Utilitarianism is one of the most powerful and persuasive approaches to normative ethics in the history of philosophy. Though not fully articulated until the 19th century, proto-utilitarian positions can be discerned throughout the history of ethical theory.
Though there are many varieties of the view discussed, utilitarianism is generally held to be the view that the morally right action is the action that produces the most good. There are many ways to spell out this general claim. One thing to note is that the theory is a form of consequentialism: the right action is understood entirely in terms of consequences produced. What distinguishes utilitarianism from egoism has to do with the scope of the relevant consequences. On the utilitarian view one ought to maximize the overall good — that is, consider the good of others as well as one's own good.
The Classical Utilitarians, Jeremy Bentham and John Stuart Mill, identified the good with pleasure, so, like Epicurus, were hedonists about value. They also held that we ought to maximize the good, that is, bring about ‘the greatest amount of good for the greatest number’.
Utilitarianism is also distinguished by impartiality and agent-neutrality. Everyone's happiness counts the same. When one maximizes the good, it is the good impartially considered. My good counts for no more than anyone else's good. Further, the reason I have to promote the overall good is the same reason anyone else has to so promote the good. It is not peculiar to me.
All of these features of this approach to moral evaluation and/or moral decision-making have proven to be somewhat controversial and subsequent controversies have led to changes in the Classical version of the theory.
John Stuart Mill (1806-1873) was a follower of Bentham, and, through most of his life, greatly admired Bentham's work even though he disagreed with some of Bentham's claims —