be much simpler if there were a generic idea of triangularity for us to examine. (I am assuming, as Hume does, that geometric proofs are synthetic and depend upon imagined constructions, that our ideas are discrete images, and that thought is a stringing together of a series of images.) Though he is aware of the conveniences that generic ideas would afford, Hume wastes no time mourning for ideas which he thinks we do not have. There would be no point in this for he believes that thought is in no way disabled because of having ideas which are determinate in every...