Truth is that which corresponds to reality or fact. A statement is true if what it says is the case. The correspondence theory of truth, defended by Aristotle and Aquinas, holds that truth is a relation between a proposition and the world. The coherence theory holds that truth is a matter of consistency within a system of beliefs. The pragmatist theory holds that truth is what works, what enables successful action. Each theory captures something, but none is universally accepted. The debate about truth is one of the oldest in philosophy.

Truth is not the same as belief. You can believe something false. It is not the same as opinion. Opinions can be true or false. It is not the same as certainty. You can be certain and wrong. Truth is objective, on most accounts. It does not depend on what anyone thinks. But some philosophers argue that truth is relative to a framework, a culture, or an individual. The debate between objectivism and relativism about truth is one of the most consequential in philosophy. It shapes how we think about science, religion, politics, and everyday life. Truth is the standard against which beliefs are measured.

Theories of truth

• Correspondence. Truth is agreement with reality.
• Coherence. Truth is consistency within a system.
• Pragmatic. Truth is what works in practice.
• Deflationary. Truth is a redundant concept.

Truth is not the same as fact. A fact is a state of affairs. Truth is a property of statements about facts.