Alex Worsnip

Many epistemologists call themselves ‘fallibilists’. But many philosophers of language hold that the meaning of epistemic usages of ‘possible’ ensures a close knowledge- possibility link : a subject’s utterance of ‘it’s possible that not-p’ is true only if the subject does not know that p. This seems to suggest that whatever the core insight behind fallibilism is, it can’t be that a subject could have knowledge which is, for them, possibly false. I argue that, on the contrary, subjects can have such possibly false knowledge. My ultimate aim, then, is to vindicate a very robust form of fallibilism. Uniquely, however, the account I offer does this while also allowing that concessive knowledge attributions – sentences of the form “I know that p, but it’s possible that not-p” – are not only infelicitous but actually false whenever uttered. The account predicts this result without conceding KPL. I argue that my account has the resources to explain some related cases for which the KPL account yields the wrong predictions. Taken as a whole, the linguistic data not only do not support the proposal that subjects cannot have possibly false knowledge, but indeed positively favor the proposal that they can.

We offer a new argument in favour of metanormative contextualism, the thesis that the semantic value of a normative ‘ought’ claim of the form ‘ S ought to Φ’ depends on the value of one or more parameters whose values vary in a way that is determined by the context of utterance. The debate over this contextualist thesis has centred on cases that involve ‘ought’ claims made in the face of uncertainty regarding certain descriptive facts. Contextualists, relativists, and invariantists all have plausible ways of explaining these cases, and one could reasonably judge the debate between these views to be a stalemate. We argue that this stalemate can be broken by shifting focus to a case that involves normative uncertainty rather than descriptive uncertainty. While relativist and invariantist rivals of contextualism can give plausible accounts of the descriptive uncertainty cases, only contextualism can provide a plausible account of the normative uncertainty case.