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Institute for Logic, Language and Computation

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3 June 2008, Truth values, neither-true-nor-false, and supervaluations, Nuel Belnap

Speaker: Nuel Belnap
Date: Tuesday 3 June 2008
Time: 12:00 - 13:00
Location: Room 032, Ruppertgebouw, Leuvenlaan, entrance 'educatorium', Utrecht
(Bus 11 or 12 from Utrecht Central Station).

The first part of this essay defends reliance on truth values against those who, on nominalistic grounds, would uniformly substitute a truth predicate. I rehearse some practical advantages of working with truth values in logic. In the second part I look at several cases in which logics involve, as part of their semantics, quantification over a silent parameter, such as modal logic's quantification over worlds. In many cases, this facility produces truth values for sentences which seem neither true nor false by ``supervaluation,'' that is, by ``quantifying out'' the extra, silent argument. Logics that generate truth values for the neither-true-nor-false in this way exhibit striking differences. I consider the following: open sentences in first order logic, vague sentences, ambiguous sentences, paradoxical sentences, and future-tensed sentences in indeterministic tense logic.

Please note that this newsitem has been archived, and may contain outdated information or links.