1. GL and other systems of propositional modal logic 2. Peano arithmetic 3. The box as Bew(x) 4. Semantics for GL and other modal logics 5. Completeness and decidability of GL and K, K4, T, B, S4,… Expand

0. Introduction.- 1. The Incompleteness Theorems.- 2. Self-Reference.- 3. Things to Come.- 4. The Theory PRA.- 5. Encoding Syntax in PRA.- 6. Additional Arithmetic Prerequisites.- I. The Logic of… Expand

What is one to make of a paper on syllogistic inference whose authors suppose that “All A are B; no B are C; therefore, some C are not A” is a valid form of inference (cf. Johnson-Laird and Bara,… Expand

Part 1 Studies on set theory and the nature of logic: the iterative conception of set reply to Charles Parsons' "Sets and Classes" on second-order logic to be is to be a value of a variable (or to be… Expand

The Unprovability of Consistency is concerned with connections between two branches of logic: proof theory and modal logic. Modal logic is the study of the principles that govern the concepts of… Expand