Hume on knowledge of metaphysical modality

I outline Hume’s views about conceivability evidence. Then I critically scrutinize two threats to conceivability-based modal epistemology. Both arise from Hume’s criticism of claims to knowing necessary causal relationships: Firstly, a sceptical stance towards causal necessity may carry over to necessity claims in general. Secondly, since -according to a sceptical realist reading- Hume grants the eventuality of causal powers grounded in essential features of objects, conceivability-based claims to comprehensive metaphysical possibilities seem endangered. I argue that although normal conceivability-based claims are defeasible, they are prima facie vindicated.