 In principle, you might get perceptual justification from a success state in the good case of vision or illusion, and get the same amount of perceptual justification from a non-success state in the bad case of hallucination (Lord forthcoming takes up a view with this structure regarding reasons for belief). We bracket that sort of approach here. It is more common to hold that you get no perceptual justification in the case of hallucination (e.g., Jackson 2011), or at least a lower degree or different kind of perceptual justification in the case of hallucination (e.g., Schellenberg 2013).