Alethiology

Alethiology (or Alethology) literally means 'the study of truth', but can more accurately be translated as 'the study of the nature of truth'. It could be argued that this is synonymous with epistemology, the study of knowledge, and that dividing the two is mere semantics, but there is a definite distinction between the two. Epistemology is the study of knowledge and its acquisition. Alethiology is more specifically concerned with the nature of truth. What is truth, rather than what facts are true or how they become known.

No doubt affirming just what truth is has a rich philosophical history. The Polish logician Alfred Tarski studied the criteria that a definition of ‘true sentence’ should meet, and these included that the truth in an "object language" L had to be ascertainable or definable in a "metalanguage," M, which would be a language of some kind of higher order logic. Additionally, according to the online Stanford Encyclopedia of Philosophy, "This means that it should be a sentence of the form

   For all x, True(x) if and only if φ(x), 

where True never occurs in φ; or failing this, that the definition should be provably equivalent to a sentence of this form." Finally, and again from the Stanford Encyclopedia of Philosophy, the definition should be "materially adequate," which means that "the objects satisfying φ should be exactly the objects that we would intuitively count as being true sentences of L, and that this fact should be provable from the axioms of the metalanguage." If this appears paradoxical, Tarski avoids the paradox by "using (in general) infinitely many sentences of M to express truth, namely all the sentences of the form: φ(s) if and only if ψ, whenever s is the name of a sentence S of L and ψ is the copy of S in the metalanguage."

Two very common truth definitions are the correspondence theory and the coherence theory. The correspondence theory of truth is something of a positivist theory, and simply states that something is true if it accords with experience, with facts as they are known and interpreted. In short, a belief is true if and only if it corresponds to a fact. The theory is a kind of realism, and purports that the world exists objectively, independently of the ways we think about it or describe it, and that our thoughts and claims are about that world. This theory has been associated with, among others, G. E. Moore and Bertrand Russell.

Another theory of truth that is usually placed alongside the correspondence theory is the coherence theory of truth. In this theory, an idea or belief can be true if its internal elements are consistent and cohere. H.H. Joachim, wrote in his The Nature of Truth, (1906) that "Truth in its essential nature is that systematic coherence which is the character of a significant whole" (76).

There are numerous other subtle theories of truth, associated with language, propositions, meaning, and truth conditions. See the online Stanford Encyclopedia of Philosophy for extensive details.

The Encyclopædia Britannica Eleventh Edition describes the discipline as "…an uncommon expression for the doctrine of truth, used by Sir William Hamilton in his philosophic writings when treating of the rules for the discrimination of truth and error."