- **Empiricism** - The theory that all knowledge is derived from sense-experience. - **Rationalism** - The belief in or reliance on reason as the best guide for belief and action. - **Existentialism** - A philosophical theory that emphasizes individual existence, freedom, and choice. - **Utilitarianism** - The doctrine that actions are right if they are useful or for the benefit of a majority. - **Determinism** - The philosophical belief that all events, including moral choices, are determined completely by previously existing causes. - **Egalitarianism** - A belief in human equality especially with respect to social, political, and economic affairs. - **Relativism** - The doctrine that knowledge, truth, and morality exist in relation to culture, society, or historical context, and are not absolute. - **Altruism** - The belief in or practice of disinterested and selfless concern for the well-being of others. - **Nihilism** - The rejection of all religious and moral principles, in the belief that life is meaningless. - **Pragmatism** - A philosophical tradition that began in the United States in the late 19th century, which asserts that the truth of beliefs is determined by their usefulness and practical outcomes. existential crises are inner conflicts characterized by the impression that life lacks meaning or by confusion about one's personal identity