Igniting the Deontic Consequence Relation: Dilemmas, Trumping, and the Naturalistic Fallacy

Abstract

In this work, Kurt Holukoff examines three formal approaches to representing valid inferences in reasoning regarding obligation and its cognates: deontic logic. He argues that an appropriate formalization of deontic logic should take genuine moral dilemmas seriously, be capable of representing trumping-like reasoning, and not make the naturalistic fallacy valid as a matter of logic. The three systems he investigates are, the Standard Deontic logic, a Relevant Deontic logic, and Schotch and Jennings’ multiple moral accessibility relations Deontic logic. The Standard Deontic logic has seemingly insurmountable problems representing both fruitful reasoning from an inconsistent set of obligations and trumping-like reasoning. Moreover, the naturalistic fallacy is valid in the Standard Deontic logic. The Relevant deontic logic that the author examines is capable of representing fruitful reasoning from an inconsistent set of obligations and does not make valid the naturalistic fallacy. However, the author argues that the Relevant deontic logic needs some revisions in order to represent trumping-like reasoning. Likewise, the author finds that Schotch and Jennings’ Deontic logic is capable of representing fruitful reasoning from an inconsistent set of obligations. However, in order to represent trumping-like reasoning, revisions to Schotch and Jennings’ Deontic logic are apparently required. Similar revisions are seemingly required to block the naturalistic fallacy, which is otherwise valid in Schotch and Jennings’ original system.