Edited by Kevin Scharp (University of St. Andrews)
|Summary||A liar paradox is generated by a sentence or proposition (or any truth bearer more generally) that says that it is false. If we use the name 'S' for the sentence ‘S is false’, then that very sentence says of itself that it is false. We can reason intuitively that if it is true, then what it says is true, namely that it is false. So it is true that it is false, or, more directly, it is false. On the other hand, if it is false, then what it says is false, namely that it is false. So it is false that it is false, or, more directly, it is true. Thus, we derive that it is false from the assumption that it is true, and we derive that it is true from the assumption that it is false. It takes just a couple of steps from here to the claim that S is both true and false. The above reasoning relies on the following two principles regarding truth (for some class of sentences p of which S is a member): (i) if p is true, then p, and (ii) if p, then p is true. It also relies on principles of classical (and intuitionistic) logic. Approaches to the liar paradox usually reject one of the principles of truth, one of the logical principles, or find some defect in S and any other sentence like it. The liar paradox is closely related to several other paradoxes associated with truth, including Curry's paradox and Yablo's paradox.|
|Key works||The classic work on the liar paradox in analytic philosophy is Tarski 1936. Kripke 1975 solidified the importance of logical rigor in investigations of the liar paradox. Early contextual approaches include Parsons 1974 and Burge 1979. Priest 1979 and Chihara 1979 initiated the inconsistency approach. Gupta 1982 and Herzberger 1982 were the first to offer revision theories of truth.|
|Introductions||Introductory works include the Stanford Encyclopedia of Philosophy entry: Beall & Glanzberg 2010|
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