 In his Philosophical Investigations, Wittgenstein famously writes: “An ‘inner process’ stands in need of outward criteria” (580). Exactly what Wittgenstein meant by this remark is unclear, but one way in which it might be interpreted is as follows: in order to be justified in ascribing a “mental state” to some entity, there must be some true claims about the observable behavior of that entity that, (perhaps) together with other true claims about that entity (not themselves couched in “mentalistic” vocabulary), entail that the entity has the mental state in question. If no true claims about the observable behavior of the entity can play any role in the justification of the ascription of the mental state in question to the entity, then there are no grounds for attributing that kind of mental state to the entity.