Refutation, Deduction and The Demarcation of Philosophy from Sophistry

Abstract

This dissertation argues that Plato’s and Aristotle’s conceptions of genuine philosophical

argumentation were significantly shaped by their attempts to distance their own methods

from the argumentative practices of the Eristic sophists. The Eristics characteristically

employed short question-and-answer refutational arguments in which a questioner deduced a

conclusion based on an answerer’s commitments that contradicted one of the answerer’s

central philosophical positions, but did so in ways that we would now regard as fallacious. I

begin by showing that the Eristics’ refutations presented a significant challenge to Plato and

Aristotle not only because they derived contradictions based on important Platonic and

Aristotelian commitments, but also because the Eristics’ primary aim in offering these

refutations was to establish controversial doctrines that were immune to the contradictions

that they derived. In the remaining chapters I argue that Plato originally developed his

conception of a genuine contradiction in explicit contrast to the contradictions produced in

Eristic refutations and that Aristotle developed his conception of a deduction in direct

opposition to the ways in which Eristics deduced contradictory conclusions in their

refutations. Plato made it a necessary condition for a refutation that the contradiction it

produces satisfy conditions that clearly demarcate genuine contradictions from the merely

apparent ones that the Eristics produced. Aristotle then accepted and strengthened Plato’s

conception of true refutation by making it a necessary condition for a refutation that its

conclusion is deduced in accordance with a set of requirements that clearly exclude Eristic

ways of deducing from the class of genuine deductions. These logical innovations provided

both philosophers with the tools necessary to diagnose sophistical refutations as fallacies, and

thereby to resist the unpalatable doctrines the Eristics advanced through their arguments. On

the account I offer, it was in large part through their efforts to demarcate their argumentation

from that of these opponents that Plato laid the groundwork for, and Aristotle brought to

completion, the first system of logic in Western philosophy.