ABSTRACT
Party systems have traditionally been the fundamental variable of political analysis (Duverger [1954] 1969, Lijphart 1984, Sartori 1976). On the basis of the party system of a country (roughly speaking, the number of parties in parliament and the ideological distances between them), one expects to see systematic differences regarding the relationship between parliament and government (executive dominance) as well as differences in the nature of politics (for example, whether the system is polarized or moderate). Recently, an alternative middle-range theory was proposed. According to this theory, the fundamental political differences between countries are generated by the number of veto players (individual or collective actors whose agreement is necessary for a change of the status quo) (Tsebelis 1995a, 1995b).
