Characterizing hallucination epistemically

According to the epistemic theory of hallucination, the fundamental psychological nature of a hallucinatory experience is constituted by its being ‘introspectively indiscriminable’, in some sense, from a veridical experience of a corresponding type. How is the notion of introspective indiscriminability to which the epistemic theory appeals best construed? Following M. G. F. Martin, the standard assumption is that the notion should be construed in terms of negative epistemics: in particular, it is assumed that the notion should be explained in terms of the impossibility that a hallucinator might possess a certain type of knowledge on a certain basis. I argue that the standard assumption is mistaken. I argue that the relevant notion of introspective indiscriminability is better construed in terms of positive epistemics: in particular, I argue that the notion is better explained by reference to the fact that it would be rational for a hallucinator positively to make a certain type of judgement, were that judgement made on a certain basis.