Theories of truth aim to identify what all truths have in common. Their goal is not to list true statements but to clarify the
concept of truth, discern its
essential features, and explain truth-related phenomena. There are disagreements about whether such features exist and whether a given feature is an essential component or an external criterion only indicating the presence of truth.
Correspondence File:Correspondence theory of truth.svg|thumb|alt=A red apple, and the statement "[This] apple is red."|According to the correspondence theory, a statement is true if it corresponds to facts. The correspondence theory asserts that a belief or statement is true if it corresponds to facts. This view emphasizes the relation between thought or language and reality, arguing that truth matches how things are. It is one of the oldest and most influential theories of truth. One version asserts a one-to-one correlation between truths and facts, while another understands correspondence more broadly as a structural similarity that does not require a perfect one-to-one mirroring.
Truthmaker theory is closely related to correspondence theory and is often treated as a modern version of it. Truthmaker theory stresses that truth depends on reality and analyzes the relation between truths and their truthmakers. Its most comprehensive form is truthmaker maximalism, which asserts that every truth has a truthmaker. Atomic truthmaker theory, by contrast, limits this view to simple statements and analyzes the truth of complex statements in terms of simpler ones. A key motivation for the correspondence theory is its intuitive appeal and its ability to ground truth in objective reality. A key challenge is to clarify how exactly truths relate to facts. Critics hold that the correspondence theory is uninformative or circular because it fails to explain what
correspondence means. They argue that it assumes an implicit understanding of the relation without offering an independent account. Another objection asserts that the correspondence theory is too narrow because it is unable to explain truth in fields like mathematics, logic, and morality, where it is more difficult to identify independent facts corresponding to statements.
Coherence The coherence theory understands truth as a relation between beliefs rather than between a belief and a fact. It asserts that a belief is true if it is part of a coherent web of beliefs. Coherence theorists typically stress that beliefs do not occur in isolation but are part of a broader perspective on reality since they depend on conceptual frameworks and background assumptions not explicitly represented in the content of each belief. For example, the belief that
photons lack mass rests on a network of ideas from
particle physics that ground its meaning and ramifications. Accordingly, coherence theory is associated with a form of
holism that privileges comprehensive perspectives over individual beliefs. In the strongest form, coherentism requires that all beliefs cohere. Less demanding versions assert that only the majority of beliefs need to cohere or that coherence is required within specific domains, such as scientific or moral beliefs, but not across domains. One criticism acknowledges that coherence is relevant for testing or verifying what is true but contends that coherence theory confuses criteria of verification with truth itself. Another objection argues that there can be competing coherent sets of beliefs where one set contradicts the other, meaning that coherence alone cannot determine which set is correct. For example, a fictional story does not become true just because it is coherent. A central difficulty for utility-based theories is that practical consequences and usefulness depend on situations and desires. This can lead to
subjectivism or
relativism since what is useful in one case may not be in another. Another challenge is that although practical consequences often align with truth, this is not always the case: a false belief may have good consequences in certain situations. A different version of pragmatism defines truth from the perspective of scientific research. It holds that truth is the ideal limit of inquiry or what researchers would believe after unlimited investigation. Other pragmatist approaches define truth as beliefs that have withstood thorough examination or as statements that fulfill discourse norms and can be asserted with warrant.
Semantic formulated the semantic theory of truth. The semantic theory characterizes truth in terms of
truth conditions. It distinguishes between an object language, which contains true sentences that are being analyzed, and a
meta-language to express their truth conditions using so-called T-sentences. T-sentences have the form: '"S" is true in L if and only if p' where L is the object language, S is a sentence of the object language, and p is a sentence of the meta-language describing truth conditions. For example, '"La nieve es blanca." is true in Spanish if and only if snow is white' is a T-sentence with Spanish as the object language and English as the meta-language. The semantic theory was originally formulated by
Alfred Tarski, who limited it to the analysis of
formal languages. Subsequent philosophers, such as
Donald Davidson, have also applied it to
natural languages. The semantic theory is often combined with the idea that truth conditions can be analyzed by
studying the components of sentences, such as names and predicates, which are then interpreted to refer to certain entities or situations described in the truth conditions. A key motivation for the semantic theory is its ability to characterize truth in a precise manner without introducing metaphysical assumptions concerning the existence and nature of facts, correspondence, or coherence. By talking about truth in the object language through a metalanguage, it also avoids paradoxes that arise if a language contains its own truth-predicate, such as the liar paradox. However, it is controversial to what extent the semantic theory offers substantial insights into the nature of truth rather than only providing a formal device for analyzing truth.
Deflationary 's rhetorical question to
Jesus, asking "
What is truth?" Deflationary theories argue that truth has no significant or interesting intrinsic nature. They hold that attempts by substantive or robust theories, such as correspondence theory and coherence theory, misconstrue truth by assuming a deep metaphysical structure, engaging in pseudoproblems where trivial answers would suffice. Deflationists typically analyze how truth-related expressions are used in language, holding that understanding their linguistic roles exhausts the concept of truth. Different deflationary theories propose distinct accounts of the linguistic function of truth-related terms. The
redundancy theory asserts that the predicate "is true" is superfluous and does not contribute to meaning. According to this view, the sentences 'Snow is white.' and '"Snow is white" is true.' have the same meaning. Disquotationalism holds that the predicate "is true" acts as a linguistic device to remove quotation marks and make generalizations. The performative theory treats truth as a performative expression that speakers can use to endorse statements, like when saying "That's true."
Prosententialism treats truth not as a regular predicate but as an operator. This operator can be applied to expressions that refer to other statements, as in "What Smith said is true." Minimalism understands truth as a logical property whose role is expressed in T-sentences. Various criticisms of deflationism target specific versions of it, such as criticisms of the redundancy theory or minimalism. However, there are also broader objections that seek to undermine deflationism in general. One argument holds that deflationism fails to explain key aspects of truth, like that truth serves as the aim of beliefs or that theoretical truth can lead to practical success.
Others Pluralists hold that there is no unified concept of truth that covers all cases. Instead, they argue that truth is a heterogeneous notion and that different theories apply to different domains. For example, a pluralist may accept the correspondence theory for empirical truths but adopt the coherence theory for mathematical truths. Absolutism asserts that truth is the same for everyone, meaning that what is true does not depend on individual standpoints, opinions, or contexts. It contrasts with
relativism, which maintains that the same statement can be true in one perspective or
context and false in another. Local relativism limits this dependency to particular domains, such as moral truth. Global relativism, by contrast, extends this view to all truths. Critics argue that global relativism is self-defeating theory that undermines its own authority: applied to itself, it holds that it is only true in some perspectives that all truths are relative.
Nihilism or skepticism about truth presents a more radical view that rejects the existence of truth. One common categorization divides theories of truth into
realism and
anti-realism. Realists see truth as an objective feature that is determined by what the world is like and exists independently of thoughts and descriptions. Anti-realists argue that truth depends in part or entirely on the epistemic situation or how beliefs relate to justification, verification, inquiry, or one another. Realism is typically associated with absolutism, while anti-realism is more closely linked to relativism.
Verificationism argues that a statement is true if it is verifiable. It maintains that the procedures for confirming or disconfirming claims are not external tests of truth but constitutive norms. Verificationists typically assert that there are different verification procedures for different claims, for example, that scientific claims about empirical phenomena require observation and experimentation, whereas mathematical claims are established through deductive proof. What is verifiable or falsifiable depends on the situation and the abilities of investigators, meaning that verificationist truth is not purely objective. Additionally, some statements may be neither verifiable nor falsifiable, raising the question of whether verificationism requires a third truth value or truth-value gaps. Verificationism is sometimes grouped with coherentism as an
epistemic theory. Epistemic theories define truth in terms of epistemic concepts, including coherence, verifiability,
justification, and
rationality. The identity theory holds that something is true if it is identical to reality. This view rejects the distinction between truthbearers and truthmakers, arguing that truths are facts rather than representations. Axiomatic theories are deductive theories based on a small number of
fundamental principles. Instead of providing explicit definitions, they treat truth as a primitive or undefined concept and formulate general rules of how it behaves. According to the
consensus theory, proposed by
Jürgen Habermas, truth is what people would agree upon under ideal circumstances. The term
folk theory of truth refers to widely held beliefs of ordinary people about truth, like the idea that a proposition is true if its negation is false. Theories of truth are challenged by various
paradoxes in which basic intuitions or principles yield
contradictory conclusions. The
liar paradox involves a statement with an inconsistent truth assignment, like the claims "I am lying" or "This statement is false": if the statement is true, it follows that it is false, and if it is false, it follows that it is true. Other paradoxes include the
Curry paradox, the
Russell-Myhill paradox, and Grelling's paradox. Some paradoxes arise if a language contains its own
truth predicate. Tarski sought to avoid this problem by analyzing formal languages that do not have truth predicates.
Saul Kripke proposed a different approach that limits how truth predicates can be used within a language without excluding them. == Types ==