Altruism (also called the ethic of altruism, moralistic altruism, and ethical altruism) is an ethical doctrine that holds that individuals have a moral obligation to help, serve, or benefit others, if necessary at the sacrifice of self interest. Auguste Comte's version of altruism calls for living for the sake of others. One who holds to either of these ethics is known as an "altruist."

The word "altruism" (French, altruisme, from autrui: "other people", derived from Latin alter: "other") was coined by Auguste Comte, the French founder of positivism, in order to describe the ethical doctrine he supported. He believed that individuals had a moral obligation to renounce self-interest and live for others. Comte says, in his Catéchisme Positiviste, that:

[The] social point of view cannot tolerate the notion of rights, for such notion rests on individualism. We are born under a load of obligations of every kind, to our predecessors, to our successors, to our contemporaries. After our birth these obligations increase or accumulate, for it is some time before we can return any service.... This ["to live for others"], the definitive formula of human morality, gives a direct sanction exclusively to our instincts of benevolence, the common source of happiness and duty. [Man must serve] Humanity, whose we are entirely."