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According 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 white". Redundancy theorists infer from this premise that truth is a redundant concept, in other words, that "truth" is a mere word that is conventional to use in certain contexts of discourse but not a word that points to anything in reality. The theory is commonly attributed to Frank P. Ramsey, who argued that the use of words like ''fact'' and ''truth'' was nothing but a roundabout way of asserting a proposition, and that treating these words as separate problems in isolation from judgment was merely a "linguistic muddle", though there remains some debate as to the correct interpretation of his position (Le Morvan 2004). Redundancy theorists begin by inquiring into the function of the predicate "__is true" in sentences like " 'Snow is white' is true". They reason that asserting the longer sentence is equivalent to asserting the shorter sentence "Snow is white". From this they infer that nothing is added to the ''assertion'' of the sentence "Snow is white" by quoting it, appending the predicate "__is true", and then asserting the result. Most predicates attribute properties to their subjects, but the redundancy theory denies that the predicate ''is true'' does so. Instead, it treats the predicate ''is true'' as empty, adding nothing to an assertion except to convert its use to its mention. That is, the predicate "___is true" merely asserts the proposition contained in the sentential clause to which it is applied but does not ascribe any additional property to that proposition or sentence, and in Ramsey's British lexicon, "is true" is redundant. ==Ramsey's approach== Ramsey's paper "Facts and Propositions" (1927) is frequently cited as the precipitating contribution in the current of thought that came to be called the redundancy theory of truth. But before we proceed further with the analysis of judgment, it is necessary to say something about truth and falsehood, in order to show that there is really no separate problem of truth but merely a linguistic muddle. (p. 38). Starting in a context of discussion that is concerned with analyzing judgment, in effect, the matter of asserting or denying propositions, Ramsey turns to the question of truth and falsehood, and suggests that these words add nothing of substance to the analysis of judgment already in progress.
In the course of his argument, Ramsey observes that there are many different ways of asserting what is really the same proposition, at least, so far as the abstract logical meanings of sentences are concerned. In his first examples, he uses the verbal forms (1) 'It is true that ___' and (2) 'It is false that ___', for the sake of concreteness filling in the blanks with the sentential clause 'Caesar was murdered'. He says that assertions mediated by these forms are not distinct in meaning from the corresponding direct assertions.
In the same context and by the same token, Ramsey cites the verbal forms (3) 'It is a fact that ___' and (4) '___ is contrary to fact' as further examples of dispensable, otiose, redundant, or purely stylistic verbiage.
The strategy of Ramsey's argument is to demonstrate that certain figures of speech — those in which truth and falsehood seem to figure as real properties of propositions, or as logical values that constitute real objects, however abstract, of discussion and thought — can always be eliminated in favor of paraphrases that do not reify ''truth'' and ''falsehood'' as nouns, nor even use ''true'' and ''false'' as adjectives. The plausibility of this tactic going through is fairly evident in the case of verbal forms that introduce direct or indirect quotations. But the feasibility of the conversion is less clear in the case of propositions whose contents are not given in full, but only by indirect or partial description.
The type of ''propositional function'' that Ramsey is referring to here is a function that takes a proposition as input and gives a proposition as output. In this case, the propositional function of interest is one that takes any proposition ''p'' and returns a proposition of the form p'' is true'.
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