IMPOSSIBILITY THEOREMS FOR NORMAL-FORM GAMES

Two recent papers (Cubitt and Sugden, 1994; Samuelson, 1992) have esta blished impossibility results which cast doubt on the coherence of the assumption of 'common knowledge of rationality'. It is shown that the Cubitt-Sugden result is the more powerful of the two impossibilities. Second, it is proved that the existence of a quasi-strict equilibrium is sufficient to construct sets which satisfy the Cubitt-Sugden axiom s. This fact is used to establish that their impossibility result cann ot arise in 2-player games. Finally, it is shown that if a weak symmet ry postulate is added, a new impossibility result arises for this clas s of games.