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This article is primarily concerned with truth as it is used in the evaluation of assertions. For example, It is true that the world is a sphere. When used in this way, it is properly contrasted with false. Truth is a concept of primary importance to philosophy, science, law, and religion. See also objectivity.

Table of contents
1 Theories of truth
2 True testimony
3 Other uses of true
4 Quotations
5 See also
6 References

Theories of truth

The study of truth is part of philosophical logic and epistemology. Sentences, propositions, statements, ideas, beliefs, and judgments can be true, and are called truth bearers by philosophers.

There are several broad theories about truth that philosophers and logicians have proposed.

Each can be interpreted as either a definition of the fundamental nature of truth, or as a criterion for determining truth values. So, for instance, a realist might define truth as correspondence with the facts, and argue that the only valid way to determine the truth of a proposition is to see if it corresponds to the facts. A Coherentist might also define truth as correspondence with mind-independent reality, but also maintain that the truth or falsity of a statement is determined by its cohering with the body of accepted scientific knowledge. Pierce in his later writings thought that truth was defined as correspondence with reality, but held that the truth or falsity of a proposal was determined by the agreement of the relevant experts.

The semantic theory of truth has as its general case for a given language:

'P' is true if and only if P
where 'P' is a reference to the sentence (the sentence's name), and P is just the sentence itself. The semantic theory can be applied to languages with a denumerable number of sentences. In a natural language such as English this process consists simply of quoting the sentence, so:
'Snow is white' is true iff snow is white
This definition of truth has also been called the disquotation, since the term on the right is simply the term on the left, without the quotes.

Its inventor, philosopher-logician Alfred Tarski, thought of it as a species of correspondence theory, in which the term on the right is assumed to correspond to the facts. On this account, to say that 'P is true' is to do no more than to assert P. In this regard, it can also be considered a form of the deflationary theory of truth.

Deflationary theories, after Gottlob Frege and F. P. Ramsey, also point out that "truth" is not the name of some property of propositions — some thing about which one could have a theory. The belief that truth is a property is just an illusion caused by the fact that we have the predicate "is true" in our language. Since most predicates name properties, we naturally assume that "is true" does as well. But, they say, statements that seem to predicate truth are actually doing nothing more than signal agreement with the statement. For example, the redundancy theory of truth holds that to assert that a statement is true is just to assert the statement itself. Thus, to say that "It is true that snow is white" is to say nothing more nor less than that show is white. A second example is the performative theory of truth which holds that to say "It is true that snow is white" is to perform the speech act of signalling one's agreement with the claim that snow is white (much like nodding one's head in agreement). The idea that some statements are more actions than communicative statements is not as odd as it may seem. Consider, for example, that when the bride says "I do" at the appropriate time in a wedding, she is performing the act of taking this man to be her lawful wedded husband. She is not describing herself as taking this man.

Subjective vs. objective

Subjective truths are those with which we are most intimately acquainted. That I like broccoli or that I have a pain in my foot are both subjectively true. Metaphysical subjectivism holds that all we have are such truths. That is, that all we can know about are, one way or another, our own subjective experiences. This view does not necessarily reject realism. But at the least claims that we cannot have direct knowledge eof the real world.

In contrast, Objective truths are supposed in some way to be independent of our subjective beliefs and tastes. Such truths would subsist not in the mind but in the external object. Maurice Merleau-Ponty argued that grasping such truths requires one to view the world from everywhere at once, a facility only God might achieve.

Relative vs. absolute

Relative truths are statements or propositions that are true only relative to some standard or convention. That the fork is to the left of the spoon depends on where one stands, and so is a relative truth.

Usually the standard cited is the tenets of one's own culture. Relativism is the doctrine that all truths within a particular domain are of this form, and entails that what is true varies across cultures and eras. Its logical structure is dealt with in the article on the relativist fallacy. Moral relativism is the view that moral truths are socially determined.

Relative truths can be contrasted with absolute truths. The latter are statements or propositions that are taken to be true for all cultures and all eras. For example, for Muslims Allahu Akbar expresses an absolute truth; for the micro economist, that the laws of supply and demand determine the value of any consumable in a market economy is true in all situations; for the Kantian, "act only according to that maxim by which you can at the same time will that it should become a universal law" forms an absolute moral truth. They are truths that are claimed to emanate from the very nature of the universe, God, or some other ultimate essence or transcendental signifier.

Surprisingly, truths advocated as absolute tend to be those of the powerful in the culture of the advocate.

Absolutism in a particular domain of thought is the view that all statements in that domain are either absolutely true or absolutely false: none is true for some cultures or eras while false for other cultures or eras. For example, Moral Absolutism is the view that moral claims such as "Abortion is wrong" or "Charity is good" are either true for all people in all times or false for all people in all times.

True testimony

Witnesses who swear under oath to testify truthfully in courts of law, are not expected to make infallibly true statements, but to make a good faith attempt to recount an observed event from their memory or provide expert testimony. That what one witness says may differ from true accounts of other witnesses is a commonplace occurrence in the practice of law. Triers-of-fact are then charged with the responsibility to determine the credibility or veracity of a witness' testimony.

Other uses of true

In addition to its use in reference to propositions, there are other uses of "truth" and "true" in English:

The first is most often applied to people, and is used as a commendation, synonymous with "loyal", as in she is true to her friends. This sense of truth should be contrasted with being fake, insincere, misleading and so on.

Second, "true" can mean "in accordance with a standard or archetype," which is how it is used in "He is a true Englishman."

Third, "true" can be used as a verb meaning "to straighten the spokes of a bicycle wheel."


See also

Truth in logic

Major philosophers who have proposed theories of truth