Truth

The English word true is from Old English (West Saxon) (ge)tríewe, tréowe, cognate to Old Saxon (gi)trûui, Old High German (ga)triuwu (Modern German treu "faithful"), Old Norse tryggr, Gothic triggws,[5] all from a Proto-Germanic *trewwj- "having good faith", perhaps ultimately from PIE *dru- "tree", on the notion of "steadfast as an oak" (e.g., Sanskrit dā́ru "(piece of) wood").

Thus, "truth" in its ordinary usage involves both the quality of "faithfulness, fidelity, loyalty, sincerity, veracity",[8] and that of "agreement with fact or reality", in Anglo-Saxon expressed by sōþ (Modern English sooth).

Romance languages use terms following the Latin veritas, while the Greek aletheia, Russian pravda, South Slavic istina and Sanskrit sat (related to English sooth and North Germanic sanna) have separate etymological origins.

[18] Correspondence theory centres around the assumption that truth is a matter of accurately copying what is known as "objective reality" and then representing it in thoughts, words, and other symbols.

Three influential forms of the pragmatic theory of truth 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 all hold that truth is verified and confirmed by the results of putting one's concepts into practice.

"[27] 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 truth.

[35] Modern developments in the field of philosophy have resulted in the rise of a new thesis: that the term truth does not denote a real property of sentences or propositions.

Yet another version of deflationism is the prosentential theory of truth, first developed by Dorothy Grover, Joseph Camp, and Nuel Belnap as an elaboration of Ramsey's claims.

Radical forms of skepticism deny that knowledge or rational belief is possible and urge us to suspend judgment regarding ascription of truth on many or all controversial matters.

[54] 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.

In propositional logic, these symbols can be manipulated according to a set of axioms and rules of inference, often given in the form of truth tables.

[55] The works of Kurt Gödel, Alan Turing, and others shook this assumption, with the development of statements that are true but cannot be proven within the system.

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.

These intuitions include:[69] Like many folk theories, the folk theory of truth is useful in everyday life but, upon deep analysis, turns out to be technically self-contradictory; in particular, any formal system that fully obeys "capture and release" semantics for truth (also known as the T-schema), and that also respects classical logic, is provably inconsistent and succumbs to the liar paradox or to a similar contradiction.

[77]Reevaluating Avicenna, and also Augustine and Aristotle, Thomas Aquinas stated in his Disputed Questions on Truth: A natural thing, being placed between two intellects, is called true insofar as it conforms to either.

The idea of the oath, which was so much part and parcel of for instance Romance literature,[80] changes from a subjective concept to a more objective one (in Derek Pearsall's summary).

[71] Kant writes in the Critique of Pure Reason: "The nominal definition of truth, namely that it is the agreement of cognition with its object, is here granted and presupposed".

According to Kant, the ancient skeptics were critical of the logicians for holding that, by means of a merely nominal definition of truth, they can establish which judgements are true.

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.

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.

A mobile army of metaphors, metonyms, and anthropomorphisms – in short, a sum of human relations which have been enhanced, transposed, and embellished poetically and rhetorically ..."Nietzsche argues that truth is always filtered through individual perspectives and shaped by various interests and biases.

"[95] He suggests that truth is subject to constant reinterpretation and change, influenced by shifting cultural and historical contexts as he writes in "Thus Spoke Zarathustra" that "I say unto you: one must still have chaos in oneself to be able to give birth to a dancing star.

[102] This first existentialist theory, more fully fleshed out in Sartre's essay Truth and Existence (1948), which already demonstrates a more radical departure from Heidegger in its emphasis on the primacy of the idea, already formulated in Being and Nothingness, of existence as preceding essence in its role in the formulation of truth, has nevertheless been critically examined as idealist rather than materialist in its departure from more traditional idealist epistemologies such as those of Ancient Greek philosophy in Plato and Aristotle, and staying as does Heidegger with Kant.

[103] Later, in the Search for a Method (1957), in which Sartre used a unification of existentialism and Marxism that he would later formulate in the Critique of Dialectical Reason (1960), Sartre, with his growing emphasis on the Hegelian totalisation of historicity, posited a conception of truth still defined by its process of relation to a container giving it material meaning, but with specific reference to a role in this broader totalisation, for "subjectivity is neither everything nor nothing; it represents a moment in the objective process (that in which externality is internalised), and this moment is perpetually eliminated only to be perpetually reborn": "For us, truth is something which becomes, it has and will have become.

... 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 the desired result".