Current philosophy of perception has its roots in the assumption of what is sometimes called "the Cartesian epistemological tradition". These assumptions are: (1) That to understand what knowledge is one must understand what justified belief is; (2) That the justification of a person S's belief in a contingent proposition is always at least partly constituted by S's perceptual judgments ("I see that this is red", "I hear that a dog is barking", "I smell (that)the house (is) burning", etc.); (3) That whenever S judges perceptually S has a sensory experience; (4) That S's perceptual judgment derives its warrant at least partly from propositions about the accompanying sensory experience; (5) That these sensory propositions are self-warranted - They do not derive all of their warrant from other propositions. (This interpretation is defended in Firth [1] and critiqued in Pastin [2].) Current philosophy of perception has its roots in these assumptions in that it has developed from a series of attempts to defend, elaborate, or criticize some of these assumptions, particularly, assumptions (3) to (5).