 Suppose, for example, that the following sufficient condition of justified belief is offered: “If S senses redly at t and S believes at t that he is sensing redly, then S’s belief at t that he is sensing redly is justified”. This is not the kind of principle I seek; for, even if it is correct, it leaves unexplained why a person who senses redly and believes that he does, believes this justifiably. (1979: 106)