Year of Publication


Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation


Arts and Sciences



First Advisor

Dr. Eric Sanday


This dissertation is a study of the ontological foundations of true and false speech in Plato’s Sophist. Unlike most contemporary scholarship on the Sophist, my dissertation offers a wholistic account of the dialogue, demonstrating that the ontological theory of the “communing” of forms and the theory of true and false speech later in the dialogue entail one another.

As I interpret it, the account of true and false speech in the Sophist is primarily concerned with true and false speech about the forms. As Plato sees it, we can only make true statements about spatio-temporal beings if it is possible to make true statements about the forms. Statements about the forms, however, make claims about how forms “commune” with other forms, that is, how forms are intelligibly related to and participate in one another. If forms stand in determinate relations of participation to other forms, however, then forms, as the relata of these relations, must compose structured wholes. Yet if they compose structured wholes, there must be a higher order normative principle that explains their structure. This creates a regress problem. In order to ground the structure of spatio-temporal beings, forms must be the highest explanatory principles. The theory of the “communing” of forms, however, makes it seem as if the forms require further explanation.

This dissertation argues (1) that in the Sophist Plato solves the regress problem and (2) that, by doing so, he is able to ground true and false speech about the forms. I demonstrate that he solves the regress problem by differentiating a form’s nature from a form qua countable object. Then I show that this distinction between a form’s nature and a form qua countable object explains how true and false statements about the forms are possible.