Utilitarianism

"It is indisputable that the being whose capacities of enjoyment are low, has the greatest chance of having them fully satisfied; and a highly endowed being will always feel that any happiness which he can look for, as the world is constituted, is imperfect. But he can learn to bear its imperfections, if they are at all bearable; and they will not make him envy the being who is indeed unconscious of the imperfections, but only because he feels not at all the good which those imperfections qualify.

It is better to be a human being dissatisfied than a pig satisfied; better to be Socrates dissatisfied than a fool satisfied. And if the fool, or the pig, is of a different opinion, it is only because they only know their own side of the question."
--- John Stuart Mill, Utilitarianism

John Stuart Mill's book Utilitarianism is one of the most influential and widely-read philosophical defenses of utilitarianism in ethics. The essay first appeared as a series of three articles published in Fraser's Magazine in 1861; the articles were collected and reprinted as a single book in 1863. It went through four editions during Mill's lifetime with minor additions and revisions.

Although Mill includes discussions of utilitarian ethical principles in other works such as On Liberty and The Subjection of Women, Utilitarianism contains Mill's only major discussion of the fundamental grounds for utilitarian ethical theory.