Modal epistemology made concrete

Many philosophers since Hume have accepted that imagining/conceiving a scenario is our prime guide to knowing its possibility. Stephen Yablo provided a more systematic criterion: one is justified in judging that p is possible if one can imagine a world which one takes to verify p. I defend a version of Yablo\u2019s criterion against van Inwagen\u2019s moderate modal scepticism. Van Inwagen\u2019s key argument is that we cannot satisfy Yablo\u2019s criterion because we are not in a position to spell out far-fetched possible scenarios in relevant detail. Van Inwagen\u2019s argument can be applied to the use of conceivability for everyday possibility claims, leaving us with the spectre of pervasive modal scepticism. In order to answer the sceptical threat, I combine van Inwagen\u2019s main example with general considerations about the nature of metaphysical modality to motivate a version of Yablo\u2019s criterion and show that it does not lead to scepticism. One structural condition of p being metaphysically possible is that it coheres with a complete reality. This condition gives rise to Yablo\u2019s criterion. However, for the criterion to be of any avail, we have to disregard details we are not in a position to specify. To account for our practice of doing so, I use Yablo\u2019s distinction between imagining a world as determinate and imagining it determinately. I present a condition when we may simply disregard details as determinate. The condition results from integrating analogical reasoning into the conceivability test