Truth has a variety of meanings, such as the state of being in accord with
factA fact is something that has really occurred or is actually the case. The usual test for a statement of fact is verifiability, that is whether it can be shown to correspond to experience. Standard reference works are often used to check facts...
or
realityIn philosophy, reality is the state of things as they actually exist, rather than as they may appear or might be imagined. In a wider definition, reality includes everything that is and has been, whether or not it is observable or comprehensible...
. It can also mean having fidelity to an original or to a standard or ideal. In a common usage, it also means constancy or sincerity in action or character. The
direct oppositeIn logic, the semantic principle of bivalence states that every declarative sentence expressing a proposition has exactly one truth value, either true or false...
of truth is
falsehoodFalse or falsehood may refer to:*False *Lie or falsehood, a type of deception in the form of an untruthful statement*Falsity or falsehood, in law, deceitfulness by one party that results in damage to another...
, which can correspondingly take logical, factual or ethical meanings.
However, language and words are essentially "tools" by which humans convey
informationInformation in its most restricted technical sense is a message or collection of messages that consists of an ordered sequence of symbols, or it is the meaning that can be interpreted from such a message or collection of messages. Information can be recorded or transmitted. It can be recorded as...
to one another. As such, "truth" must have a beneficial use in order to be retained within language. Defining this potency and applicability can be looked upon as "criteria", and the method used to recognize a "truth" is termed a
criterion of truthIn epistemology, criteria of truth are standards and rules used to judge the accuracy of statements and claims. They are tools of verification. Understanding a philosophy's criteria of truth is fundamental to a clear evaluation of that philosophy. This necessity is driven by the varying, and...
. Since there is no single accepted criterion, they can all be considered "
theoriesThe English word theory was derived from a technical term in Ancient Greek philosophy. The word theoria, , meant "a looking at, viewing, beholding", and referring to contemplation or speculation, as opposed to action...
".
Various theories and views of truth continue to be debated among scholars and philosophers. There are differing claims on such questions as what constitutes truth; what things are
truthbearerTruth-bearer is a term used to designate entities that are either true or false and nothing else. The thesis that some things are true while others are false raises the question of the nature of these things. Since there is divergence of opinion on the matter, the term truthbearer is used to be...
s capable of being true or false; how to define and identify truth; the roles that revealed and acquired
knowledgeKnowledge is a familiarity with someone or something unknown, which can include information, facts, descriptions, or skills acquired through experience or education. It can refer to the theoretical or practical understanding of a subject...
play; and whether truth is
subjectiveSubjectivity refers to the subject and his or her perspective, feelings, beliefs, and desires. In philosophy, the term is usually contrasted with objectivity.-Qualia:...
or
objectiveObjectivity is a central philosophical concept which has been variously defined by sources. A proposition is generally considered to be objectively true when its truth conditions are met and are "mind-independent"—that is, not met by the judgment of a conscious entity or subject.- Objectivism...
,
relativeIn philosophy, knowledge relativity is the notion that knowledge can be seen as the relation between a form of representation with up to two sorts of intent – communication and use goals – and with up to three subjects – one who knows, one who is informed, and one who observes and...
or
absoluteThe Absolute is the concept of an unconditional reality which transcends limited, conditional, everyday existence. It is sometimes used as an alternate term for "God" or "the Divine", especially, but by no means exclusively, by those who feel that the term "God" lends itself too easily to...
.
Nomenclature, orthography, and etymology
The English word
truth is from Old English
tríewþ, tréowþ, trýwþ,
Middle EnglishMiddle English is the stage in the history of the English language during the High and Late Middle Ages, or roughly during the four centuries between the late 11th and the late 15th century....
trewþe, cognate to
Old High GermanThe term Old High German refers to the earliest stage of the German language and it conventionally covers the period from around 500 to 1050. Coherent written texts do not appear until the second half of the 8th century, and some treat the period before 750 as 'prehistoric' and date the start of...
triuwida,
Old NorseOld Norse is a North Germanic language that was spoken by inhabitants of Scandinavia and inhabitants of their overseas settlements during the Viking Age, until about 1300....
tryggð. Like
troth, it is a
-th nominalisation of the adjective
true (Old English
tréowe).
The English word
true is from Old English (West Saxon)
(ge)tríewe, tréowe, cognate to
Old SaxonOld Saxon, also known as Old Low German, is the earliest recorded form of Low German, documented from the 8th century until the 12th century, when it evolved into Middle Low German. It was spoken on the north-west coast of Germany and in the Netherlands by Saxon peoples...
(gi)trûui,
Old High GermanThe term Old High German refers to the earliest stage of the German language and it conventionally covers the period from around 500 to 1050. Coherent written texts do not appear until the second half of the 8th century, and some treat the period before 750 as 'prehistoric' and date the start of...
(ga)triuwu (Modern German
treu "faithful"),
Old NorseOld Norse is a North Germanic language that was spoken by inhabitants of Scandinavia and inhabitants of their overseas settlements during the Viking Age, until about 1300....
tryggr,
GothicGothic is an extinct Germanic language that was spoken by the Goths. It is known primarily from the Codex Argenteus, a 6th-century copy of a 4th-century Bible translation, and is the only East Germanic language with a sizable Text corpus...
triggws, all from a Proto-Germanic
*trewwj- "having
good faithIn philosophy, the concept of Good faith—Latin bona fides “good faith”, bona fide “in good faith”—denotes sincere, honest intention or belief, regardless of the outcome of an action; the opposed concepts are bad faith, mala fides and perfidy...
".
Old Norse
, "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
factA fact is something that has really occurred or is actually the case. The usual test for a statement of fact is verifiability, that is whether it can be shown to correspond to experience. Standard reference works are often used to check facts...
or
realityIn philosophy, reality is the state of things as they actually exist, rather than as they may appear or might be imagined. In a wider definition, reality includes everything that is and has been, whether or not it is observable or comprehensible...
", in Anglo-Saxon expressed by
sōþ (Modern English
sooth).
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
verusIn Roman mythology, Veritas, meaning truth, was the goddess of truth, a daughter of Saturn and the mother of Virtue. It was believed that she hid in the bottom of a holy well because she was so elusive. Her image is shown as a young virgin dressed in white...
). Romance languages use terms following the Latin
veritasIn Roman mythology, Veritas, meaning truth, was the goddess of truth, a daughter of Saturn and the mother of Virtue. It was believed that she hid in the bottom of a holy well because she was so elusive. Her image is shown as a young virgin dressed in white...
, while the Greek
aletheia, Russian
pravda and Serbian
istina have separate etymological origins.
Major theories of truth
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 major substantive theories introduced below. Each theory presents perspectives that are widely shared by published scholars. There also have more recently arisen "
deflationaryA deflationary theory of truth is one of a family of theories which all have in common the claim that assertions that predicate truth of a statement do not attribute a property called truth to such a statement.-Redundancy theory:...
" 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.
Substantive theories
Correspondence theory
Correspondence theories state that true beliefs and true statements correspond to the actual state of affairs. This type of theory posits 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 Socrates was a classical Greek Athenian philosopher. Credited as one of the founders of Western philosophy, he is an enigmatic figure known chiefly through the accounts of later classical writers, especially the writings of his students Plato and Xenophon, and the plays of his contemporary ...
,
PlatoPlato , was a Classical Greek philosopher, mathematician, student of Socrates, writer of philosophical dialogues, and founder of the Academy in Athens, the first institution of higher learning in the Western world. Along with his mentor, Socrates, and his student, Aristotle, Plato helped to lay the...
, and
AristotleAristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...
. This class of theories holds that the truth or the falsity of a representation is determined in principle solely by how it relates to "things", by whether it accurately describes those "things". An example of correspondence theory is the statement by the Thirteenth Century philosopher/theologian
Thomas AquinasThomas Aquinas, O.P. , also Thomas of Aquin or Aquino, was an Italian Dominican priest of the Catholic Church, and an immensely influential philosopher and theologian in the tradition of scholasticism, known as Doctor Angelicus, Doctor Communis, or Doctor Universalis...
:
Veritas est adaequatio rei et intellectus ("Truth is the equation [or adequation] of things and intellect"), a statement which Aquinas attributed to the Ninth Century neoplatonist
Isaac IsraeliIsaac Israeli ben Solomon , also known as Isaac Israeli the Elder and Isaac Judaeus, was one of the foremost physicians and philosophers of his time. He is regarded as the father of medieval Jewish Neoplatonism...
. Aquinas also restated the theory as: “A judgment is said to be true when it conforms to the external reality”
Correspondence theory practically operates on the assumption that truth is a matter of accurately copying what was much later called "objective reality" and then representing it in thoughts, words and other symbols. Many modern theorists have stated that this ideal cannot be achieved independently of some analysis of additional factors. For example, language plays a role in that all languages have words that are not easily translatable into another. The
GermanGerman is a West Germanic language, related to and classified alongside English and Dutch. With an estimated 90 – 98 million native speakers, German is one of the world's major languages and is the most widely-spoken first language in the European Union....
word
ZeitgeistZeitgeist is "the spirit of the times" or "the spirit of the age."Zeitgeist is the general cultural, intellectual, ethical, spiritual or political climate within a nation or even specific groups, along with the general ambiance, morals, sociocultural direction, and mood associated with an era.The...
is one such example: one who speaks or understands the language may "know" what it means, but any translation of the word apparently fails to accurately capture its full meaning (this is a problem with many abstract words, especially those derived in agglutinative languages). Thus, some words add an additional parameter to the construction of an accurate
truth predicateIn formal theories of truth, a truth predicate is a fundamental concept based on the sentences of a formal language as interpreted logically. That is, it formalizes the concept that is normally expressed by saying that a sentence, statement, or idea "is true."...
. Among the philosophers who grappled with this problem is
Alfred TarskiAlfred Tarski was a Polish logician and mathematician. Educated at the University of Warsaw and a member of the Lwow-Warsaw School of Logic and the Warsaw School of Mathematics and philosophy, he emigrated to the USA in 1939, and taught and carried out research in mathematics at the University of...
, whose
semantic theoryA semantic theory of truth is a theory of truth in the philosophy of language which holds that truth is a property of sentences.-Origin:The semantic conception of truth, which is related in different ways to both the correspondence and deflationary conceptions, is due to work published by Polish...
is summarized further below in this article.
Proponents of several of the theories below have gone further to assert that there are yet other issues necessary to the analysis, such as interpersonal power struggles, community interactions, personal biases and other factors involved in deciding what is seen as truth.
Coherence theory
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 systemIn formal logic, a formal system consists of a formal language and a set of inference rules, used to derive an expression from one or more other premises that are antecedently supposed or derived . The axioms and rules may be called a deductive apparatus...
s in logic and mathematics. However, formal reasoners are content to contemplate
axiomatically independentIn mathematical logic, independence refers to the unprovability of a sentence from other sentences.A sentence σ is independent of a given first-order theory T if T neither proves nor refutes σ; that is, it is impossible to prove σ from T, and it is also impossible to prove from T that...
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 worldNatural World is the longest-running nature documentary series on British television. 2008 marked the series' 25th anniversary under its present title, though its origins can be traced back to its predecessor The World About Us which began over 40 years ago...
,
empiricalThe word empirical denotes information gained by means of observation or experimentation. Empirical data are data produced by an experiment or observation....
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
rationalistIn epistemology and in its modern sense, rationalism is "any view appealing to reason as a source of knowledge or justification" . In more technical terms, it is a method or a theory "in which the criterion of the truth is not sensory but intellectual and deductive"...
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 positivismLogical positivism is a philosophy that combines empiricism—the idea that observational evidence is indispensable for knowledge—with a version of rationalism incorporating mathematical and logico-linguistic constructs and deductions of epistemology.It may be considered as a type of analytic...
, notably
Otto NeurathOtto Neurath was an Austrian philosopher of science, sociologist, and political economist...
and Carl Hempel.
Constructivist theory
Social constructivismConstructivist epistemology is an epistemological perspective in philosophy about the nature of scientific knowledge. Constructivists maintain that scientific knowledge is constructed by scientists and not discovered from the world. Constructivists claim that the concepts of science are mental...
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,
sexualityHuman sexuality is the awareness of gender differences, and the capacity to have erotic experiences and responses. Human sexuality can also be described as the way someone is sexually attracted to another person whether it is to opposite sexes , to the same sex , to either sexes , or not being...
, and
genderGender is a range of characteristics used to distinguish between males and females, particularly in the cases of men and women and the masculine and feminine attributes assigned to them. Depending on the context, the discriminating characteristics vary from sex to social role to gender identity...
are socially constructed.
Giambattista VicoGiovanni Battista ' Vico or Vigo was an Italian political philosopher, rhetorician, historian, and jurist....
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 and Marx were among the other early proponents of the premise that truth is, or can be, socially constructed. Marx, like many critical theorists who followed, did not reject the existence of objective truth but rather distinguished between true knowledge and knowledge that has been distorted through power or ideology. For Marx scientific and true knowledge is 'in accordance with the dialectical understanding of history' and ideological knowledge 'an epiphenomenal expression of the relation of material forces in a given economic arrangement'.
Consensus theory
Consensus theoryA consensus theory of truth is any theory of truth that refers to a concept of consensus as a part of its concept of truth.-Consensus gentium:...
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
subsetIn mathematics, especially in set theory, a set A is a subset of a set B if A is "contained" inside B. A and B may coincide. The relationship of one set being a subset of another is called inclusion or sometimes containment...
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 HabermasJürgen Habermas is a German sociologist and philosopher in the tradition of critical theory and pragmatism. He is perhaps best known for his theory on the concepts of 'communicative rationality' and the 'public sphere'...
. Habermas maintains that truth is what would be agreed upon in an
ideal speech situationIn the earlier philosophy of Jürgen Habermas it is argued that an ideal speech situation is found within communication between individuals when their speech is governed by basic, but required and implied, rules...
. Among the current strong critics of consensus theory is the philosopher
Nicholas RescherNicholas Rescher is an American philosopher at the University of Pittsburgh. In a productive research career extending over six decades, Rescher has established himself as a systematic philosopher of the old style and author of a system of pragmatic idealism which weaves together threads of...
.
Pragmatic theory
The three most influential forms of the
pragmatic theory of truth were introduced around the turn of the 20th century by Charles Sanders Peirce,
William JamesWilliam James was a pioneering American psychologist and philosopher who was trained as a physician. He wrote influential books on the young science of psychology, educational psychology, psychology of religious experience and mysticism, and on the philosophy of pragmatism...
, and
John DeweyJohn Dewey was an American philosopher, psychologist and educational reformer whose ideas have been influential in education and social reform. Dewey was an important early developer of the philosophy of pragmatism and one of the founders of functional psychology...
. 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
fallibilismFallibilism is the philosophical principle that human beings could be wrong about their beliefs, expectations, or their understanding of the world...
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 relationA sign relation is the basic construct in the theory of signs, also known as semeiotic or semiotics, as developed by Charles Sanders Peirce.-Anthesis:...
, 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'sWilliam James was a pioneering American psychologist and philosopher who was trained as a physician. He wrote influential books on the young science of psychology, educational psychology, psychology of religious experience and mysticism, and on the philosophy of pragmatism...
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 DeweyJohn Dewey was an American philosopher, psychologist and educational reformer whose ideas have been influential in education and social reform. Dewey was an important early developer of the philosophy of pragmatism and one of the founders of functional psychology...
, less broadly than James but more broadly than Peirce, held that
inquiryAn inquiry is any process that has the aim of augmenting knowledge, resolving doubt, or solving a problem. A theory of inquiry is an account of the various types of inquiry and a treatment of the ways that each type of inquiry achieves its aim.-Deduction:...
, 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.
Though not widely touted nor publicized, a new variation of the pragmatic theory was defined and wielded successfully from the 20th century forward. Defined and named by William Hocking, this variation is known as "negative pragmatism". Essentially, what works may or may not be true, but what fails cannot be true because the truth always works.
Richard FeynmanRichard Phillips Feynman was an American physicist known for his work in the path integral formulation of quantum mechanics, the theory of quantum electrodynamics and the physics of the superfluidity of supercooled liquid helium, as well as in particle physics...
also ascribed to it: "We never are definitely right, we can only be sure we are wrong." This approach incorporates many of the ideas from Peirce, James, and Dewey. For Peirce, the idea of "... endless investigation would tend to bring about scientific belief ..." fits negative pragmatism in that a negative pragmatist would never stop testing. As Feynman noted, an idea or theory "... could never be proved right, because tomorrow's experiment might succeed in proving wrong what you thought was right." Similarly, James and Dewey's ideas also ascribe to repeated testing which is "self-corrective" over time.
Pragmatism and negative pragmatism are also closely aligned with the
coherence theory of truthCoherence theory of truth regards truth as coherence with some specified set of sentences, propositions or beliefs. There is no single coherence theory of truth, but rather an assortment of perspectives that are commonly collected under this title...
in that any testing should not be isolated but rather incorporate knowledge from all human endeavors and experience. The universe is a whole and integrated system, and testing should recognize and account for its diversity. As Feynman said, "... if it disagrees with experiment, it is wrong."
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." Once we have identified the truth predicate's formal features and utility, deflationists argue, we have said all there is to be said about truth. Among the theoretical concerns of these views is to explain away those special cases where it
does appear that the concept of truth has peculiar and interesting properties. (See, e.g., Semantic paradoxes, and below.)
In addition to highlighting such formal aspects of the predicate "is true", some deflationists point out that the concept enables us to express things that might otherwise require infinitely long sentences. For example, one cannot express confidence in Michael's accuracy by asserting the endless sentence:
- Michael says, 'snow is white' and snow is white, or he says 'roses are red' and roses are red or he says ... etc.
This assertion can also be succinctly expressed by saying:
What Michael says is true.
Performative theory of truth
Attributed to
P. F. StrawsonSir Peter Frederick Strawson FBA was an English philosopher. He was the Waynflete Professor of Metaphysical Philosophy at the University of Oxford from 1968 to 1987. Before that he was appointed as a college lecturer at University College, Oxford in 1947 and became a tutorial fellow the...
is the performative theory of truth which holds that to say "'Snow is white' is true" is to perform the
speech actSpeech Act is a technical term in linguistics and the philosophy of language. The contemporary use of the term goes back to John L. Austin's doctrine of locutionary, illocutionary, and perlocutionary acts...
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, but actually doing so (perhaps the most thorough analysis of such "illocutionary acts" is
J. L. AustinJohn Langshaw Austin was a British philosopher of language, born in Lancaster and educated at Shrewsbury School and Balliol College, Oxford University. Austin is widely associated with the concept of the speech act and the idea that speech is itself a form of action...
, "How to Do Things With Words").
Strawson holds that a similar analysis is applicable to all speech acts, not just illocutionary ones: "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 truthAccording to the redundancy theory of truth, or the disquotational theory of truth, asserting that a statement is true is completely equivalent to asserting the statement itself. For example, asserting the sentence " 'Snow is white' is true" is equivalent to asserting the sentence "Snow is...
, 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. RamseyFrank Plumpton Ramsey was a British mathematician who, in addition to mathematics, made significant and precocious contributions in philosophy and economics before his death at the age of 26...
, who held that the use of words like
fact and
truth was nothing but a
roundaboutIn linguistics, periphrasis is a device by which a grammatical category or grammatical relationship is expressed by a free morpheme , instead of being shown by inflection or derivation...
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. A version of this theory was defended by
C. J. F. WilliamsChristopher John Fardo Williams was a British philosopher. His areas of interest were philosophical logic, on which topic he did most of his original work, and Ancient philosophy, as an editor and translator.-Life:...
in his book
What is Truth?. Yet another version of deflationism is the prosentential theory of truth, first developed by Dorothy Grover, Joseph Camp, and
Nuel BelnapNuel D. Belnap, Jr. is an American logician and philosopher who has made many important contributions to the philosophy of logic, temporal logic, and structural proof theory. He has taught at the University of Pittsburgh since 1961; before that he was at Yale University. His best known work is...
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."
Deflationary principles do not apply to representations that are not analogous to sentences, and also do not apply to many other things that are commonly judged to be true or otherwise. Consider the analogy between the sentence "Snow is white" and the character named Snow White, both of which can be true in some sense. To a minimalist,
saying "Snow is white is true" is the same as saying "Snow is white," but to say "Snow White is true" is
not the same as saying "Snow White."
Pluralist theories
Several of the major theories of truth hold that there is a particular property the having of which makes a belief or proposition true. Pluralist theories of truth assert that there may be more than one property that makes propositions true: ethical propositions might be true by virtue of coherence. Propositions about the physical world might be true by corresponding to the objects and properties they are about.
Some of the pragmatic theories, such as those by Charles Peirce and
William JamesWilliam James was a pioneering American psychologist and philosopher who was trained as a physician. He wrote influential books on the young science of psychology, educational psychology, psychology of religious experience and mysticism, and on the philosophy of pragmatism...
, included aspects of correspondence, coherence and constructivist theories.
Crispin WrightCrispin Wright is a British philosopher, who has written on neo-Fregean philosophy of mathematics, Wittgenstein's later philosophy, and on issues related to truth, realism, cognitivism, skepticism, knowledge, and objectivity....
argued in his 1992 book
Truth and Objectivity that any predicate which satisfied certain platitudes about truth qualified as a truth predicate. In some discourses, Wright argued, the role of the truth predicate might be played by the notion of superassertibility.
Michael LynchMichael Lynch is Professor of Philosophy at the University of Connecticut and Associate Fellow of the Arché Centre for Logic, Language, Metaphysics and Epistemology at the University of St. Andrews, Scotland. He is the author of Truth in Context and True to Life Lynch is most well known for his...
, in a 2009 book
Truth as One and Many, argued that we should see truth as a functional property capable of being multiply manifested in distinct properties like correspondence or coherence.
Most believed theories
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) 44.9% of respondents accept or lean towards correspondence theories, 20.7% accept or lean towards deflationary theories and 13.8% epistemic theories.
Truth in logic
LogicIn philosophy, Logic is the formal systematic study of the principles of valid inference and correct reasoning. Logic is used in most intellectual activities, but is studied primarily in the disciplines of philosophy, mathematics, semantics, and computer science...
is concerned with the patterns in
reasonReason is a term that refers to the capacity human beings have to make sense of things, to establish and verify facts, and to change or justify practices, institutions, and beliefs. It is closely associated with such characteristically human activities as philosophy, science, language, ...
that can help tell us if a
propositionIn logic and philosophy, the term proposition refers to either the "content" or "meaning" of a meaningful declarative sentence or the pattern of symbols, marks, or sounds that make up a meaningful declarative sentence...
is true or not. However, logic does not deal with truth in the absolute sense, as for instance a
metaphysicianMetaphysics is a branch of philosophy concerned with explaining the fundamental nature of being and the world, although the term is not easily defined. Traditionally, metaphysics attempts to answer two basic questions in the broadest possible terms:...
does. Logicians use
formal languageA formal language is a set of words—that is, finite strings of letters, symbols, or tokens that are defined in the language. The set from which these letters are taken is the alphabet over which the language is defined. A formal language is often defined by means of a formal grammar...
s to express the truths which they are concerned with, and as such there is only truth under some
interpretationAn interpretation is an assignment of meaning to the symbols of a formal language. Many formal languages used in mathematics, logic, and theoretical computer science are defined in solely syntactic terms, and as such do not have any meaning until they are given some interpretation...
or truth within some logical system.
A logical truth (also called an analytic truth or a necessary truth) is a statement which is true in all possible worlds or under all possible interpretations, as contrasted to a
factA fact is something that has really occurred or is actually the case. The usual test for a statement of fact is verifiability, that is whether it can be shown to correspond to experience. Standard reference works are often used to check facts...
(also called a
synthetic claim or a
contingency) which is only true in this world as it has historically unfolded. A proposition such as “If p and q, then p.” is considered to be logical truth because it is true because of the meaning of the
symbolsFor other uses see Symbol In logic, symbols build literal utility to illustrate ideas. A symbol is an abstraction, tokens of which may be marks or a configuration of marks which form a particular pattern...
and
wordsIn mathematical logic, a well-formed formula, shortly wff, often simply formula, is a word which is part of a formal language...
in it and not because of any facts of any particular world. They are such that they could not be untrue.
Truth in mathematics
There are two main approaches to truth in mathematics. They are the
model theory of truthIn mathematics, model theory is the study of mathematical structures using tools from mathematical logic....
and the
proof theory of truthProof theory is a branch of mathematical logic that represents proofs as formal mathematical objects, facilitating their analysis by mathematical techniques. Proofs are typically presented as inductively-defined data structures such as plain lists, boxed lists, or trees, which are constructed...
.
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 tableA truth table is a mathematical table used in logic—specifically in connection with Boolean algebra, boolean functions, and propositional calculus—to compute the functional values of logical expressions on each of their functional arguments, that is, on each combination of values taken by their...
s.
In addition, from at least the time of
Hilbert's programIn mathematics, Hilbert's program, formulated by German mathematician David Hilbert, was a proposed solution to the foundational crisis of mathematics, when early attempts to clarify the foundations of mathematics were found to suffer from paradoxes and inconsistencies...
at the turn of the twentieth century to the proof of
Gödel's theoremGödel's theorem may refer to:*Gödel's incompleteness theorems*Gödel's completeness theorem*Gödel's speedup 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 GödelKurt Friedrich Gödel was an Austrian logician, mathematician and philosopher. Later in his life he emigrated to the United States to escape the effects of World War II. One of the most significant logicians of all time, Gödel made an immense impact upon scientific and philosophical thinking in the...
,
Alan TuringAlan Mathison Turing, OBE, FRS , was an English mathematician, logician, cryptanalyst, and computer scientist. He was highly influential in the development of computer science, providing a formalisation of the concepts of "algorithm" and "computation" with the Turing machine, which played a...
, 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 problemsHilbert's problems form a list of twenty-three problems in mathematics published by German mathematician David Hilbert in 1900. The problems were all unsolved at the time, and several of them were very influential for 20th century mathematics...
. 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 hypothesisIn mathematics, the continuum hypothesis is a hypothesis, advanced by Georg Cantor in 1874, about the possible sizes of infinite sets. It states:Establishing the truth or falsehood of the continuum hypothesis is the first of Hilbert's 23 problems presented in the year 1900...
. Gödel and
Paul CohenPaul Joseph Cohen was an American mathematician best known for his proof of the independence of the continuum hypothesis and the axiom of choice from Zermelo–Fraenkel set theory, the most widely accepted axiomatization of set theory.-Early years:Cohen was born in Long Branch, New Jersey, into a...
showed that this hypothesis cannot be proved or disproved using the standard
axiomIn traditional logic, an axiom or postulate is a proposition that is not proven or demonstrated but considered either to be self-evident or to define and delimit the realm of analysis. In other words, an axiom is a logical statement that is assumed to be true...
s of
set theorySet theory is the branch of mathematics that studies sets, which are collections of objects. Although any type of object can be collected into a set, set theory is applied most often to objects that are relevant to mathematics...
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 truthA semantic theory of truth is a theory of truth in the philosophy of language which holds that truth is a property of sentences.-Origin:The semantic conception of truth, which is related in different ways to both the correspondence and deflationary conceptions, is due to work published by Polish...
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 TarskiAlfred Tarski was a Polish logician and mathematician. Educated at the University of Warsaw and a member of the Lwow-Warsaw School of Logic and the Warsaw School of Mathematics and philosophy, he emigrated to the USA in 1939, and taught and carried out research in mathematics at the University of...
developed the theory for formal languages (such as
formal logicClassical or traditional system of determining the validity or invalidity of a conclusion deduced from two or more statements...
). 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 paradoxIn philosophy and logic, the liar paradox or liar's paradox , is the statement "this sentence is false"...
. 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 DavidsonDonald Herbert Davidson was an American philosopher born in Springfield, Massachusetts, who served as Slusser Professor of Philosophy at the University of California, Berkeley from 1981 to 2003 after having also held teaching appointments at Stanford University, Rockefeller University, Princeton...
used it as the foundation of his
truth-conditional semanticsTruth-conditional semantics is an approach to semantics of natural language that sees the meaning of assertions as being the same as, or reducible to, their truth conditions...
and linked it to
radical interpretationRadical interpretation is interpretation of a speaker, including attributing beliefs and desires to them and meanings to their words, from scratch—that is, without relying on translators, dictionaries, or specific prior knowledge of their mental states. The term was introduced by American...
in a form of
coherentismThere are two distinct types of coherentism. One refers to the coherence theory of truth. The other refers to the coherence theory of justification. The coherentist theory of justification characterizes epistemic justification as a property of a belief only if that belief is a member of a coherent...
.
Bertrand RussellBertrand Arthur William Russell, 3rd Earl Russell, OM, FRS was a British philosopher, logician, mathematician, historian, and social critic. At various points in his life he considered himself a liberal, a socialist, and a pacifist, but he also admitted that he had never been any of these things...
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 paradoxIn the foundations of mathematics, Russell's paradox , discovered by Bertrand Russell in 1901, showed that the naive set theory created by Georg Cantor leads to a contradiction...
. Russell and
WhiteheadAlfred North Whitehead, OM FRS was an English mathematician who became a philosopher. He wrote on algebra, logic, foundations of mathematics, philosophy of science, physics, metaphysics, and education...
attempted to solve these problems in
Principia MathematicaThe Principia Mathematica is a three-volume work on the foundations of mathematics, written by Alfred North Whitehead and Bertrand Russell and published in 1910, 1912, and 1913...
by putting statements into a hierarchy of
typesIn mathematics, logic and computer science, type theory is any of several formal systems that can serve as alternatives to naive set theory, or the study of such formalisms in general...
, 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 systemA type system associates a type with each computed value. By examining the flow of these values, a type system attempts to ensure or prove that no type errors can occur...
s that have yet to be resolved to this day.
Kripke's theory of truth
Saul KripkeSaul Aaron Kripke is an American philosopher and logician. He is a professor emeritus at Princeton and teaches as a Distinguished Professor of Philosophy at the CUNY Graduate Center...
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 bivalenceIn logic, the semantic principle of bivalence states that every declarative sentence expressing a proposition has exactly one truth value, either true or false...
: 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 views
Ancient history
The ancient
GreekGreek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
origins of the words "true" and "truth" have some consistent definitions throughout great spans of history that were often associated with topics of
logicIn philosophy, Logic is the formal systematic study of the principles of valid inference and correct reasoning. Logic is used in most intellectual activities, but is studied primarily in the disciplines of philosophy, mathematics, semantics, and computer science...
,
geometryGeometry arose as the field of knowledge dealing with spatial relationships. Geometry was one of the two fields of pre-modern mathematics, the other being the study of numbers ....
,
mathematicsMathematics is the study of quantity, space, structure, and change. Mathematicians seek out patterns and formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proofs, which are arguments sufficient to convince other mathematicians of their validity...
,
deductionDeductive reasoning, also called deductive logic, is reasoning which constructs or evaluates deductive arguments. Deductive arguments are attempts to show that a conclusion necessarily follows from a set of premises or hypothesis...
,
inductionInductive reasoning, also known as induction or inductive logic, is a kind of reasoning that constructs or evaluates propositions that are abstractions of observations. It is commonly construed as a form of reasoning that makes generalizations based on individual instances...
, and
natural philosophyNatural philosophy or the philosophy of nature , is a term applied to the study of nature and the physical universe that was dominant before the development of modern science...
.
Socrates' Socrates was a classical Greek Athenian philosopher. Credited as one of the founders of Western philosophy, he is an enigmatic figure known chiefly through the accounts of later classical writers, especially the writings of his students Plato and Xenophon, and the plays of his contemporary ...
,
Plato'sPlato , was a Classical Greek philosopher, mathematician, student of Socrates, writer of philosophical dialogues, and founder of the Academy in Athens, the first institution of higher learning in the Western world. Along with his mentor, Socrates, and his student, Aristotle, Plato helped to lay the...
and
Aristotle'sAristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...
ideas about truth are commonly seen as consistent with correspondence theory. In his
MetaphysicsMetaphysics is one of the principal works of Aristotle and the first major work of the branch of philosophy with the same name. The principal subject is "being qua being", or being understood as being. It examines what can be asserted about anything that exists just because of its existence and...
, 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 PhilosophyThe Stanford Encyclopedia of Philosophy is a freely-accessible online encyclopedia of philosophy maintained by Stanford University. Each entry is written and maintained by an expert in the field, including professors from over 65 academic institutions worldwide...
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.
Very similar statements can also be found in Plato (Cratylus 385b2, Sophist 263b).
In Hinduism, Truth is defined as "unchangeable", "that which has no distortion", "that which is beyond distinctions of time, space, and person", "that which pervades the universe in all its constancy". Human body, therefore is not completely true as it changes with time, for example. There are many references, properties and explanations of truth by Hindu sages that explain varied facets of truth, such as "Satyam eva jayate"(Truth alone wins), "Satyam muktaye" (Truth liberates), Satya' is 'Parahit'artham' va'unmanaso yatha'rthatvam' satyam (Satya is the benevolent use of words and the mind for the welfare of others or in other words responsibilities is truth too), "When one is firmly established in speaking truth, the fruits of action become subservient to him ( patanjali yogasutras, sutra number 2.36 ), "The face of truth is covered by a golden bowl.
Unveil it, O Pusan (Sun), so that I who have truth as my duty (satyadharma) may see it!" (Brhadaranyaka V 15 1-4 and the brief IIsa Upanisad 15-18), Truth is superior to silence(Manusmriti), etc. Combined with other words, satya acts as modifier, like "
ultra" or "
highest," or more literally "
truest," connoting
purity and excellence. For example, satyaloka is the "highest heaven' and Satya Yuga is the "golden age" or best of the four cyclical cosmic ages in Hinduism, and so on.
Avicenna
In
early Islamic philosophyEarly Islamic philosophy or classical Islamic philosophy is a period of intense philosophical development beginning in the 2nd century AH of the Islamic calendar and lasting until the 6th century AH...
,
AvicennaAbū ʿAlī al-Ḥusayn ibn ʿAbd Allāh ibn Sīnā , commonly known as Ibn Sīnā or by his Latinized name Avicenna, was a Persian polymath, who wrote almost 450 treatises on a wide range of subjects, of which around 240 have survived...
(Ibn Sina) defined truth in his Metaphysics of Healing, Book I, Chapter 8, as:
AvicennaAbū ʿAlī al-Ḥusayn ibn ʿAbd Allāh ibn Sīnā , commonly known as Ibn Sīnā or by his Latinized name Avicenna, was a Persian polymath, who wrote almost 450 treatises on a wide range of subjects, of which around 240 have survived...
elaborated on his definition of truth in his
MetaphysicsMetaphysics is a branch of philosophy concerned with explaining the fundamental nature of being and the world, although the term is not easily defined. Traditionally, metaphysics attempts to answer two basic questions in the broadest possible terms:...
Book Eight, Chapter 6:
However, this definition is merely a translation of the Latin translation from the Middle Ages. A modern translation of the original Arabic text states:
Aquinas
Reevaluating Avicenna, and also Augustine and Aristotle,
Thomas AquinasThomas Aquinas, O.P. , also Thomas of Aquin or Aquino, was an Italian Dominican priest of the Catholic Church, and an immensely influential philosopher and theologian in the tradition of scholasticism, known as Doctor Angelicus, Doctor Communis, or Doctor Universalis...
stated in his
Disputed Questions on Truth:
Thus, for Aquinas, 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:
Aquinas also said that real things participate in the act of being of the
Creator GodGod is the English name given to a singular being in theistic and deistic religions who is either the sole deity in monotheism, or a single deity in polytheism....
who is Subsistent Being, Intelligence, and Truth. Thus, these beings possess the light of intelligibility and are knowable. These things (beings;
realityIn philosophy, reality is the state of things as they actually exist, rather than as they may appear or might be imagined. In a wider definition, reality includes everything that is and has been, whether or not it is observable or comprehensible...
) are the foundation of the truth that is found in the human mind, when it acquires knowledge of things, first through the
senseSenses are physiological capacities of organisms that provide inputs for perception. The senses and their operation, classification, and theory are overlapping topics studied by a variety of fields, most notably neuroscience, cognitive psychology , and philosophy of perception...
s, then through the
understandingUnderstanding is a psychological process related to an abstract or physical object, such as a person, situation, or message whereby one is able to think about it and use concepts to deal adequately with that object....
and the
judgementJudgment is the evaluation of evidence in the making of a decision. The term has three distinct uses:* Informal - Opinions expressed as facts....
done by
reasonReason is a term that refers to the capacity human beings have to make sense of things, to establish and verify facts, and to change or justify practices, institutions, and beliefs. It is closely associated with such characteristically human activities as philosophy, science, language, ...
. For Aquinas, human
intelligenceIntelligence has been defined in different ways, including the abilities for abstract thought, understanding, communication, reasoning, learning, planning, emotional intelligence and problem solving....
("intus", within and "legere", to read) has the capability to reach the
essenceIn philosophy, essence is the attribute or set of attributes that make an object or substance what it fundamentally is, and which it has by necessity, and without which it loses its identity. Essence is contrasted with accident: a property that the object or substance has contingently, without...
and
existenceIn common usage, existence is the world we are aware of through our senses, and that persists independently without them. In academic philosophy the word has a more specialized meaning, being contrasted with essence, which specifies different forms of existence as well as different identity...
of things because it has a non-material,
spiritualSpirituality can refer to an ultimate or an alleged immaterial reality; an inner path enabling a person to discover the essence of his/her being; or the “deepest values and meanings by which people live.” Spiritual practices, including meditation, prayer and contemplation, are intended to develop...
element, although some moral, educational, and other elements might interfere with its capability.
Kant
Immanuel KantImmanuel Kant was a German philosopher from Königsberg , researching, lecturing and writing on philosophy and anthropology at the end of the 18th Century Enlightenment....
endorses a definition of truth along the lines of the correspondence theory of truth. Kant writes in the
Critique of Pure ReasonThe Critique of Pure Reason by Immanuel Kant, first published in 1781, second edition 1787, is considered one of the most influential works in the history of philosophy. Also referred to as Kant's "first critique," it was followed by the Critique of Practical Reason and the Critique of Judgement...
: "The nominal definition of truth, namely that it is the agreement of cognition with its object, is here granted and presupposed". However, Kant denies that this correspondence definition of truth provides us with a test or criterion to establish which judgements are true. Kant states in his logic lectures:
Truth, it is said, consists in the agreement of cognition with its object. In consequence of this mere nominal definition, my cognition, to count as true, is supposed to agree with its object. Now I can compare the object with my cognition, however, only by cognizing it. Hence my cognition is supposed to confirm itself, which is far short of being sufficient for truth. For since the object is outside me, the cognition in me, all I can ever pass judgement on is whether my cognition of the object agrees with my cognition of the object.
The ancients called such a circle in explanation a diallelon. And actually the logicians were always reproached with this mistake by the sceptics, who observed that with this definition of truth it is just as when someone makes a statement before a court and in doing so appeals to a witness with whom no one is acquainted, but who wants to establish his credibility by maintaining that the one who called him as witness is an honest man. The accusation was grounded, too. Only the solution of the indicated problem is impossible without qualification and for every man.
This passage makes use of his distinction between nominal and real definitions. A nominal definition explains the meaning of a linguistic expression. A real definition describes the essence of certain objects and enable us to determine whether any given item falls within the definition. Kant holds that the definition of truth is merely nominal and, therefore, we cannot employ it to establish which judgements are true. According to Kant, the ancient skeptics criticized the logicians for holding that, by means of a merely nominal definition of truth, they can establish which judgements are true. They were trying to do something that is "impossible without qualification and for every man".
Hegel
Hegel distanced his philosophy from psychology by presenting truth as being an external self–moving object instead of being related to inner, subjective thoughts. Hegel's truth is analogous to the
mechanicsMechanics is the branch of physics concerned with the behavior of physical bodies when subjected to forces or displacements, and the subsequent effects of the bodies on their environment....
of a material body in motion under the influence of its own inner force. "Truth is its own self–movement within itself." Teleological truth moves itself in the three–step form of
dialectical triplicityDialectic is a method of argument for resolving disagreement that has been central to Indic and European philosophy since antiquity. The word dialectic originated in Ancient Greece, and was made popular by Plato in the Socratic dialogues...
toward the final goal of perfect, final, absolute truth. For Hegel, the progression of philosophical truth is a resolution of past oppositions into increasingly more accurate approximations to absolute truth.
ChalybäusHeinrich Moritz Chalybäus was a German philosopher best known for his exegetical work on philosophy, such as his characterisation of Hegel's dialectic as positing a triad of thesis-antithesis-synthesis....
used the terms "
thesisThe triad thesis, antithesis, synthesis is often used to describe the thought of German philosopher Georg Wilhelm Friedrich Hegel. Hegel never used the term himself, and almost all of his biographers have been eager to discredit it....
", "
antithesisThe triad thesis, antithesis, synthesis is often used to describe the thought of German philosopher Georg Wilhelm Friedrich Hegel. Hegel never used the term himself, and almost all of his biographers have been eager to discredit it....
", and "
synthesisThe triad thesis, antithesis, synthesis is often used to describe the thought of German philosopher Georg Wilhelm Friedrich Hegel. Hegel never used the term himself, and almost all of his biographers have been eager to discredit it....
" to describe Hegel's dialectical triplicity. The "thesis" consists of an incomplete historical movement. To resolve the incompletion, an "antithesis" occurs which opposes the "thesis." In turn, the "synthesis" appears when the "thesis" and "antithesis" become
reconciledSublation may refer to:*Sublation, a translation of the German term aufheben*Ritual purification, the purification or exaltation of matter by its negation or redirection...
and a higher level of truth is obtained. This "synthesis" thereby becomes a "thesis," which will again necessitate an "antithesis," requiring a new "synthesis" until a final state is reached as the result of reason's historical movement. History is the
Absolute SpiritThe Absolute is the concept of an unconditional reality which transcends limited, conditional, everyday existence. It is sometimes used as an alternate term for "God" or "the Divine", especially, but by no means exclusively, by those who feel that the term "God" lends itself too easily to...
moving toward a goal. This historical progression will finally conclude itself when the Absolute Spirit understands its own infinite self at the very end of history. Absolute Spirit will then be the complete expression of an infinite
GodGod is the English name given to a singular being in theistic and deistic religions who is either the sole deity in monotheism, or a single deity in polytheism....
.
Schopenhauer
For
SchopenhauerArthur Schopenhauer was a German philosopher known for his pessimism and philosophical clarity. At age 25, he published his doctoral dissertation, On the Fourfold Root of the Principle of Sufficient Reason, which examined the four separate manifestations of reason in the phenomenal...
, a
judgmentA judgment , in a legal context, is synonymous with the formal decision made by a court following a lawsuit. At the same time the court may also make a range of court orders, such as imposing a sentence upon a guilty defendant in a criminal matter, or providing a remedy for the plaintiff in a civil...
is a combination or separation of two or more
conceptThe word concept is used in ordinary language as well as in almost all academic disciplines. Particularly in philosophy, psychology and cognitive sciences the term is much used and much discussed. WordNet defines concept: "conception, construct ". However, the meaning of the term concept is much...
s. If a judgment is to be an expression of
knowledgeKnowledge is a familiarity with someone or something unknown, which can include information, facts, descriptions, or skills acquired through experience or education. It can refer to the theoretical or practical understanding of a subject...
, it must have a
sufficient reasonThe principle of sufficient reason states that anything that happens does so for a reason: no state of affairs can obtain, and no statement can be true unless there is sufficient reason why it should not be otherwise...
or ground by which the judgment could be called true.
Truth is the reference of a judgment to something different from itself which is its sufficient reason (ground). Judgments can have material, formal, transcendental, or metalogical truth. A judgment has
material truth if its concepts are based on intuitive perceptions that are generated from sensations. If a judgment has its reason (ground) in another judgment, its truth is called logical or
formal. If a judgment, of, for example, pure mathematics or pure science, is based on the forms (space, time, causality) of intuitive, empirical knowledge, then the judgment has
transcendental truth.
Kierkegaard
When
Søren KierkegaardSøren Aabye Kierkegaard was a Danish Christian philosopher, theologian and religious author. He was a critic of idealist intellectuals and philosophers of his time, such as Georg Wilhelm Friedrich Hegel, Friedrich Wilhelm Joseph Schelling and Karl Wilhelm Friedrich Schlegel...
, as his character
Johannes Climacus, ends his writings:
My thesis was, subjectivity, heartfelt is the truth, he does not advocate for
subjectivismSubjectivism is a philosophical tenet that accords primacy to subjective experience as fundamental of all measure and law. In extreme forms like Solipsism, it may hold that the nature and existence of every object depends solely on someone's subjective awareness of it...
in its extreme form (the theory that something is true simply because one believes it to be so), but rather that the objective approach to matters of personal truth cannot shed any light upon that which is most essential to a person's life. Objective truths are concerned with the facts of a person's being, while subjective truths are concerned with a person's way of being. Kierkegaard agrees that objective truths for the study of subjects like mathematics, science, and history are relevant and necessary, but argues that objective truths do not shed any light on a person's inner relationship to existence. At best, these truths can only provide a severely narrowed perspective that has little to do with one's actual experience of life.
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 NietzscheFriedrich Wilhelm Nietzsche was a 19th-century German philosopher, poet, composer and classical philologist...
believed the search for truth or 'the will to truth' was a consequence of the
will to powerThe will to power is widely seen as a prominent concept in the philosophy of Friedrich Nietzsche. The will to power describes what Nietzsche may have believed to be the main driving force in man; achievement, ambition, the striving to reach the highest possible position in life; these are all...
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 EvilBeyond Good and Evil is a book by the philosopher Friedrich Nietzsche, first published in 1886.It takes up and expands on the ideas of his previous work, Thus Spoke Zarathustra, but approached from a more critical, polemical direction....
, "
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.
Whitehead
Alfred North WhiteheadAlfred North Whitehead, OM FRS was an English mathematician who became a philosopher. He wrote on algebra, logic, foundations of mathematics, philosophy of science, physics, metaphysics, and education...
, 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 FrommErich Seligmann Fromm was a Jewish German-American social psychologist, psychoanalyst, sociologist, humanistic philosopher, and democratic socialist. He was associated with what became known as the Frankfurt School of critical theory.-Life:Erich Fromm was born on March 23, 1900, at Frankfurt am...
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 FoucaultMichel Foucault , born Paul-Michel Foucault , was a French philosopher, social theorist and historian of ideas...
, 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
epistemeEpisteme, as distinguished from techne, is etymologically derived from the Greek word ἐπιστήμη for knowledge or science, which comes from the verb ἐπίσταμαι, "to know".- The Concept of an "Episteme" in Michel Foucault :...
throughout history.
Baudrillard
Jean BaudrillardJean Baudrillard was a French sociologist, philosopher, cultural theorist, political commentator, and photographer. His work is frequently associated with postmodernism and post-structuralism.-Life:...
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
iconoclastIconoclasm is the deliberate destruction of religious icons and other symbols or monuments, usually with religious or political motives. It is a frequent component of major political or religious changes...
s 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
Simulacrum , from the Latin simulacrum which means "likeness, similarity", was first recorded in the English language in the late 16th century, used to describe a representation, such as a statue or a painting, especially of a god...
is never that which conceals the truth—it is the truth which conceals that there is none. The simulacrum is true.
- —Ecclesiastes
Some examples of simulacra that Baudrillard cited were: that prisons simulate the "truth" that society is free; scandals (e.g.,
WatergateThe Watergate scandal was a political scandal during the 1970s in the United States resulting from the break-in of the Democratic National Committee headquarters at the Watergate office complex in Washington, D.C., and the Nixon administration's attempted cover-up of its involvement...
) 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 theory. For a less extreme example, consider how movies usually end with the bad being punished, humiliated, or otherwise failing, thus affirming for viewers the concept that the good end happily and the bad unhappily, a narrative which implies that the status quo and institutionalised power structures are largely legitimate.
Ratzinger
Philosopher and theologian Joseph Ratzinger, before his election as Benedict XVI, commented upon the relationship of truth with
toleranceToleration is "the practice of deliberately allowing or permitting a thing of which one disapproves. One can meaningfully speak of tolerating, ie of allowing or permitting, only if one is in a position to disallow”. It has also been defined as "to bear or endure" or "to nourish, sustain or preserve"...
,
conscienceConscience is an aptitude, faculty, intuition or judgment of the intellect that distinguishes right from wrong. Moral judgement may derive from values or norms...
,
freedomLiberty is a moral and political principle, or Right, that identifies the condition in which human beings are able to govern themselves, to behave according to their own free will, and take responsibility for their actions...
, and
religionReligion is a collection of cultural systems, belief systems, and worldviews that establishes symbols that relate humanity to spirituality and, sometimes, to moral values. Many religions have narratives, symbols, traditions and sacred histories that are intended to give meaning to life or to...
. For him, "beyond all particular questions, the real problem lies in the question of truth."
Ratzinger refers to achievements of the
natural scienceThe natural sciences are branches of science that seek to elucidate the rules that govern the natural world by using empirical and scientific methods...
s as evidence that human reason has the power to know reality and arrive at truth. He also argues that "the modern self-limitation of reason" rooted in
Immanuel KantImmanuel Kant was a German philosopher from Königsberg , researching, lecturing and writing on philosophy and anthropology at the end of the 18th Century Enlightenment....
's philosophy, which views itself incapable of knowing religion and the
human scienceHuman science refers to the investigation of human life and activities via a phenomenological methodology that acknowledges the validity of both sensory and psychological experience...
s such as
ethicsEthics, also known as moral philosophy, is a branch of philosophy that addresses questions about morality—that is, concepts such as good and evil, right and wrong, virtue and vice, justice and crime, etc.Major branches of ethics include:...
, leads to dangerous pathologies of religion and pathologies of science. 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.
In his book
Truth and Tolerance, Ratzinger argued that truth and
loveLove is an emotion of strong affection and personal attachment. In philosophical context, love is a virtue representing all of human kindness, compassion, and affection. Love is central to many religions, as in the Christian phrase, "God is love" or Agape in the Canonical gospels...
are identical. And if well understood, according to him, this is "the surest guarantee of tolerance."
In medicine and psychiatry
There is controversy as to the truth value of a proposition made in
bad faithBad faith is double mindedness or double heartedness in duplicity, fraud, or deception. It may involve intentional deceit of others, or self deception....
self deception, such as when a hypochondriac has a complaint with no physical symptom.
See also
- Aletheia
- Asha
Asha is the Avestan language term for a concept of cardinal importance to Zoroastrian theology and doctrine. In the moral sphere, aša/arta represents what has been called "the decisive confessional concept of Zoroastrianism." ...
- Belief
Belief is the psychological state in which an individual holds a proposition or premise to be true.-Belief, knowledge and epistemology:The terms belief and knowledge are used differently in philosophy....
- Confirmation holism
Confirmation holism, also called epistemological holism is the claim that a single scientific theory cannot be tested in isolation; a test of one theory always depends on other theories and hypotheses....
- Contextualism
Contextualism describes a collection of views in philosophy which emphasize the context in which an action, utterance, or expression occurs, and argues that, in some important respect, the action, utterance, or expression can only be understood relative to that context...
- Contradiction
In classical logic, a contradiction consists of a logical incompatibility between two or more propositions. It occurs when the propositions, taken together, yield two conclusions which form the logical, usually opposite inversions of each other...
- Degrees of truth
- Disposition
A disposition is a habit, a preparation, a state of readiness, or a tendency to act in a specified way.The terms dispositional belief and occurrent belief refer, in the former case, to a belief that is held in the mind but not currently being considered, and in the latter case, to a belief that is...
- Eclecticism
Eclecticism is a conceptual approach that does not hold rigidly to a single paradigm or set of assumptions, but instead draws upon multiple theories, styles, or ideas to gain complementary insights into a subject, or applies different theories in particular cases.It can sometimes seem inelegant or...
- Golem: Earliest Stories
- Imagination
Imagination, also called the faculty of imagining, is the ability of forming mental images, sensations and concepts, in a moment when they are not perceived through sight, hearing or other senses...
- Independence
In mathematical logic, independence refers to the unprovability of a sentence from other sentences.A sentence σ is independent of a given first-order theory T if T neither proves nor refutes σ; that is, it is impossible to prove σ from T, and it is also impossible to prove from T that...
- Interpretation
An interpretation is an assignment of meaning to the symbols of a formal language. Many formal languages used in mathematics, logic, and theoretical computer science are defined in solely syntactic terms, and as such do not have any meaning until they are given some interpretation...
- Invariance
- Normative science
A normative science is a form of inquiry, typically involving a community of inquiry and its accumulated body of provisional knowledge, that seeks to discover good ways of achieving recognized aims, ends, goals, objectives, or purposes....
- Perspectivism
Perspectivism is the philosophical view developed by Friedrich Nietzsche that all ideations take place from particular perspectives. This means that there are many possible conceptual schemes, or perspectives in which judgment of truth or value can be made...
- Physical symbol system
A physical symbol system takes physical patterns , combining them into structures and manipulating them to produce new expressions....
- Public opinion
Public opinion is the aggregate of individual attitudes or beliefs held by the adult population. Public opinion can also be defined as the complex collection of opinions of many different people and the sum of all their views....
- Relativism
Relativism is the concept that points of view have no absolute truth or validity, having only relative, subjective value according to differences in perception and consideration....
- Religious truth
-The Four Noble Truths:The Four Noble Truths are the most fundamental Buddhist teachings and appear countless times throughout the most ancient Buddhist texts, the Pali Canon...
- Slingshot argument
In logic, a slingshot argument is one of a group of arguments claiming to show that all true sentences stand for the same thing.This type of argument was dubbed the "slingshot" by philosophers Jon Barwise and John Perry due to its disarming simplicity. Versions of the slingshot argument have been...
- Statistical independence
In probability theory, to say that two events are independent intuitively means that the occurrence of one event makes it neither more nor less probable that the other occurs...
- Tautology (logic)
In logic, a tautology is a formula which is true in every possible interpretation. Philosopher Ludwig Wittgenstein first applied the term to redundancies of propositional logic in 1921; it had been used earlier to refer to rhetorical tautologies, and continues to be used in that alternate sense...
- Tautology (rhetoric)
Tautology is an unnecessary or unessential repetition of meaning, using different and dissimilar words that effectively say the same thing...
- Truth prevails
"Truth prevails" is a motto, inscribed on the banner of the President of the Czech Republic, which is one of the national symbols according to the Czech Constitution. The phrase also appears along the base of the Jan Hus Memorial in Prague...
- Truthiness
Truthiness is a "truth" that a person claims to know intuitively "from the gut" or that it "feels right" without regard to evidence, logic, intellectual examination, or facts....
- Truthlikeness
- Two truths doctrine
The Buddhist doctrine of the two truths differentiates between two levels of truth in Buddhist discourse: a "relative" or commonsense truth , and an "ultimate" or absolute, spiritual truth...
- Unity of the proposition
In philosophy, the unity of the proposition is the problem of explaining how a sentence in the indicative mood expresses more than just what a list of proper names expresses.- History :...
- Verisimilitude
Verisimilitude is the quality of realism in something .-Competing ideas:The problem of verisimilitude is the problem of articulating what it takes for one false theory to be closer to the truth than another false theory...
- Veritas
In Roman mythology, Veritas, meaning truth, was the goddess of truth, a daughter of Saturn and the mother of Virtue. It was believed that she hid in the bottom of a holy well because she was so elusive. Her image is shown as a young virgin dressed in white...
- What is truth?
Major theorists
- Thomas Aquinas
Thomas Aquinas, O.P. , also Thomas of Aquin or Aquino, was an Italian Dominican priest of the Catholic Church, and an immensely influential philosopher and theologian in the tradition of scholasticism, known as Doctor Angelicus, Doctor Communis, or Doctor Universalis...
- Aristotle
Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...
- J.L. Austin
- Brand Blanshard
Percy Brand Blanshard was an American philosopher known primarily for his defense of reason. A powerful polemicist, by all accounts he comported himself with courtesy and grace in philosophical controversies and exemplified the "rational temper" he advocated.-Life:Brand Blanshard was born August...
- John Dewey
John Dewey was an American philosopher, psychologist and educational reformer whose ideas have been influential in education and social reform. Dewey was an important early developer of the philosophy of pragmatism and one of the founders of functional psychology...
- Hartry Field
Hartry H. Field is a philosopher, the Silver Professor of Philosophy at New York University. He previously taught at the University of Southern California and The Graduate Center of the City University of New York. He earned his Ph.D...
- Gottlob Frege
Friedrich Ludwig Gottlob Frege was a German mathematician, logician and philosopher. He is considered to be one of the founders of modern logic, and made major contributions to the foundations of mathematics. He is generally considered to be the father of analytic philosophy, for his writings on...
- Jürgen Habermas
Jürgen Habermas is a German sociologist and philosopher in the tradition of critical theory and pragmatism. He is perhaps best known for his theory on the concepts of 'communicative rationality' and the 'public sphere'...
- G. W. F. Hegel
- Martin Heidegger
Martin Heidegger was a German philosopher known for his existential and phenomenological explorations of the "question of Being."...
- Augustine of Hippo
Augustine of Hippo , also known as Augustine, St. Augustine, St. Austin, St. Augoustinos, Blessed Augustine, or St. Augustine the Blessed, was Bishop of Hippo Regius . He was a Latin-speaking philosopher and theologian who lived in the Roman Africa Province...
- Paul Horwich
Paul Horwich is a British analytic philosopher at New York University, whose work includes writings on causality, the philosophy of language and Wittgenstein's later philosophy. Horwich earned his PhD from Cornell University; his thesis advisor was Richard Boyd...
- William James
William James was a pioneering American psychologist and philosopher who was trained as a physician. He wrote influential books on the young science of psychology, educational psychology, psychology of religious experience and mysticism, and on the philosophy of pragmatism...
- Harold Joachim
Harold Henry Joachim was a British idealist philosopher. A disciple of Francis Herbert Bradley, whose posthumous papers he edited, Joachim is now identified with the later days of the British Idealist movement. He is generally credited with the definitive formulation of the coherence theory of...
- Saul Kripke
Saul Aaron Kripke is an American philosopher and logician. He is a professor emeritus at Princeton and teaches as a Distinguished Professor of Philosophy at the CUNY Graduate Center...
- Friedrich Nietzsche
Friedrich Wilhelm Nietzsche was a 19th-century German philosopher, poet, composer and classical philologist...
- Charles Sanders Peirce
- Plato
Plato , was a Classical Greek philosopher, mathematician, student of Socrates, writer of philosophical dialogues, and founder of the Academy in Athens, the first institution of higher learning in the Western world. Along with his mentor, Socrates, and his student, Aristotle, Plato helped to lay the...
- Karl Popper
Sir Karl Raimund Popper, CH FRS FBA was an Austro-British philosopher and a professor at the London School of Economics...
- W.V. Quine
- Frank P. Ramsey
Frank Plumpton Ramsey was a British mathematician who, in addition to mathematics, made significant and precocious contributions in philosophy and economics before his death at the age of 26...
- Bertrand Russell
Bertrand Arthur William Russell, 3rd Earl Russell, OM, FRS was a British philosopher, logician, mathematician, historian, and social critic. At various points in his life he considered himself a liberal, a socialist, and a pacifist, but he also admitted that he had never been any of these things...
- Arthur Schopenhauer
Arthur Schopenhauer was a German philosopher known for his pessimism and philosophical clarity. At age 25, he published his doctoral dissertation, On the Fourfold Root of the Principle of Sufficient Reason, which examined the four separate manifestations of reason in the phenomenal...
- Socrates
Socrates was a classical Greek Athenian philosopher. Credited as one of the founders of Western philosophy, he is an enigmatic figure known chiefly through the accounts of later classical writers, especially the writings of his students Plato and Xenophon, and the plays of his contemporary ...
- P.F. Strawson
- Alfred Tarski
Alfred Tarski was a Polish logician and mathematician. Educated at the University of Warsaw and a member of the Lwow-Warsaw School of Logic and the Warsaw School of Mathematics and philosophy, he emigrated to the USA in 1939, and taught and carried out research in mathematics at the University of...
- Mahatma Gandhi
Mohandas Karamchand Gandhi , pronounced . 2 October 1869 – 30 January 1948) was the pre-eminent political and ideological leader of India during the Indian independence movement...
- Ludwig Wittgenstein
Ludwig Josef Johann Wittgenstein was an Austrian philosopher who worked primarily in logic, the philosophy of mathematics, the philosophy of mind, and the philosophy of language. He was professor in philosophy at the University of Cambridge from 1939 until 1947...
External links