 Much of the first book of the Prolegomena is concerned with the role of self-consciousness in apparently discrete episodes of experience in individual minds. But Green is also concerned with the role of self-consciousness in knowledge. For the most part, non-rational animals accept the way things appear to them—their doxastic impulses. If they reason, they select instrumental means to the satisfaction of their desires, but they do not reason about whether things are as they appear. They lack the capacity to distance themselves from their appearances, to assess the credentials of their doxastic impulses, and to assent to appearances for good reasons. Brutes may often have true appearances, but they are not epistemically responsible with respect to their appearances. On the assumption that knowledge requires something like epistemic responsibility, and not just true belief, Green argues that knowledge requires self-consciousness, inasmuch as epistemic responsibility presupposes self-consciousness. For epistemic responsibility requires a cognizer to be able to pose the question of whether she should assent to an appearance and to assess the reasons for assent by relating this appearance to other elements of her consciousness. Indeed, any extended piece of reasoning requires consciousness of different appearances as parts of a single system. For instance, I recognize and trust the results of previous deliberations as premises in my present deliberations. This requires a self that is conscious of and synthesizes a set of appearances. On this view, knowledge presupposes epistemic responsibility which presupposes self-consciousness (PE §§84, 120, 125). This link between knowledge and self-consciousness via epistemic responsibility is arguably the most important metaphysical claim for understanding Green’s ethical argument in the rest of the Prolegomena.