Right! More generally, I claim that if a modal agent provably cooperates (in PA) against some other agent, then it cannot provably defect (in PA) against any other agent: roughly speaking, PA can never prove that any proof search in PA or higher fails, so a modal agent can only provably (in PA) do the action that it would do if PA were inconsistent.
Right! More generally, I claim that if a modal agent provably cooperates (in PA) against some other agent, then it cannot provably defect (in PA) against any other agent: roughly speaking, PA can never prove that any proof search in PA or higher fails, so a modal agent can only provably (in PA) do the action that it would do if PA were inconsistent.