Sj. Brams et Pc. Fishburn, WHEN IS SIZE A LIABILITY - BARGAINING POWER IN MINIMAL WINNING COALITIONS, Journal of theoretical politics, 7(3), 1995, pp. 301-316
Riker's 'size principle' predicts that only minimal winning coalitions
(MWCs) will form in n-person zero-sum games that satisfy certain cond
itions. After summarizing the logic of this principle, a model is prop
osed in which n players can be ordered from most to least weighty. Two
different kinds of MWCs are distinguished: those in which every membe
r is 'critical' (member-MWCs); and member-MWCs that have the smallest
weight (weight-MWCs). A member is critical when its defection causes a
n MWC to become losing. A listing of the possible categories of member
-MWCs indicates that their numbers rapidly increase with the number of
players (2, 6, 20, and 116 for n = 3, 4, 5, and 6 players). Three qua
ntitative measures of bargaining power show that less weighty players
may, on occasion, be more powerful than more weighty players. Possible
empirical manifestations of the inverse relationship between weight a
nd bargaining power in parliamentary coalitions and international poli
tics are discussed.