The idea that rhetoric might operate in epistemologically significant ways was first presented by Plato. This paper argues that the heart of Plato's conception of epistemic discourse is a recognition of the centrality of intrapersonal rhetoric. Through a careful study of Platonic writing, particularly the "Phaedrus," three principal elements of rhetorical theory are identified: rhetoric encompasses any form of address, spoken or written, on any subject; rhetoric is a separate discipline with its own subject matter, methods, and principles; and rhetoric can function only to the degree that it influences the soul. After discussing the "rhetoric is epistemic" doctrine of contemporary theorists, the paper draws on Plato's epistemology, based on his explicit statement that "the function of oratory is in fact to influence men's souls," and articulates the differences between the two points of view. The paper proposes a concept of rhetorical dialectic that avoids an "either/or" position and offers a unique way of explaining the generation of knowledge. Ten pages of end notes accompany the paper. (MAI)