The Case for the Dependence of Logic on Ethics: From Charles Peirce to Today’s Philosophy of Logic

Over a century ago, Charles Peirce proposed that reasoning is a kind of conduct, and the logical good and bad are ultimately nothing but a specific application of the moral good and bad. This thesis constitutes a foundational claim in Peirce’s philosophical system and offers critical insights for contemporary philosophers reevaluating the nature of logic. This article attempts to reconstruct the justification for Peirce's thesis from two perspectives: (1) The subject matter of logic and (2) The problem of choice in theories of logic. Then, in response to two possible objections, I draw on Peirce’s ideas and contemporary resources in the philosophy of logic. As Peirce demonstrated and this article further reinforces, it is highly likely that logic is dependent on ethics–a science concerned with purposes and ideals–to establish and uphold its normative status in human thought.