Dreaming, Perception, and Knowledge in Plato’s Theaetetus and Vasubandhu’s Twenty Verses

Abstract

Abstract This chapter examines the relevance of the philosophical use of dreaming for the examination of the thesis that knowledge is perception. It begins by studying the position attributed to Protagoras in Plato’s Theaetetus, according to which the perceptual experiences we have when dreaming count as knowledge. It argues that this position requires two different subjects in the two different contexts of cognition (dreaming and waking). It contends that Vasubandhu’s use of dreaming in the Twenty Verses—to show that perception without external objects is possible—can help make sense of Protagorean perception. It raises the problem that both positions struggle to align their metaphysics with the phenomenology of perception. With the help of dreaming, Vasubandhu can explain how transformation may yield perceptual knowledge (in the form of buddha-vision). No such transformation is possible for a Protagorean because the different subjects inhabiting different cognitive contexts are not causally related.