Giacomo  Bonanno Department of Economics University of California Davis, CA 95616-8578   USA e-mail:  gfbonanno@ucdavis.edu  http://www.econ.ucdavis.edu/~bonanno	Klaus  Nehring Department of Economics University of California Davis, CA 95616-8578   USA e-mail:  kdnehring@ucdavis.edu http://www.econ.ucdavis.edu/~nehring

The logic of common belief does not always reflect the logic of individual beliefs. In particular, the Negative Introspection property (axiom 5) fails at the common belief level, that is, it can happen that neither is A commonly believed nor is it common belief that A is not commonly believed. Indeed Negative Introspection of common belief involves restrictions on individual beliefs of an intersubjective nature. We consider a number of interpersonal restrictions on beliefs and study their relationship. We also provide a characterization of  Negative Introspection of common belief in terms of interpersonal properties of individual beliefs. All the results are proved syntactically.

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