Truth

Truth or verity is the property of being in accord with fact or reality. In everyday language, it is typically ascribed to things that aim to represent reality or otherwise correspond to it, such as beliefs, propositions, and declarative sentences.

True statements are usually held to be the opposite of false statements. The concept of truth is discussed and debated in various contexts, including philosophy, art, theology, law, and science. Most human activities depend upon the concept, where its nature as a concept is assumed rather than being a subject of discussion, including journalism and everyday life. Some philosophers view the concept of truth as basic, and unable to be explained in any terms that are more easily understood than the concept of truth itself. Most commonly, truth is viewed as the correspondence of language or thought to a mind-independent world. This is called the correspondence theory of truth.

Various theories and views of truth continue to be debated among scholars, philosophers, and theologians. There are many different questions about the nature of truth which are still the subject of contemporary debates. These include the question of defining truth; whether it is even possible to give an informative definition of truth; identifying things as truth-bearers capable of being true or false; if truth and falsehood are bivalent, or if there are other truth values; identifying the criteria of truth that allows people to identify it and to distinguish it from falsehood; the role that truth plays in constituting knowledge; and, if truth is always absolute or if it can be relative to one's perspective.

The English word truth is derived from Old English triewth, Middle English trewthe, as a -th nominalisation of the adjective true (Old English treowe). In ordinary usage, the word may denote either a quality of "faithfulness, fidelity, loyalty, sincerity, veracity", or that of "agreement with fact or reality".

The adjective, cognate with German treu 'faithful', stems from Proto-Germanic *trewwj- 'having good faith', and perhaps ultimately from Proto-Indo-European *dru- 'tree', on the notion of "steadfast as an oak" (cf. Sanskrit dā́ru '(piece of) wood'; Old Norse trú 'faith, word of honour, belief').

The question of what is a proper basis for deciding how words, symbols, ideas and beliefs may properly be considered true, whether by a single person or an entire society, is dealt with by the five most prevalent substantive theories of truth listed below. Each presents perspectives that are widely shared by published scholars.

Theories other than the most prevalent substantive theories are also discussed. According to a survey of professional philosophers and others on their philosophical views which was carried out in November 2009 (taken by 3226 respondents, including 1803 philosophy faculty members and/or PhDs and 829 philosophy graduate students) 45% of respondents accept or lean toward correspondence theories, 21% accept or lean toward deflationary theories and 14% epistemic theories.

Correspondence theories emphasize that true beliefs and true statements correspond to the actual state of affairs. This type of theory stresses a relationship between thoughts or statements on one hand, and things or objects on the other. It is a traditional model tracing its origins to ancient Greek philosophers such as Socrates, Plato, and Aristotle. This class of theories holds that the truth or the falsity of a representation is determined in principle entirely by how it relates to "things" according to whether it accurately describes those "things". A classic example of correspondence theory is the statement by the thirteenth century philosopher and theologian Thomas Aquinas: "Veritas est adaequatio rei et intellectus" ("Truth is the adequation of things and intellect"), which Aquinas attributed to the ninth century Neoplatonist Isaac Israeli. Aquinas also restated the theory as: "A judgment is said to be true when it conforms to the external reality".