In this article I present a possible solution for the classic problem of the apparent incompatibility between Mill's Greatest Happiness Principle and his Principle of Liberty arguing that in the other-regarding sphere the judgments of experience and knowledge accumulated through history have moral and legal force, whilst in the self-regarding sphere the judgments of the experienced people only have prudential value and the reason for this is the idea according to which each of us is a better judge than anyone else to decide what causes us pain and which kind of pleasure we prefer (the so-called epistemological argument). Considering that the Greatest Happiness Principle is nothing but the aggregate of each person's happiness, given the epistemological claim we conclude that, by leaving people free even to cause harm to themselves, we still would be maximizing happiness, so both principles (the Greatest Happiness Principle and the Principle of Liberty) could be compatible.
John Stuart Mill; Greatest Happiness Principle; Principle of Liberty