• German: Wahrheit
• Irish: fírinne

• Finnish: totuus
• German: Wahrheit
• Irish: fírinne
• Russian: истина

• ttbc Arabic:
• ttbc Aramaic:

  Syriac: ܫܪܪܐ (shrārā, shroro)

  Hebrew: שררא (shrārā, shroro)

• ttbc Breton: gwirionez
• ttbc Bulgarian: истина (ístina)
• ttbc Cebuano: kamatuoran
• ttbc Chinese: 事實, 事实 (shìshí)
• ttbc Croatian: istina
• ttbc Czech: pravda
• ttbc Danish: sandhed
• ttbc Dutch: waarheid
• ttbc Esperanto: vero
• ttbc Estonian: tõde
• ttbc Ewe: nyateƒe
• ttbc French: vérité
• ttbc Greek: αλήθεια
• ttbc Hebrew: אמת (emet)
• ttbc Hungarian: igazság
• ttbc Icelandic: sannleikur
• ttbc Ido: vera
• ttbc Indonesian: kebenaran
• ttbc Italian: verità
• ttbc Japanese: 真実 (しんじつ, shinjitsu), 本当 (ほんとう, hontō), 心理　(しんり, shinri)
• ttbc Kannada: ನನ್ನಿ
• ttbc Korean: 진실 (jinsil), 진리 (jilli), 참됨 (chamdoem)
• ttbc Kurdish:
• ttbc Latin: veritas
• ttbc Macedonian: вистина (vistina)
• ttbc Malayalam: സത്യം (sathyam), നേര് (neru)
• ttbc Northern Sami: duohtavuohta
• ttbc Norwegian: sannhet
• ttbc Occitan: vertat
• ttbc Persian: (dorosti)
• ttbc Polish: prawda
• ttbc Portuguese: verdade
• ttbc Romanian: adevăr
• ttbc Serbian: istina
• ttbc Slovak: pravda
• ttbc Slovene: resnica
• ttbc Spanish: verdad
• ttbc Swahili: kweli (class 9/10)
• ttbc Welsh: gwir

The meaning of the word truth extends from honesty, good faith, and sincerity in general, to agreement with fact or reality in particular. The term has no single definition about which the majority of professional philosophers and scholars agree. Various theories of truth continue to be debated. There are differing claims on such questions as what constitutes truth; how to define and identify truth; the roles that revealed and acquired knowledge play; and whether truth is subjective, relative, objective, or absolute. This article introduces the various perspectives and claims, both today and throughout history.

The major theories of truth

The 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 a principal focus of the five substantive theories introduced below. These theories each present perspectives that are widely shared by published scholars. There also have more recently arisen "deflationary" or "minimalist" theories of truth based on the idea that the application of a term like true to a statement does not assert anything significant about it, for instance, anything about its nature, but that the label truth is a tool of discourse used to express agreement, to emphasize claims, or to form certain types of generalizations. Some post-modern thinkers assert that what passes for truth is in fact, merely, the mass consensus of the public. This would entail that no effort, or application of theory or experiment, is required to arrive at truth, which is in effect only a by-product of social change.

Substantive theories

Correspondence theory

Correspondence theories state that true beliefs and true statements correspond to the actual state of affairs. This type of theory attempts to posit a relationship between thoughts or statements on the one hand, and things or objects on the other. It is a traditional model which goes back at least to some of the classical 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 solely by how it relates to objective reality, by whether it accurately describes that reality. For example, there is a true distance to the moon when we humans attempt to go there, and this true distance is necessary to know so that the journey can be successfully made.

Correspondence theory states that truth is a matter of accurately copying "objective reality" and then representing it in thoughts, words and other symbols. A major proponent of this theory is the Christian philosopher Thomas Aquinas, who said that "Truth is the conformity of the intellect with things." He said that real things participate in the act of being of the Creator God who is Subsistent Being, Intelligence, and Truth. Thus, these beings possess the light of intelligibility and are knowable. These things (beings; reality) are the foundation of the truth that is found in the human mind, when it acquires knowledge of things, first through the senses, then through the understanding and the judgement done by reason. For Aquinas, human intelligence ("intus", within and "legere", to read) has the capability to reach the essence and existence of things because it is an immaterial, spiritual power.

Coherence theory

More modern theorists have stated that the idea behind correspondence theory cannot be achieved independently of some analysis of additional factors. Proponents of several of these other theories have gone farther to assert that there are yet other issues necessary to the analysis, such as language and its translation to other languages, interpersonal power struggles, community interactions, personal biases and other factors involved in deciding what is seen as truth.

For coherence theories in general, truth requires a proper fit of elements within a whole system. Very often, though, coherence is taken to imply something more than simple logical consistency; often there is a demand that the propositions in a coherent system lend mutual inferential support to each other. So, for example, the completeness and comprehensiveness of the underlying set of concepts is a critical factor in judging the validity and usefulness of a coherent system. A pervasive tenet of coherence theories is the idea that truth is primarily a property of whole systems of propositions, and can be ascribed to individual propositions only according to their coherence with the whole. Among the assortment of perspectives commonly regarded as coherence theory, theorists differ on the question of whether coherence entails many possible true systems of thought or only a single absolute system.

Some variants of coherence theory are claimed to characterize the essential and intrinsic properties of formal systems in logic and mathematics. However, formal reasoners are content to contemplate axiomatically independent and sometimes mutually contradictory systems side by side, for example, the various alternative geometries. On the whole, coherence theories have been criticized as lacking justification in their application to other areas of truth, especially with respect to assertions about the natural world, empirical data in general, assertions about practical matters of psychology and society, especially when used without support from the other major theories of truth.

Coherence theories distinguish the thought of rationalist philosophers, particularly of Spinoza, Leibniz, and G.W.F. Hegel, along with the British philosopher F.H. Bradley. They have found a resurgence also among several proponents of logical positivism, notably Otto Neurath and Carl Hempel.

Constructivist theory

Social constructivism holds that truth is constructed by social processes, is historically and culturally specific, and that it is in part shaped through the power struggles within a community. Constructivism views all of our knowledge as "constructed," because it does not reflect any external "transcendent" realities (as a pure correspondence theory might hold). Rather, perceptions of truth are viewed as contingent on convention, human perception, and social experience. It is believed by constructivists that representations of physical and biological reality, including race, sexuality, and gender are socially constructed. Giambattista Vico was among the first to claim that history and culture were man-made. Vico's epistemological orientation gathers the most diverse rays and unfolds in one axiom--verum ipsum factum--"truth itself is constructed." Hegel, Garns, and Marx were among the other early proponents of the premise that truth is socially constructed.

Consensus theory

Consensus theory holds that truth is whatever is agreed upon, or in some versions, might come to be agreed upon, by some specified group. Such a group might include all human beings, or a subset thereof consisting of more than one person.

Among the current advocates of consensus theory as a useful accounting of the concept of "truth" is the philosopher Jürgen Habermas. Habermas maintains that truth is what would be agreed upon in an ideal speech situation. Among the current strong critics of consensus theory is the philosopher Nicholas Rescher.

Pragmatic theory

The three most influential forms of the pragmatic theory of truth were introduced around the turn of the 20th century by Charles S. Peirce, William James, and John Dewey. Although there are wide differences in viewpoint among these and other proponents of pragmatic theory, they hold in common that truth is verified and confirmed by the results of putting one's concepts into practice.

Peirce defines truth as follows: "Truth is that concordance of an abstract statement with the ideal limit towards which endless investigation would tend to bring scientific belief, which concordance the abstract statement may possess by virtue of the confession of its inaccuracy and one-sidedness, and this confession is an essential ingredient of truth." This statement emphasizes Peirce's view that ideas of approximation, incompleteness, and partiality, what he describes elsewhere as fallibilism and "reference to the future", are essential to a proper conception of truth. Although Peirce uses words like concordance and correspondence to describe one aspect of the pragmatic sign relation, he is also quite explicit in saying that definitions of truth based on mere correspondence are no more than nominal definitions, which he accords a lower status than real definitions.

William James's version of pragmatic theory, while complex, is often summarized by his statement that "the 'true' is only the expedient in our way of thinking, just as the 'right' is only the expedient in our way of behaving." By this, James meant that truth is a quality the value of which is confirmed by its effectiveness when applying concepts to actual practice (thus, "pragmatic").

John Dewey, less broadly than James but more broadly than Peirce, held that inquiry, whether scientific, technical, sociological, philosophical or cultural, is self-corrective over time if openly submitted for testing by a community of inquirers in order to clarify, justify, refine and/or refute proposed truths.

Minimalist (deflationary) theories

A number of philosophers reject the thesis that the concept or term truth refers to a real property of sentences or propositions. These philosophers are responding, in part, to the common use of truth predicates (e.g., that some particular thing "...is true") which was particularly prevalent in philosophical discourse on truth in the first half of the 20th century. From this point of view, to assert the proposition “'2 + 2 = 4' is true” is logically equivalent to asserting the proposition “2 + 2 = 4”, and the phrase “is true” is completely dispensable in this and every other context. These positions are broadly described

• as deflationary theories of truth, since they attempt to deflate the presumed importance of the words "true" or truth,
• as disquotational theories, to draw attention to the disappearance of the quotation marks in cases like the above example, or
• as minimalist theories of truth.

Whichever term is used, deflationary theories can be said to hold in common that "[t]he predicate 'true' is an expressive convenience, not the name of a property requiring deep analysis."

Performative theory of truth

Attributed to P. F. Strawson is the performative theory of truth which holds that to say "'Snow is white' is true" is to perform the speech act of signaling 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. In a similar way, Strawson holds: "To say a statement is true is not to make a statement about a statement, but rather to perform the act of agreeing with, accepting, or endorsing a statement. When one says 'It's true that it's raining,' one asserts no more than 'It's raining.' The function of [the statement] 'It's true that...' is to agree with, accept, or endorse the statement that 'it's raining.'"

Redundancy and related theories

According to the redundancy theory of truth, asserting that a statement is true is completely equivalent to asserting the statement itself. For example, making the assertion that " 'Snow is white' is true" is equivalent to asserting "Snow is white". Redundancy theorists infer from this premise that truth is a redundant concept; that is, it is merely a word that is traditionally used in conversation or writing, generally for emphasis, but not a word that actually equates to anything in reality. This theory is commonly attributed to Frank P. Ramsey, who held that the use of words like fact and truth was nothing but a roundabout way of asserting a proposition, and that treating these words as separate problems in isolation from judgment was merely a "linguistic muddle".

A variant of redundancy theory is the disquotational theory which uses a modified form of Tarski's schema: To say that '"P" is true' is to say that P. Yet another version of deflationism is the prosentential theory of truth, first developed by Dorothy Grover, Joseph Camp, and Nuel Belnap as an elaboration of Ramsey's claims. They argue that sentences like "That's true", when said in response to "It's raining", are prosentences, expressions that merely repeat the content of other expressions. In the same way that it means the same as my dog in the sentence My dog was hungry, so I fed it, That's true is supposed to mean the same as It's raining — if you say the latter and I then say the former. These variations do not necessarily follow Ramsey in asserting that truth is not a property, but rather can be understood to say that, for instance, the assertion "P" may well involve a substantial truth, and the theorists in this case are minimalizing only the redundancy or prosentence involved in the statement such as "that's true." or under all possible interpretations, as contrasted to a synthetic claim (or fact) which is only true in this world as it has historically unfolded. Logical truths are necessarily true. A proposition such as “If p and q, then p.” and the proposition “All husbands are married.” are considered to be logical truths because they are true because of their meanings and not because of any facts of the world. They are such that they could not be untrue.

Logic is concerned with the patterns in reason that can help tell us if a proposition is true or not. However, logic does not deal with truth in the absolute sense, as for instance a metaphysician does. Logicians use formal languages to express the truths which they are concerned with, and as such there is only truth under some interpretation or truth within some logical system.

Truth in mathematics

There are two main approaches to truth in mathematics. They are the model theory of truth and the proof theory of truth.

Historically, with the nineteenth century development of Boolean algebra mathematical models of logic began to treat "truth", also represented as "T" or "1", as an arbitrary constant. "Falsity" is also an arbitrary constant, which can be represented as "F" or "0". In propositional logic, these symbols can be manipulated according to a set of axioms and rules of inference, often given in the form of truth tables.

In addition, from at least the time of Hilbert's program at the turn of the twentieth century to the proof of Gödel's theorem and the development of the Church-Turing thesis in the early part of that century, true statements in mathematics were generally assumed to be those statements which are provable in a formal axiomatic system.

The works of Kurt Gödel, Alan Turing, and others shook this assumption, with the development of statements that are true but cannot be proven within the system. Two examples of the latter can be found in Hilbert's problems. Work on Hilbert's 10th problem led in the late twentieth century to the construction of specific Diophantine equations for which it is undecidable whether they have a solution, or even if they do, whether they have a finite or infinite number of solutions. More fundamentally, Hilbert's first problem was on the continuum hypothesis. Gödel and Paul Cohen showed that this hypothesis cannot be proved or disproved using the standard axioms of set theory and a finite number of proof steps. In the view of some, then, it is equally reasonable to take either the continuum hypothesis or its negation as a new axiom.

Semantic theory of truth

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.

Logician and philosopher Alfred Tarski developed the theory for formal languages (such as formal logic). Here he restricted it in this way: no language could contain its own truth predicate, that is, the expression is true could only apply to sentences in some other language. The latter he called an object language, the language being talked about. (It may, in turn, have a truth predicate that can be applied to sentences in still another language.) The reason for his restriction was that languages that contain their own truth predicate will contain paradoxical sentences like the Liar: This sentence is not true. See The Liar paradox. As a result Tarski held that the semantic theory could not be applied to any natural language, such as English, because they contain their own truth predicates. Donald Davidson used it as the foundation of his truth-conditional semantics and linked it to radical interpretation in a form of coherentism.

Bertrand Russell is credited with noticing the existence of such paradoxes even in the best symbolic formalizations of mathematics in his day, in particular the paradox that came to be named after him, Russell's paradox. Russell and Whitehead attempted to solve these problems in Principia Mathematica by putting statements into a hierarchy of types, wherein a statement cannot refer to itself, but only to statements lower in the hierarchy. This in turn led to new orders of difficulty regarding the precise natures of types and the structures of conceptually possible type systems that have yet to be resolved to this day.

Kripke's theory of truth

Saul Kripke contends that a natural language can in fact contain its own truth predicate without giving rise to contradiction. He showed how to construct one as follows:

• Begin with a subset of sentences of a natural language that contains no occurrences of the expression "is true" (or "is false"). So The barn is big is included in the subset, but not " The barn is big is true", nor problematic sentences such as "This sentence is false".

• Define truth just for the sentences in that subset.

• Then extend the definition of truth to include sentences that predicate truth or falsity of one of the original subset of sentences. So "The barn is big is true" is now included, but not either "This sentence is false" nor "The barn is big is true' is true".

• Next, define truth for all sentences that predicate truth or falsity of a member of the second set. Imagine this process repeated infinitely, so that truth is defined for The barn is big; then for "The barn is big is true"; then for "The barn is big is true' is true", and so on.

Notice that truth never gets defined for sentences like This sentence is false, since it was not in the original subset and does not predicate truth of any sentence in the original or any subsequent set. In Kripke's terms, these are "ungrounded." Since these sentences are never assigned either truth or falsehood even if the process is carried out infinitely, Kripke's theory implies that some sentences are neither true nor false. This contradicts the Principle of bivalence: every sentence must be either true or false. Since this principle is a key premise in deriving the Liar paradox, the paradox is dissolved.

Notable philosophers' views

Ancient philosophers

The ancient Greek origins of the words "true" and "truth" have some consistent definitions throughout great spans of history that were often associated with topics of logic, geometry, mathematics, deduction, induction, and natural philosophy.

Socrates', Plato's and Aristotle's ideas about truth are commonly seen as consistent with correspondence theory. In his Metaphysics, Aristotle stated: “To say of what is that it is not, or of what is not that it is, is false, while to say of what is that it is, and of what is not that it is not, is true”. The Stanford Encyclopedia of Philosophy proceeds to say of Aristotle:

Aristotle sounds much more like a genuine correspondence theorist in the Categories (12b11, 14b14), where he talks of “underlying things” that make statements true and implies that these “things” (pragmata) are logically structured situations or facts (viz., his sitting, his not sitting). Most influential is his claim in De Interpretatione (16a3) that thoughts are “likenessess” (homoiosis) of things. Although he nowhere defines truth in terms of a thought's likeness to a thing or fact, it is clear that such a definition would fit well into his overall philosophy of mind.

In the Upanishads of ancient India, truth is Sat (pronounced Sah't), the one reality and existence, which is directly experienced by the Rishi or sage (see also Gandhi section below). The Rishi discovers that which exists, Sat, as the truth of one's own being, the Atma or self, and as the truth of the being of God, Ishvara.

Medieval philosophers

In early Islamic philosophy, Avicenna (Ibn Sina) defined truth as:

Avicenna elaborated on his definition of truth in his Metaphysics:

Following Avicenna, and also Augustine and Aristotle, Thomas Aquinas stated in his Disputed Questions on Truth:

Thus, for Thomas, the truth of the human intellect (logical truth) is based on the truth in things (ontological truth). Following this, he wrote an elegant re-statement of Aristotle's view in his Summa I.16.1:

Modern philosophers

Kant

Immanuel Kant discussed the correspondence theory of truth According to Kant, the definition of truth as correspondence is a "mere verbal definition", here making use of Aristotle's distinction between a nominal definition, a definition in name only, and a real definition, a definition that shows the true cause or essence of the thing whose term is being defined. From Kant's account of the history, the definition of truth as correspondence was already in dispute from classical times, the "skeptics" criticizing the "logicians" for a form of circular reasoning, though the extent to which the "logicians" actually held such a theory is not evaluated.

While objective truths are final and static, subjective truths are continuing and dynamic. The truth of one's existence is a living, inward, and subjective experience that is always in the process of becoming. The values, morals, and spiritual approaches a person adopts, while not denying the existence of objective truths of those beliefs, can only become truly known when they have been inwardly appropriated through subjective experience. Thus, Kierkegaard criticizes all systematic philosophies which attempt to know life or the truth of existence via theories and objective knowledge about reality. As Kierkegaard claims, human truth is something that is continually occurring, and a human being cannot find truth separate from the subjective experience of one's own existing, defined by the values and fundamental essence that consist of one's way of life.

Nietzsche

Friedrich Nietzsche believed the search for truth or 'the will to truth' was a consequence of the will to power of philosophers. He thought that truth should be used as long as it promoted life and the will to power, and he thought untruth was better than truth if it had this life enhancement as a consequence. As he wrote in Beyond Good and Evil, "The falseness of a judgment is to us not necessarily an objection to a judgment... The question is to what extent it is life-advancing, life-preserving, species-preserving, perhaps even species-breeding..." (aphorism 4). He proposed the will to power as a truth only because according to him it was the most life affirming and sincere perspective one could have.

Robert Wicks discusses Nietzsche's basic view of truth as follows: Some scholars regard Nietzsche's 1873 unpublished essay, "On Truth and Lies in a Nonmoral Sense" ("Über Wahrheit und Lüge im außermoralischen Sinn") as a keystone in his thought. In this essay, Nietzsche rejects the idea of universal constants, and claims that what we call "truth" is only "a mobile army of metaphors, metonyms, and anthropomorphisms." His view at this time is that arbitrariness completely prevails within human experience: concepts originate via the very artistic transference of nerve stimuli into images; "truth" is nothing more than the invention of fixed conventions for merely practical purposes, especially those of repose, security and consistence.

Heidegger

Gandhi

Mohandas "Mahatma" Gandhi dedicated his life to the wider purpose of discovering truth, or Satya. He tried to achieve this by learning from his own mistakes and conducting experiments on himself. He called his autobiography The Story of My Experiments with Truth. Gandhi stated that the most important battle to fight was overcoming his own demons, fears, and insecurities. Gandhi summarized his beliefs first when he said "God is Truth". He would later change this statement to "Truth is God".

Whitehead

Alfred North Whitehead a British mathematician who became an American philosopher, said: "There are no whole truths; all truths are half-truths. It is trying to treat them as whole truths that play the devil".

The logical progression or connection of this line of thought is to conclude that truth can lie, since half-truths are deceptive and may lead to a false conclusion.

Nishida

According to Kitaro Nishida, "knowledge of things in the world begins with the differentiation of unitary consciousness into knower and known and ends with self and things becoming one again. Such unification takes form not only in knowing but in the valuing (of truth) that directs knowing, the willing that directs action, and the feeling or emotive reach that directs sensing."

Fromm

Erich Fromm finds that trying to discuss truth as "absolute truth" is sterile and that emphasis ought to be placed on "optimal truth". He considers truth as stemming from the survival imperative of grasping one's environment physically and intellectually, whereby young children instinctively seek truth so as to orient themselves in "a strange and powerful world". The accuracy of their perceived approximation of the truth will therefore have direct consequences on their ability to deal with their environment. Fromm can be understood to define truth as a functional approximation of reality. His vision of optimal truth is described partly in "Man from Himself: An Inquiry into the Psychology of Ethics" (1947), from which excerpts are included below.

the dichotomy between 'absolute = perfect' and 'relative = imperfect' has been superseded in all fields of scientific thought, where "it is generally recognized that there is no absolute truth but nevertheless that there are objectively valid laws and principles".

In that respect, "a scientifically or rationally valid statement means that the power of reason is applied to all the available data of observation without any of them being suppressed or falsified for the sake of a desired result". The history of science is "a history of inadequate and incomplete statements, and every new insight makes possible the recognition of the inadequacies of previous propositions and offers a springboard for creating a more adequate formulation."

As a result "the history of thought is the history of an ever-increasing approximation to the truth. Scientific knowledge is not absolute but optimal; it contains the optimum of truth attainable in a given historical period." Fromm furthermore notes that "different cultures have emphasized various aspects of the truth" and that increasing interaction between cultures allows for these aspects to reconcile and integrate, increasing further the approximation to the truth.

Foucault

Truth, for Michel Foucault, is problematic when any attempt is made to see truth as an "objective" quality. He prefers not to use the term truth itself but "Regimes of Truth". In his historical investigations he found truth to be something that was itself a part of, or embedded within, a given power structure. Thus Foucault's view shares much in common with the concepts of Nietzsche. Truth for Foucault is also something that shifts through various episteme throughout history.

Baudrillard

Jean Baudrillard considered truth to be largely simulated, that is pretending to have something, as opposed to dissimulation, pretending to not have something. He took his cue from iconoclasts who he claims knew that images of God demonstrated the fact that God did not exist. Baudrillard wrote in "Precession of the Simulacra":

The simulacrum is never that which conceals the truth—it is the truth which conceals that there is none. The simulacrum is true.

—Ecclesiastes

Some example simulacra that Baudrillard cited were: that prisons simulate the "truth" that society is free; scandals (eg, Watergate) simulate that corruption is corrected; Disney simulates that the U.S. itself is an adult place. One must remember that though such examples seem extreme, such extremity is an important part of Baudrillard's philosophy. For a less extreme example consider how movies, almost without exception, end with the bad guy being punished, thus drilling into the viewers that successful businessmen and politicians are good or, if not, will be caught. conscience, freedom, and religion. He thinks that this self-limitation, which "amputates" the mind's capacity to answer fundamental questions such as man's origin and purpose, dishonors reason and is contradictory to the modern acclamation of science, whose basis is the power of reason.

For Ratzinger, truth and love are identical. And if well understood, according to him, this is "the surest guarantee of tolerance." Similarly, d'Holbach, in System of Nature, contrasts Mythology as an attempt to convey truth with theology as an attempt to obfuscate it.

Religious truth

Most religious traditions have a body of doctrine that adherents of that religion view as truth. This may take the form of a creed or catechism, it may refer to a book such as the Bible or the Koran, or it may be an unwritten code shared by believers. Unlike scientific truth or observed truth, religious truth often makes the claim of being either revealed or inspired by God.

When there is a clash between religious truth and scientific truth, various methods have been used to reconcile the two. During the Middle Ages, for example, there was conflict between Roman Catholic dogma on the one hand and an emerging body of scientific knowledge on the other. Sometimes the established church sought to suppress scientific truth, as in the case of Galileo, but sometimes the two truths were allowed to coexist, which led to the doctrine of the two truths. According to this compromise, there is a lesser truth, scientific truth, which holds that the earth orbits the sun, and a greater truth, religious truth, that holds that the earth is the fixed center of the universe. According to the doctrine of the two truths, these two truths were both true in their own sphere.

The modern Roman Catholic church has rejected the doctrine of two truths, and accepts as true all scientific truth. However, Christian Fundamentalism claims that religious truth should be accepted by scientists, and that if science were not corrupt it would recognize, for example, the occurrence of a universal flood. Thus the conflict between religious truth and scientific truth continues.

Scientific truth

See also Empirical truth.

Science seeks to approach truth through the scientific method. Strictly speaking, the scientific method never "proves" a theory or shows that it is definitely true. Except when it comes to directly observable facts, the scientific method never claims to reveal "the truth"; rather, it attempts to approach the truth by continuously refining theories so that they better approximate the truth.

Someone following the scientific method begins by collecting facts. Scientifically speaking, a fact is a directly observable, reproducible truth. A purported truth doesn't qualify as a fact if it's based on the observation of a single person. To qualify as a scientific fact, it must be based on repeated observations by many different scientists. For example, "When on Earth a rock is picked up from the ground and then released, it falls." qualifies as a scientific fact: it's directly observable and it's reproducible, because anyone can test it by picking up a rock and then letting go.

After collecting facts, a scientist formulates a hypothesis, a possible explanation for the facts. A hypothesis makes a suggestion as to what mechanism or relationship lies behind the observed facts. This relationship itself doesn't need to be directly observable. To qualify as scientific, a hypothesis must be falsifiable: that is, one must be able to imagine an experiment which, if carried out, could disprove the hypothesis.

The scientist then tests the hypothesis by making further observations (sometimes in a highly controlled environment such as a laboratory). Roughly speaking, if repeated observations support a hypothesis, then it qualifies as a theory.

The above is a very simplified account of the scientific method. In actual practice, most scientists begin their investigations by collecting more than raw facts. For example, many scientific hypothesis take an already-accepted scientific theory as one of the "facts" that support it or that it seeks to explain. For example, many theories in modern biology take the theory of evolution as part of their supporting evidence.

Examples of scientific theories which are accepted by almost all professional scientists include the germ theory of disease, Einstein's theory of relativity, and the theory of evolution. A scientific theory is often mathematical in nature.

“Nothing is too wonderful to be true, if it be consistent with the laws of nature, and in such things as these, experiment is the best test of such consistency.”, Schwinger 1969 quoting from M. Faraday.

Nomenclature and etymology

English truth is from Old English tríewþ, tréowþ, trýwþ, Middle English trewþe, cognate to Old High German triuwida, Old Norse tryggð. Like troth, it is a -th nominalisation of the adjective true (Old English tréowe).

English true is from Old English (West Saxon) (ge)tríewe, tréowe, cognate to Old Saxon (gi)trûui, Old High German (ga)triuwu (Modern German treu "faithful"), Old Norse tryggr, Gothic triggws, all from a Proto-Germanic *trewwj- "having good faith". Old Norse , holds the semantic field "faith, word of honour; religious faith, belief" (archaic English troth "loyalty, honesty, good faith", compare ).

Thus, 'truth' involves both the quality of "faithfulness, fidelity, loyalty, sincerity, veracity", and that of "agreement with fact or reality", in Anglo-Saxon expressed by sōþ.

All Germanic languages besides English have introduced a terminological distinction between truth "fidelity" and truth "factuality". To express "factuality", North Germanic opted for nouns derived from sanna "to assert, affirm", while continental West Germanic (German and Dutch) opted for continuations of wâra "faith, trust, pact" (cognate to Slavic věra "(religious) faith", but influenced by Latin verus). Romance languages use terms continuing Latin veritas, while Greek with aletheia and Slavic with pravda have unrelated terms.

Notes

References

• Aristotle, "The Categories", Harold P. Cooke (trans.), pp. 1–109 in Aristotle, Volume 1, Loeb Classical Library, William Heinemann, London, UK, 1938.

• Aristotle, "On Interpretation", Harold P. Cooke (trans.), pp. 111–179 in Aristotle, Volume 1, Loeb Classical Library, William Heinemann, London, UK, 1938.

• Aristotle, "Prior Analytics", Hugh Tredennick (trans.), pp. 181–531 in Aristotle, Volume 1, Loeb Classical Library, William Heinemann, London, UK, 1938.

• Aristotle, "On the Soul" (De Anima), W. S. Hett (trans.), pp. 1–203 in Aristotle, Volume 8, Loeb Classical Library, William Heinemann, London, UK, 1936.

• Audi, Robert (ed., 1999), The Cambridge Dictionary of Philosophy, Cambridge University Press, Cambridge, UK, 1995. 2nd edition, 1999. Cited as CDP.

• Baldwin, James Mark (ed., 1901–1905), Dictionary of Philosophy and Psychology, 3 volumes in 4, Macmillan, New York, NY.

• Baylis, Charles A. (1962), "Truth", pp. 321–322 in Dagobert D. Runes (ed.), Dictionary of Philosophy, Littlefield, Adams, and Company, Totowa, NJ.

• Benjamin, A. Cornelius (1962), "Coherence Theory of Truth", p. 58 in Dagobert D. Runes (ed.), Dictionary of Philosophy, Littlefield, Adams, and Company, Totowa, NJ.

• Blackburn, Simon, and Simmons, Keith (eds., 1999), Truth, Oxford University Press, Oxford, UK. Includes papers by James, Ramsey, Russell, Tarski, and more recent work.

• Chandrasekhar, Subrahmanyan (1987), Truth and Beauty. Aesthetics and Motivations in Science, University of Chicago Press, Chicago, IL.

• Chang, C.C., and Keisler, H.J., Model Theory, North-Holland, Amsterdam, Netherlands, 1973.

• Chomsky, Noam (1995), The Minimalist Program, MIT Press, Cambridge, MA.

• Church, Alonzo (1962a), "Name Relation, or Meaning Relation", p. 204 in Dagobert D. Runes (ed.), Dictionary of Philosophy, Littlefield, Adams, and Company, Totowa, NJ.

• Church, Alonzo (1962b), "Truth, Semantical", p. 322 in Dagobert D. Runes (ed.), Dictionary of Philosophy, Littlefield, Adams, and Company, Totowa, NJ.

• Clifford, W.K. (1877), "The Ethics of Belief and Other Essays". (Prometheus Books, 1999) http://www.infidels.org/library/historical/w_k_clifford/ethics_of_belief.html

• Dewey, John (1900–1901), Lectures on Ethics 1900–1901, Donald F. Koch (ed.), Southern Illinois University Press, Carbondale and Edwardsville, IL.

• Dewey, John (1932), Theory of the Moral Life, Part 2 of John Dewey and James H. Tufts, Ethics, Henry Holt and Company, New York, NY, 1908. 2nd edition, Holt, Rinehart, and Winston, 1932. Reprinted, Arnold Isenberg (ed.), Victor Kestenbaum (pref.), Irvingtion Publishers, New York, NY, 1980.

• Dewey, John (1938), Logic: The Theory of Inquiry (1938),Holt and Company, New York, NY. Reprinted, John Dewey, The Later Works, 1925–1953, Volume 12: 1938, Jo Ann Boydston (ed.), Southern Illinois University Press, Carbondale and Edwardsville, IL, 1986.

• Field, Hartry (2001), Truth and the Absence of Fact, Oxford University Press, Oxford, UK.

• Foucault, Michel (1997), Essential Works of Foucault, 1954–1984, Volume 1, Ethics: Subjectivity and Truth, Paul Rabinow (ed.), Robert Hurley et al. (trans.), The New Press, New York, NY.

• Garfield, Jay L., and Kiteley, Murray (1991), Meaning and Truth: The Essential Readings in Modern Semantics, Paragon House, New York, NY.

• Gupta, Anil (2001), "Truth", in Lou Goble (ed.), The Blackwell Guide to Philosophical Logic, Blackwell Publishers, Oxford, UK.

• Haack, Susan (1993), Evidence and Inquiry: Towards Reconstruction in Epistemology, Blackwell Publishers, Oxford, UK.

• Habermas, Jürgen (1976), "What Is Universal Pragmatics?", 1st published, "Was heißt Universalpragmatik?", Sprachpragmatik und Philosophie, Karl-Otto Apel (ed.), Suhrkamp Verlag, Frankfurt am Main. Reprinted, pp. 1–68 in Jürgen Habermas, Communication and the Evolution of Society, Thomas McCarthy (trans.), Beacon Press, Boston, MA, 1979.

• Habermas, Jürgen (1990), Moral Consciousness and Communicative Action, Christian Lenhardt and Shierry Weber Nicholsen (trans.), Thomas McCarthy (intro.), MIT Press, Cambridge, MA.

• Habermas, Jürgen (2003), Truth and Justification, Barbara Fultner (trans.), MIT Press, Cambridge, MA.

• Horwich, Paul, (1988), Truth, 2nd edition, Oxford University Press, Oxford, UK.

• James, William (1904), A World of Pure Experience.

• James, William (1907), Pragmatism, A New Name for Some Old Ways of Thinking, Popular Lectures on Philosophy, Longmans, Green, and Company, New York, NY.

• James, William (1909), The Meaning of Truth, A Sequel to 'Pragmatism, Longmans, Green, and Company, New York, NY.

• James, William (1912), Essays in Radical Empiricism. Cf. Chapt. 3, "The Thing and its Relations", pp. 92–122.

• Kant, Immanuel (1800), Introduction to Logic. Reprinted, Thomas Kingsmill Abbott (trans.), Dennis Sweet (intro.), Barnes and Noble, New York, NY, 2005.

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• Audi, Robert (ed., 1999), The Cambridge Dictionary of Philosophy, Cambridge University Press, Cambridge, UK, 1995. 2nd edition, 1999. Cited as CDP.

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• Webster's Ninth New Collegiate Dictionary (1983), Frederick C. Mish (ed.), Merriam–Webster Inc., Springfield, MA. Cited as MWC.

See also

• Aletheia
• Asha
• Belief
• Confirmation holism
• contextualism
• Degrees of truth
• Disposition
• Eclecticism
• Half-truth
• Honesty
• Imagination
• Independence
• Inquiry
• Interpretation
• Invariance
• Knowledge
• Liar paradox
• Lie
• Lie-to-children
• Normative science
• Objectivity
• Paradox
• Perspectivism
• Philalethia
• Physical symbol system
• Reality
• Relativism
• Religion
• Slingshot argument
• Statistical independence
• Tautology (logic)
• Tautology (rhetoric)
• Truthiness
• Unity of the proposition
• Veritas

Truth in logic

• Fuzzy logic
• Logic
• Logical value
• Modal logic
• Multi-valued logic
• Principle of bivalence
• Truth conditions
• Truth function
• Truth table
• Criteria of truth

Theories of truth

• Coherentism
• Coherence theory of truth
• Consensus theory of truth
• Correspondence theory of truth
• Deflationary theory of truth
• Epistemic theories of truth
• Indefinability theory of truth
• Pragmatic theory of truth
• Redundancy theory of truth
• Semantic theory of truth

Major theorists

• Aristotle
• Thomas Aquinas
• Augustine of Hippo
• J.L. Austin
• Brand Blanshard
• John Dewey
• Hartry Field
• Gottlob Frege
• Jürgen Habermas
• Martin Heidegger
• Paul Horwich
• William James
• Harold Joachim
• Saul Kripke
• Friedrich Nietzsche
• Charles Sanders Peirce
• Plato
• Karl Popper
• W.V. Quine
• Frank P. Ramsey
• Bertrand Russell
• Socrates
• P.F. Strawson
• Alfred Tarski
• Ludwig Wittgenstein

External links

• An Introduction to Truth by Paul Newall, aimed at beginners.
• Stanford Encyclopedia of Philosophy:
  • Truth
  • Coherence theory of truth
  • Correspondence theory of truth
  • Deflationary theory of truth
  • Identity theory of truth
  • Revision theory of truth
  • Tarski's definition of truth
  • Axiomatic theories of truth
• All the Truths about TRUTH. An alphabetical summary (by author) of views about Truth in philosophy, history, science and religion.

a priori truth, absolute certainty, absolute credibility, absoluteness, accomplished fact, accuracy, actuality, actually, assurance, assuredness, authenticity, axiom, brocard, candor, certain knowledge, certainness, certainty, certitude, correctness, credibility, dead certainty, definiteness, determinacy, determinateness, dictate, dictum, fact, facts, factuality, fait accompli, formula, genuineness, golden rule, gospel, grim reality, historicity, in fact, in truth, ineluctability, inerrability, inerrancy, inevitability, infallibilism, infallibility, law, necessity, nonambiguity, noncontingency, not a dream, objective existence, positiveness, postulate, precision, predestination, predetermination, principium, principle, probatum, proposition, proved fact, reality, really, rightness, rule, self-evident truth, settled principle, sureness, surety, theorem, trueness, truism, truly, truth-loving, truth-speaking, truth-telling, truthfulness, unambiguity, unequivocalness, universal truth, univocity, unmistakableness, veraciousness, veracity, veridicality, verity