Indiscriminability and the Sameness of Appearance

How exactly should the relation between a veridical perception and a corresponding hallucination be understood? I argue that the epistemic notion of 'indiscriminability', understood as a lack of evidence for the distinctness of things, is not suitable for defining this relation. Instead, we should say that a hallucination and a veridical perception involve the same phenomenal properties. This has further consequences for attempts to give necessary and sufficient conditions for the identity of phenomenal properties in terms of indiscriminability, and for considerations about the phenomenal sorites.