  According to the phenomenal conception of evidence, only one's experiences can serve as evidence. According to Williamson's conception of evidence as knowledge, one's experiences are excluded from counting as evidence—at best, one's evidence includes whatever propositions about one's experiences that one knows. Even if one abandons the phenomenal conception of evidence, however, one might hold on to the idea that one's evidence includes one's experiences, inasmuch as one's experiences can and often do make some difference to what one is justified in believing, regardless of whether one forms beliefs about those experiences themselves. A view of evidence that is more liberal than either Williamson's or the phenomenal conception might thus take one's evidence to include both one's experiences and one's knowledge, on the grounds that the beliefs of a rational thinker will exhibit direct sensitivity both to what he knows and to the experiences that he undergoes. The question of whether one's experiences—as opposed to one's beliefs about one's experiences, or one's knowledge of one's experiences—can play a direct role in justifying beliefs about the external world is a much contested one in the philosophy of perception; it will not be pursued further here.