EPISTEMOLOGY says that here and now there is a visual non-straight-looking sense-datum, and here and now there is a tactile straight-feeling sense-datum Aristotle, like the sense-datum theorists, deals with the inconsistent quartet by qualifying (1) and (2) But he does not so by altering the content of p The senses tell us about external realities and not about an alleged purely mental entity such as a sense-datum He solves his problems by focusing on Sense Wherever we have an apparent case of Sense saying that p, and Sense saying that not-p, we really have a case of one sense S1 saying that p, and another sense S2 saying that not-p Not all that the senses tell us is true, and if S1 and S2 tell us diVerent stories we can give reasons for making a choice between them It is an essential part of the Protagorean contention that where two judgements of sense conXict, there should be no reason for preferring the one to the other in regard of truth But someone might say that in the case of the conXict of tastes between healthy and sick, we are to prefer the report of the healthy, since this is the opinion of the majority The reply to this that Aristotle oVers Protagoras is that we cannot treat majority opinion as the criterion of truth If a worldwide epidemic broke out, those now called healthy might be outnumbered, and there would no longer be reason to accept as true their opinion that honey is sweet (Metaph C 1009a1–5) Aristotle can agree that the reason for preferring healthy perception to diseased perception must be something other than statistical But he counters the Protagorean conclusion by saying that everyone does in fact grade appearances and no one treats them as all equally trustworthy If you doze oV in Libya and dream you are in Athens, you not, on waking, set oV for the Athens theatre (Metaph C 1010b11) Aristotle oVers a number of criteria for ranking sense-appearances when it is necessary to choose between them, the most important of which is that a sense has priority when it is judging its proper object The proper object of each sense is deWned in the de Anima (2 418a12) as being that which cannot be perceived by another sense, and that about which it is impossible to be deceived: colour is the proper object of sight, sound of hearing, and Xavour of taste Aristotle’s Wrst point is clear enough: we cannot taste a colour, hear a Xavour, or see a sound But what is meant by saying that a sense cannot be deceived about its proper object? Aristotle is quick to explain that if I see something white, I can be mistaken about 162