에기스토스 (Egoism) is a philosophical theory that emphasizes self-interest as the foundation of moral behavior. It suggests that individuals should act in ways that promote their own well-being and happiness. This perspective contrasts with altruism, which prioritizes the welfare of others over oneself. There are different forms of egoism, including ethical egoism, which argues that individuals ought to act in their own best interest, and psychological egoism, which posits that people naturally act in ways that benefit themselves. Critics of egoism argue that it can lead to selfishness and disregard for the needs of others.