Edna Ullmann-Margalit provides an original account of the emergence of norms. Her main thesis is that certain types of norms are possible solutions to problems posed by certain types of social interaction situations. The problems are such that they inhere in the structure (in the game-theoretical sense of structure) of the situations concerned. Three types of paradigmatic situations are dealt with. They are referred to as Prisoners' Dilemma-type situations; co-ordination situations; and inequality (or partiality) situations. Each of them, it is claimed, poses a basic difficulty, to some or...