- Philip Percival's 'On Realism about Chance' considers the metaphysical status of another modal2 notion, namely chance.
- Chance, as Percival conceives it, is a single-case (applying to individual events), temporally relative (liable to change over time), objective probability (existing independently of what anyone thinks about it) towards which our cognitive attitudes are normatively constrained.
- Percival construes the question of whether chance exists as the question of whether there are objectively true statements of the form 'the chance at time t of event E is r'.
- Famously, Lewis has advanced realism about chance but Percival takes issue with this assessment, arguing for scepticism about the kinds of reason one might give for realism about chance.
- One common reason for affirming realism about chance is that chance may be used to explain statistical phenomena or the warrantedness of certain credences. But, Percival argues, the notion of chance cannot perform this kind of explanatory role. Consequently, an inference to the best explanation of (e.g.) statistical phenomena cannot be employed to ground realism about chance.
- Another reason commonly offered for affirming realism about chance is that chance may be analysed in terms of non-chance. If chance is analysable then either chance supervenes3 (relatively) locally upon non-chance or chance supervenes4 globally upon non-chance. But however chance supervenes5, Percival argues, no extant analysis — including Lewis's 'best-system' analysis—succeeds.
- Percival concludes upon the sceptical reflection that there is little prospect of a correct analysis of chance being forthcoming in the future that vindicates realism about chance.
- Chance and Inference to the Best Explanation
- 1.1 Statistical Phenomena
- 1.2 Temporally Relative Warrant
- Analyses of Chance
- 2.1 Frequentist Analyses
- 2.2 Lewis’s “Best System” Analysis of Chance
- 2.3 The Problem of Fit
- 2.4 “Fit” as a Primitive?
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