 The distinction between sensory perception and judgmental acumen enables Austin to distinguish between central cases of illusion and central cases of delusion, and also to sketch explanations of what is going on in those cases that do not make appeal to sense-data. Austin takes the defender of (i) and (ii) to argue as follows. First, consider an illusion, for example a stick that looks bent but really isn’t. Such an illusion has two key features. First, it clearly involves a distinctive sensory experience. Second, the distinctive sensory experience that it involves is apt to give rise to an erroneous perceptual judgment, to the effect that the stick is bent. Now one way of explaining the erroneous perceptual judgment is to view it as dictated by the sensory experience—that is, to view it as accurately representing features presented in the experience: the bent-ness of that which is experienced. Since the stick is not in fact bent, and that which is experienced is bent, we have reason to claim that that which is experienced is not identical with the stick. What we experience is sense-data rather than a stick. Moreover, we might also consider more extreme cases in which we make erroneous perceptual judgments: cases of delusion or hallucination. For example, there is the case in which an alcoholic person judges that pink rats are visible, when in fact there are none. Now, given the proposed account of the case of illusion, that case cannot be distinguished from the case of delusion by appeal to the fact that, in the former, an environmental feature is experienced while, in the latter, there is no suitable environmental feature to be experienced. It therefore seems natural to treat the two cases as of the same basic type, and to offer the same type of explanation for both. Thus, one might be tempted to view the rat-delusion as having the following three features. First, it involves a distinctive sensory experience. Second, the distinctive sensory experience that it involves dictates an erroneous perceptual judgment to the effect that pink rats are visible. Third, that judgment is dictated because it accurately represents features present in the experience.