15 - Humean Supervenience debugged  pp. 224-247


By David Lewis

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Years ago, I wrote that much of my work could be seen in hindsight as a campaign on behalf of “Humean Supervenience”: the thesis that the whole truth about a world like ours supervens on the spatiotemporal distribution of local qualities (1986, pp. ix-xvi). I thought this campaign had been mostly successful. Despite some unfinished business with causation, especially the problem presented in Menzies (1989), I think so still. But I wrote that “There is one big bad bug: chance. It is here, and here alone, that I fear defeat” (1986, p. xiv). I think I can say at last how to beat the bug. But first I'll have to take a lot of time reviewing old ground. I'll reintroduce Humean Supervenience, with some afterthoughts. I'll say what a Humean analysis of chance might look like. I'll say why Humean analyses of chance are in bad trouble, and why unHumean analyses are not an acceptable refuge. I'll give the beginning of a solution to the problem that plagues Humean analyses, and I'll say why that beginning is not good enough. And then I'll come at last to the good news: thanks to a suggestion by Michael Thau, I think I know how to complete the solution. The resulting rescue of Humean chance won't give us all we might wish, but I think it gives us enough.

So the key idea in this paper is Thau's. I thank him for kindly permitting me to use it here in my own way. But it can be used in other ways as well. Thau himself has not joined my campaign on behalf of Humean Supervenience.