On the logic and role of Negative Introspection of Common Belief

We provide two local characterizations of Negative Introspection of Common Belief (NI). The first shows NI to be equivalent to the conjunction of Truth of individuals' belief about what is commonly believed (TCB) and common belief in TCB. According to the second, NI corresponds to a, general reducibility property of higher-order beliefs about common belief to either common belief or its negation. Negative Introspection of common belief and its characterizing conditions help provide epistemic foundations for game-theoretic solution concepts. We show this for correlated equilibrium under incomplete information as well as backward induction in a class of extensive games. (C) 1998 Elsevier Science B.V.