Black - against quidditism.pdf - Ted Sider

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Downloaded By: [New York University] At: 21:44 25 May 2010 90 Against Quidditism the underlying truths of fundamental physics constitute the higher level truths in the sense that any possible world which duplicates ours at the level of fundamental physics thereby duplicates ours at all levels, or, if you like, after putting the fundamental laws and processes in place, God didn't have to do any extra work to get the rest. 4 This world thus exemplifies a certain mathematical structure (perhaps something like a four-dimensional manifold with an assignment to its points of the various fundamental quantities of quantum field theory, or perhaps at a deeper level which we do not yet understand something very different from this, but still--I am assuming--a mathematical structure). But of course the world could have been different, with different fundamental laws concerning different fundamental quantities, and thus exemplifying a different structure. Perhaps (but only perhaps, for I am not sure this is coherent) the world could even have been chaotic, having no laws, or no laws apart from the geometry of its spacetime, and beyond that only certain randomly distributed qualities, as for example with a 'Democritean' world where every point of spacetime is either occupied or not occupied by a single ordoffproperty. Even such a world would exemplify a mathematical structure (say a manifold with a distinguished subset of its points). Or, though I don't think there are any immaterial spirits, I think there might have been, that is to say, there might have been minds whose nature did not supervene on the physics of the non-mental. But even such an immaterial mind would have had a nature, a physis, and with it a physics, and thus it would exemplify a mathematical structure. Since in the infinite riches of the mathematical universe posse is esse, whatever abstract structures the world might have exemplified already do exist there. However the world could have been, there is, in that mathematical universe, the structure that it would then have exemplified. 5 In our physicalist supervenience claim, can we narrow the supervenience base still further? In particular, do the laws have to be in there? Once God had established what happened where and when, could He take His sabbatical rest, letting the laws look after themselves? Does the whole of contingent truth supervene just on the history of occurrences at the microlevel? There are two ways in which one could think this might be. One way would be if one thinks of the ingredients of this history--the fundamental properties concerned in the fundamental events--as being, or as constituted by, propensities or powers, and then of the laws as being generated and explained by these powers. If mass is a fundamental property, and if to have mass m just is (inter alia) to acquire acceleration F/m under the influence of resultant force F, then in creating a pattern of massive particles in fields of force, God would ipso facto have established Newton's second law of motion. But on this view it is not really that the laws are supervening on the history of occurrences; rather the laws are an intrinsic and inseparable part of the ingredients of that history. This view of properties as powers has obvious attractions [23], [24], [5], but it also has a well-known difficulty, namely its reliance on a primitive notion of propensity or power which many 4 I am aware that some claim not to understand this notion of supervenience, and I concede that there is work to be done chiselling away at its best formulation, but it seems to me intuitively clear enough. Alas, as Lewis remarks in another context, any competent philosopher who does not understand something will take care not to understand anything else whereby it might be explained. Lewis himself discusses the formulation of supervenience claims in [10, pp. 14-17]. 5 This does, of course, rule out the view that the world might have had no structure at all, but that seems to me lightly ruled out.
Downloaded By: [New York University] At: 21:44 25 May 2010 Robert <strong>Black</strong> 91 find mysterious. For the minute, I want to set it aside in favour of a clearer, simpler and much more ambitious supervenience thesis, David Lewis's 'Humean supervenience' [11, pp. ix-xvi]. For a Humean, properties, at least fundamental properties as opposed to functionally defined, higher-level properties, are not powers. As Hume himself puts it in Book I, Part III, Section XII of the Treatise, 'there is nothing in any object, consider'd in itself, which can afford us a reason for drawing a conclusion beyond it'. Lewis follows Hume in denying that fundamental properties have, let alone consist of, essential causal powers [10, pp. 91,162-3]. On his view 'there isn't much to the intrinsic nature of a universal'. 6 Just about all there is to a Humean fundamental quality is its identity with itself and its distinctness from other qualities. A Humean fundamental quality is intrinsically inert and self-contained. And a Humean world consists ultimately of no more than a pattern of instantiation of these inert fundamental qualities. Of course these qualities need particulars to be instantiated in, and a modem Humean need not be committed to the puzzling doctrine that particulars are reducible to the qualities they instantiate or get entangled in eighteenth-century confusions about the notion of substance. But the basic particulars might be, for example, points of spacetime. Spatiotemporal points bear certain fiandamental relations to one another--geometrical relations. On Lewis's view, these geometrical relations are probably the only fundamental relations, all other fundamental qualities being monadic. So the world consists of a pattern of instantiation of fundamental qualities in a geometrically organised spatiotemporal arena. On Lewis's picture of the world, the world is indeed very like a picture: just as a picture consists of a two-dimensional surface bearing a pattern of colours, with the totality of facts about the picture supervening on the facts about which colours are instantiated at which points, so for Lewis the world is a four-dimensional manifold bearing a pattern of fundamental qualities, with the totality of facts about the world supervening on the facts about which qualities are instantiated at which points. Lewis's account of the form supervenience takes ([8, pp. 73-7] and [14, §3]) is well-known: the laws are the theorems of whatever deductive system with only true consequences strikes the best balance between simplicity and strength. 7 Anti-Humeans feel in their bones that this can't be right, that such 'laws' would be mere coincidences, unable to support counterfactuals or to underlie local causal processes, and that expecting 'laws' of this kind which have held in the past to continue to hold in the future reduces inductive reason to unthinking prejudice. But Humeans like Lewis, who have different (or perhaps no) nerves in their bones, can of course reply that the best-system analysis precisely gives the distinction between laws and coincidences, can be teamed up with a Humean analysis of counterfactuals, shows that causation isn't really local after all, and just makes clearer what we have known since 1739, that there is no 'solution to the problem of induction'. The argument ends up as a stand-offbetween conflicting intuitions, [10, p. 205] Throughout this paper I shall talk of 'properties' or 'qualities', rather than universals or tropes, but that indicates detachment from the issue of how these things are best conceptualised rather than adoption of any particular view. I imagine that everything I say about qualities could, mutatis mutandis, be said in terms of tropes, and probably mutato nihilo in terms of universals. See [9] and [10, pp. 63-69]. This needs modification if we are to admit probabilistic laws, but I shall not concern myself with that here.
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