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G. Leigh:
"Stratified Truth";
Vortrag: Gothenburg Logic Seminar, Gothenburg, Schweden; 26.10.2016.

New Foundations, NF, is the set theory proposed by Quine in 1937 which permits the construction of many sets prohibited in Zermelo-Fraenkel set theory, including the universal set, { x | x = x } and set of all ordinals. The theory has a simple axiomatisation, namely extensionality and stratified comprehension, the latter being set comprehension for any formula that can be consistently typed. It is natural to ask whether stratification can provide a solution to the truth-theoretic paradoxes. A naive translation of NF as a theory of truth (interpreting sets as predicates and replacing 'x e y' as `y is true of x') is unsatisfactory due to the interpretation of extensionality. In this talk I will present a theory of truth with a purely intensional truth predicate that is equi-consistent with Quine's New Foundations.