The question of what is a proper basis for deciding how words, symbols, ideas and beliefs may properly be considered to truthfully denote meaning, whether by a single person or by an entire society, has been considered by five major types of theory of meaning and truth. Each type is discussed below, together with its principal exponents.
Substantive theories of meaning Correspondence theory Correspondence theories emphasise that true beliefs and true statements of meaning correspond to the actual state of affairs and that associated meanings must be in agreement with these beliefs and statements. This type of theory stresses a relationship between thoughts or statements on one hand, and things or objects on the other. It is a traditional model tracing its origins to
ancient Greek philosophers such as
Socrates,
Plato, and
Aristotle. This class of theories holds that the truth or the falsity of a representation is determined in principle entirely by how it relates to "things", by whether it accurately describes those "things". An example of correspondence theory is the statement by the thirteenth-century philosopher/theologian
Thomas Aquinas:
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 Israeli. Aquinas also restated the theory as: "A judgment is said to be true when it conforms to the external reality". Correspondence theory centres heavily around the assumption that truth and meaning are a matter of accurately copying what is known as "
objective reality" and then representing it in thoughts, words and other symbols. Many modern theorists have stated that this ideal cannot be achieved without analysing additional factors. For example, language plays a role in that all languages have words to represent concepts that are virtually undefined in other languages. The
German word
Zeitgeist 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 predicate. Among the philosophers who grappled with this problem is
Alfred Tarski, whose
semantic theory is summarized further below in this article.
Coherence theory For coherence theories in general, the assessment of meaning and 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 describe the essential and intrinsic properties of
formal systems in logic and mathematics. However, formal reasoners are content to contemplate
axiomatically independent and sometimes mutually contradictory systems side by sidefor example, the various
alternative geometries. On the whole, coherence theories have been rejected for lacking justification in their application to other areas of truthespecially with respect to assertions about the
natural world,
empirical data in general, assertions about practical matters of psychology and societyparticularly when used without support from the other major theories of truth. Coherence theories distinguish the thought of
rationalist philosophers, particularly of
Spinoza,
Leibniz, and
G.W.F. Hegel, along with the British philosopher
F.H. Bradley. Other alternatives may be found among several proponents of
logical positivism, notably
Otto Neurath and
Carl Hempel.
Constructivist theory Social constructivism holds that meaning and truth are constructed by social processes, are historically and culturally specific, and are in part shaped through power struggles within a community. Constructivism views all of our knowledge as "constructed", because it does not reflect any external "transcendent" realities (as a pure correspondence theory might hold). Rather, perceptions of truth are viewed as contingent on convention, human perception, and social experience. It is believed by constructivists that representations of physical and biological reality, including
race,
sexuality, and
gender, are socially constructed.
Giambattista Vico was among the first to claim that history and culture, along with their meaning, are human products. 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 is "an epiphenomenal expression of the relation of material forces in a given economic arrangement".
Consensus theory Consensus theory holds that meaning and truth are whatever is agreed uponor, in some versions, might come to be agreed uponby some specified group. Such a group might include all human beings, or a
subset thereof consisting of more than one person. Among the current advocates of consensus theory as a useful accounting of the concept of "truth" is the philosopher
Jürgen Habermas. Habermas maintains that truth is what would be agreed upon in an
ideal speech situation. Among the recent strong critics of consensus theory has been the philosopher
Nicholas Rescher.
Pragmatic theory The three most influential forms of the
pragmatic theory of truth and meaning were introduced around the turn of the 20th century by
Charles Sanders Peirce,
William James, and
John Dewey. Although there are wide differences in viewpoint among these and other proponents of pragmatic theory, they hold in common that meaning and truth are 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 stresses Peirce's view that ideas of approximation, incompleteness, and partiality, what he describes elsewhere as
fallibilism and "reference to the future", are essential to a proper conception of meaning and truth. Although Peirce uses words like
concordance and
correspondence to describe one aspect of the pragmatic
sign relation, he is also quite explicit in saying that definitions of truth based on mere correspondence are no more than
nominal definitions, which he accords a lower status than
real definitions.
William James's version of pragmatic theory, while complex, is often summarized by his statement that "the 'true' is only the expedient in our way of thinking, just as the 'right' is only the expedient in our way of behaving". By this, James meant that truth is a
quality, the value of which is confirmed by its effectiveness when applying concepts to practice (thus, "pragmatic").
John Dewey, less broadly than James but more broadly than Peirce, held that
inquiry, whether scientific, technical, sociological, philosophical or cultural, is self-corrective over time
if openly submitted for testing by a community of inquirers in order to clarify, justify, refine and/or refute proposed meanings and truths. A later variation of the pragmatic theory was
William Ernest Hocking's "negative pragmatism": what works may or may not be true, but what fails cannot be true, because the truth and its meaning always works. James's and Dewey's ideas also ascribe meaning and truth to repeated testing, which is "self-corrective" over time. Pragmatism and negative pragmatism are also closely aligned with the
coherence theory of truth 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 acknowledge and account for its diversity. As physicist
Richard Feynman said: "if it disagrees with experiment, it is wrong".
Associated theories and commentaries Some have asserted that meaning is nothing substantially more or less than the
truth conditions they involve. For such theories, an emphasis is placed upon
reference to actual things in the world to account for meaning, with the caveat that reference more or less explains the greater part (or all) of meaning itself.
Logic and language The
logical positivists argued that the meaning of a statement arose from
how it is verified.
Gottlob Frege In his paper "
Über Sinn und Bedeutung" (now usually translated as "On Sense and Reference"),
Gottlob Frege argued that proper names present at least two problems in explaining meaning. • Suppose the meaning of a name is the thing it refers to.
Sam, then, means a person in the world who is named Sam. But if the object referred to by the name did not exist—i.e.,
Pegasus—then, according to that theory, it would be meaningless. • Suppose two different names refer to the same object.
Hesperus and
Phosphorus were the names given to what were considered distinct celestial bodies. It was later shown that they were the same thing (the planet Venus). If the words meant the same thing, then substituting one for the other in a sentence would not result in a sentence that differs in meaning from the original. But in that case, "Hesperus is Phosphorus" would mean the same thing as "Hesperus is Hesperus". This is clearly absurd, since we learn something new and unobvious by the former statement, but not by the latter. Frege can be interpreted as arguing that it was therefore a mistake to think that the meaning of a name is the thing it refers to. Instead, the meaning must be something else—the "sense" of the word. Two names for the same person, then, can have different senses (or meanings): one referent might be picked out by more than one sense. This sort of theory is called a
mediated reference theory. Frege argued that, ultimately, the same bifurcation of meaning must apply to most or all linguistic categories, such as to quantificational expressions like "All boats float".
Bertrand Russell Logical analysis was further advanced by
Bertrand Russell and
Alfred North Whitehead in their groundbreaking
Principia Mathematica, which attempted to produce a formal language with which the truth of all mathematical statements could be demonstrated from first principles. Russell differed from Frege greatly on many points, however. He rejected Frege's sense-reference distinction. He also disagreed that language was of fundamental significance to philosophy, and saw the project of developing formal logic as a way of eliminating all of the confusions caused by ordinary language, and hence at creating a perfectly transparent medium in which to conduct traditional philosophical argument. He hoped, ultimately, to extend the proofs of the
Principia to all possible true statements, a scheme he called
logical atomism. For a while it appeared that his pupil
Wittgenstein had succeeded in this plan with his
Tractatus Logico-Philosophicus. Russell's work, and that of his colleague
G. E. Moore, developed in response to what they perceived as the nonsense dominating British philosophy departments at the turn of the 20th century, which was a kind of
British Idealism most of which was derived (albeit very distantly) from the work of
Hegel. In response Moore developed an approach ("Common Sense Philosophy") which sought to examine philosophical difficulties by a close analysis of the language used in order to determine its meaning. In this way Moore sought to expunge philosophical absurdities such as "time is unreal". Moore's work would have significant, if oblique, influence (largely mediated by
Wittgenstein) on
Ordinary language philosophy.
Other truth theories of meaning The
Vienna Circle, a famous group of
logical positivists from the early 20th century (closely allied with Russell and Frege), adopted the
verificationist theory of meaning, a type of
truth theory of meaning. The verificationist theory of meaning (in at least one of its forms) states that to say that an expression is meaningful is to say that there are some conditions of experience that could exist to show that the expression is true. As noted, Frege and Russell were two proponents of this way of thinking. A
semantic theory of truth was produced by
Alfred Tarski for
formal semantics. According to Tarski's account, meaning consists of a recursive set of rules that end up yielding an infinite set of sentences, "'p' is true if and only if p", covering the whole language. His innovation produced the notion of
propositional functions discussed on the section on
universals (which he called "sentential functions"), and a
model-theoretic approach to semantics (as opposed to a
proof-theoretic one). Finally, some links were forged to the
correspondence theory of truth (Tarski, 1944). Perhaps the most influential current approach in the contemporary theory of meaning is that sketched by
Donald Davidson in his introduction to the collection of essays
Truth and Meaning in 1967. There he argued for the following two theses: • Any learnable language must be statable in a finite form, even if it is capable of a theoretically infinite number of expressions—as we may assume that natural human languages are, at least in principle. If it could not be stated in a finite way then it could not be learned through a finite, empirical method such as the way humans learn their languages. It follows that it must be possible to give a theoretical semantics for any natural language which could give the meanings of an infinite number of sentences on the basis of a finite system of axioms. • Giving the meaning of a sentence, he further argued, was equivalent to stating its
truth conditions. He proposed that it must be possible to account for language as a set of distinct grammatical features together with a lexicon, and for each of them explain its workings in such a way as to generate trivial (obviously correct) statements of the truth conditions of all the (infinitely many) sentences built up from these. The result is a theory of meaning that rather resembles, by no accident, Tarski's account. Davidson's account, though brief, constitutes the first systematic presentation of
truth-conditional semantics. He proposed simply translating natural languages into
first-order predicate calculus in order to reduce meaning to a function of truth.
Saul Kripke Saul Kripke examined the relation between sense and reference in dealing with possible and actual situations. He showed that one consequence of his interpretation of certain systems of
modal logic was that the reference of a proper name is
necessarily linked to its
referent, but that the sense is not. So for instance "Hesperus" necessarily refers to Hesperus, even in those imaginary cases and worlds in which perhaps Hesperus is not the evening star. That is, Hesperus is necessarily Hesperus, but only contingently the morning star. This results in the curious situation that part of the meaning of a name — that it refers to some particular thing — is a necessary fact about that name, but another part — that it is used in some particular way or situation — is not. Kripke also drew the distinction between speaker's meaning and semantic meaning, elaborating on the work of ordinary language philosophers
Paul Grice and
Keith Donnellan. The speaker's meaning is what the speaker intends to refer to by saying something; the semantic meaning is what the words uttered by the speaker mean according to the language. In some cases, people do not say what they mean; in other cases, they say something that is in error. In both these cases, the speaker's meaning and the semantic meaning seem to be different. Sometimes words do not actually express what the speaker wants them to express; so words will mean one thing, and what people intend to convey by them might mean another. The meaning of the expression, in such cases, is ambiguous.
Critiques of truth theories of meaning W. V. O. Quine attacked both verificationism and the very notion of meaning in his famous essay, "
Two Dogmas of Empiricism". In it, he suggested that meaning was nothing more than a vague and dispensable notion. Instead, he asserted, what was more interesting to study was the synonymy between signs. He also pointed out that verificationism was tied to the distinction between
analytic and
synthetic statements, and asserted that such a divide was defended ambiguously. He also suggested that the unit of analysis for any potential investigation into the world (and, perhaps, meaning) would be the entire body of statements taken as a collective, not just individual statements on their own. Other criticisms can be raised on the basis of the limitations that truth-conditional theorists themselves admit to. Tarski, for instance, recognized that truth-conditional theories of meaning only make sense of statements, but fail to explain the meanings of the lexical parts that make up statements. Rather, the meaning of the parts of statements is presupposed by an understanding of the truth-conditions of a whole statement, and explained in terms of what he called "satisfaction conditions". Still another objection (noted by Frege and others) was that some kinds of statements do not seem to have any truth-conditions at all. For instance, "Hello!" has no truth-conditions, because it does not even attempt to tell the listener anything about the
state of affairs in the world. In other words, different propositions have different
grammatical moods.
Deflationist accounts of truth, sometimes called 'irrealist' accounts, are the staunchest source of criticism of truth-conditional theories of meaning. According to them, "truth" is a word with no serious meaning or function in discourse. For instance, for the deflationist, the sentences "It's true that Tiny Tim is trouble" and "Tiny Tim is trouble" are equivalent. In consequence, for the deflationist, any appeal to truth as an account of meaning has little explanatory power. The sort of truth theories presented here can also be attacked for their
formalism both in practice and principle. The principle of formalism is challenged by the
informalists, who suggest that language is largely a construction of the speaker, and so, not compatible with formalization. The practice of formalism is challenged by those who observe that formal languages (such as present-day quantificational logic) fail to capture the expressive power of natural languages (as is arguably demonstrated in the awkward character of the quantificational explanation of definite description statements, as laid out by Bertrand Russell). Finally, over the past century, forms of logic have been developed that are not dependent exclusively on the notions of truth and falsity. Some of these types of logic have been called
modal logics. They explain how certain logical connectives such as "if-then" work in terms of necessity and
possibility. Indeed, modal logic was the basis of one of the most popular and rigorous formulations in modern semantics called the
Montague grammar. The successes of such systems naturally give rise to the argument that these systems have captured the natural meaning of connectives like if-then far better than an ordinary, truth-functional logic ever could. ==Usage and meaning==