As a philosophy, utilitarianism argues that a desire for happiness lies at the heart of all moral considerations. Mill’s essay expanded on the philosophical ideas initially proposed by Bentham and specifically sought to respond to common criticisms or misunderstandings of utilitarianism.

Mill defines utilitarianism as a theory based on the principle that "actions are right in proportion as they tend to promote happiness, wrong as they tend to produce the reverse of happiness." Mill defines happiness as pleasure and the absence of pain.