A neglected alternative? Psychological approaches to coalition formation

The formation of multi-party governments is one of the prime examples of coalition formation, and hence it is studied extensively by political scientists. The political science literature on coalition formation is heavily indebted to micro-­economic­ theories­ in­ this­ field.­However,­ social­ psychologists­ too­ have­ been interested in the subject of coalition formation for over 50 years (see for reviews­of­this­literature:­Gamson­1964;­Kahan­and­Rapoport­1984b;­Komorita­ and­Parks­1995;­Murnighan­1978;­Wilke­1985).­Curiously,­with­ a­ few­exceptions­ (such­ as­Gamson­ 1961a)­ this­ literature­ is­ hardly­ known­ among­ political­ scientists­working­on­coalitions,­just­as­social­psychologists­in­this­field­tend­to­ be­ unaware­ of­ the­ political­ science­ literature­ on­ coalitions­ (again,­with­ a­ few­ exceptions,­such­as­Shapley­and­Shubik­1954). This chapter seeks to provide an introduction to the social psychological approach­ to­ coalition­ formation.­Having­ introduced­ the­ dominant­method­ and­ theories as a background, I shall discuss the key structural variables that have been used to test the underlying assumptions of these social psychological theories.­Specifically,­ I­will­ show­how­social­ psychologists­have­ addressed­ (a)­ the­ relation­between­resources­(e.g.­a­party’s­votes­in­a­political­conventions­paradigm)­ and­ power­ (e.g.­ the­ number­ of­ potential­ winning­ coalitions­ in­which­ a­ party­is­needed),­(b)­the­impact­of­the­units­in­which­the­payoffs­are­made­available­ (e.g.­ number­of­ seats­ available­ in­ government),­ (c)­ the­ impact­ of­ payoffs­ earned­or­lost­of­those­who­are­not­members­of­a­winning­coalition,­and­(d)­the­ difference­between­the­typical­setting­that­is­used­in­social­psychology­(i.e.­interindividual­coalition­bargaining)­and­the­more­relevant­setting­of­political­scientists­(i.e.­intergroup­coalition­bargaining).