Strong Completeness Theorems for Weak Logics of Common Belief

P. MONGIN, L. Lismont

Journal of Philosophical Logics

2003, vol. 32, pp.115-137

Departments: Economics & Decision Sciences, GREGHEC (CNRS)

We show that several logics of common belief and common knowledge are not only complete, but also strongly complete, hence compact. These logics involve a weakened monotonicity axiom, and no other restriction on individual belief. The semantics is of the ordinary fixed-point type