Self-reference in arithmetic II

Abstract

In this sequel to Self-reference in arithmetic I we continue our discussion of the question: What does it mean for a sentence of arithmetic to ascribe to itself a property? We investigate how the properties of the supposedly self-referential sentences depend on the chosen coding, the formulae expressing the properties and the way a fixed point for the expressing formulae are obtained. In this second part we look at some further examples. In particular, we study sentences apparently expressing their Rosser-provability, their own Σ0n-truth or their own Π0n-truth. Finally we offer an assessment of the results of both papers.