Aristotle, Menaechmus, and Circular Proof

Abstract

(a)The Regress: Knowledge, we like to suppose, is essentially a rational thing: if I claim to know something, I must be prepared to back up my claim by statingmy reasons for making it;and if my claim is to be upheld, my reasons must begood reasons. Now suppose I know that Q; and let my reasons be conjunctively contained in the proposition that R. Clearly, I mustbelievethat R (for R cannot give my reasons unless it has my assent);equally clearly, I mustknowthat R (for mere opinion is not nutritious enough to sustain the demanding body of knowledge). Thus if I know that Q, I know that R. But if I know that R, then I must have my reasons, R' for holding R; and, by the same argument, I mustknow that R'. And if R', then R”; and so on,ad infinitum