J. J. C. Smart's advocacy of utilitarianism has been perhaps the most influential since Henry Sidgwick's nearly a century earlier. Nevertheless, there have been some significant developments since Smart's work, outlined here.

Fundamental to Smart's approach is his thesis that there can be no proof of ultimate normative moral principles. In this respect, ultimate normative principles, Smart thinks, are unlike many other kinds of claims. For example, some claims are true because of the definitions of the terms in them ("Bachelors are unmarried"). And, setting aside worries about induction, we observe that some claims are proven false by empirical investigation ("Drinking caffeinated coffee makes you sleepy"), and that other claims are confirmable by empirical investigation ("sugar dissolves in boiling water"). Ultimate normative principles, however, are different. They are not true by definition. They are neither refutable nor confirmable by purely empirical investigation. And ultimate normative principles...