"Let us consider the concept of what might be called an "intellectual requirement." We may assume that every person is subject to a purely intellectual requirement—that of trying his best to bring it about that, for every proposition h that he considers, he accepts h if and only if h is true. One might say that this is the person's responsibility or duty qua intellectual being. (But as a requirement it is only a prima facie duty; it may be, and usually is, overridden by others, nonintellectual requirements, and it may be fulfilled more or less adequately.) One way, then, of re-expressing the locution "p is more reasonable than q for S at t" is to say this: "S is so situated at t that his intellectual requirement, his responsibility as an intellectual being, is better fulfilled by p than by q.""