  For instance, according to one widely held view, the perceptual judgements one makes when one is having a perfect hallucination can be justified and have the same justificatory status as the perceptual judgements one makes when one genuinely perceives the world. According to this view, there is a sense, then, in which the conclusion of the tempting line of argument that McDowell considers is true: when you genuinely perceive the world your epistemic grounds for making world-directed perceptual judgements are the same as, an hence no better than, those available to you when you have a subjectively indistinguishible hallucination. However, those who accept this claim may deny that this puts into jeopardy the common sense idea that when we do succeed in perceiving the world we usually do acquire non-inferential, world-directed, perceptual knowledge. For they may claim the epistemic difference between a veridical perception and hallucination is not to be explained by appealing to some difference in the justificatory status of the judgements that such experiences give rise to. The epistemic difference is, rather, to be explained by appealing to the fact that when one perceives the world some further conditions required for perceptual knowledge will usually be met.