Rational egoism

Rational egoism (also called rational selfishness) is the principle that an action is rational if and only if it maximizes one's self-interest. As such, it is considered a normative form of egoism, though historically it has been associated with both positive and normative forms. In its strong form, rational egoism holds that to not pursue one's own interest is unequivocally irrational. Its weaker form, however, holds that while it is rational to pursue self-interest, failing to pursue self-interest is not always irrational.

Originally an element of nihilist philosophy in Russia, it was later popularised in English-speaking countries by Russian-American author Ayn Rand.