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Five different forms of truth skepticism are examined and defused: the view that truth is indefinable, that it is unattainable and unknowable, that it is inextricably metaphysical and hence not scientifically respectable, that there is no such thing as truth, and that truth is inherently paradoxical, and so must either be abandoned or revised. An intriguing formulation of the last of these views is owing to Alfred Tarski, who argued that the Liar paradox shows natural languages to be inconsistent because they contain defective, and ultimately incoherent truth predicates. Here, it is argued in response that on a plausible interpretation of his puzzling notion of an inconsistent language, Tarski's argument is, though logically valid, almost certainly unsound, since one of its premises is highly problematic. Similar results are achieved for other forms of truth skepticism.

In proving that the language of arithmetic does not contain its own truth predicate, Tarski demonstrated that the claim that a language both satisfies certain minimal conditions and contains its own truth predicate leads to a contradiction – a result that can seem puzzling in light of the fact that it seems obvious that English does satisfy the relevant conditions, while containing its own truth predicate (though of course this cannot be). Chapter 5 explores the well‐known response to this problem (a version of the Liar paradox), which maintains that English is really an infinite hierarchy of languages defined by a hierarchy of Tarski‐style truth predicates. The construction of the hierarchy is explained, and the ways in which it is used to block different versions of the paradox are illustrated. The discussion then turns to problems with the approach, the most serious being the irresistible urge to violate the hierarchy's restrictions on intelligibility in the very process of setting it up – something we tend to forget because we imagine ourselves taking a position outside the hierarchy from which it can be described. Once we realize that the hierarchy is supposed to apply to the language we are using to describe it, the paradox returns with a vengeance, threatening to destroy the very construction that was introduced to avoid it.

Presents a philosophical model of partially defined predicates, illustrates how a language could come to contain them, and provides a natural way of understanding the truth predicate in which it conforms to this model. On this view, there are sentences, including Liar sentences like this sentence is not true and “Truth Tellers” like This sentence is true, about which the rules determining whether or not a sentence is true provide no result (either to the effect that it is true, or to the effect that it is not true) – thereby blocking the usual derivation of the paradox. However, despite these promising results, it is shown that a general solution to the Liar paradox is not forthcoming, since the very activity of solving the paradox in a particular limited case provides material for recreating it in a new and strengthened form. In the second half of the chapter, it is argued that this philosophical model provides the best way of understanding Saul Kripke's formal theory of truth (despite certain uncharacteristically misleading remarks of his to the contrary). In addition to laying out the philosophical basis for Kripke's theory of truth, explanations are given of his basic technical apparatus and formal results – including fixed points, minimal fixed points, monotonicity, intrinsic fixed points, ungrounded sentences, and paradoxical sentences.