A central concept both in ethics and epistemology. An action or a belief is justified if it stands up to some kind of critical reflection or scrutiny; a person is then exempt from criticism on account of it. The philosophical question is one of the standards that have to be met and the source of their authority. A surprisingly popular line of thought in epistemology is that ‘only a belief can justify another belief’ (Davidson). The implication that neither experience nor the world plays a role in justifying beliefs leads quickly to coherentism.