Towards a Conditional Model of Coalition

This is an attempt to formulate a conditional model of coalition formation. Predictions from this model are tested against data on coalition formation in Dutch local government in 1982. Starting from a simple model of the behaviour of party politicians, it is assumed that the coalition behaviour of partiesdependson the competitiveness of the (local) political system. The choice of a coalition strategy (minimizing size, minimizing policy range or proportional representation) is contingent upon two dimensions of the competitiveness of local politics. These are the amount of electoral volatility and the extent to which local election results follow national trends. Our conditional theory predicts different coalition behaviour in polities differing with regard to these two factors. Though the hypothesis was falsified, a more detailed analysis showed that (local) political competitiveness did make a difference in the choice of at least some of the coalition strategies. These differences, moreover, were in line with what was to be expected from the theoretical model. In the literature on formal theories of coalition formation, a number of distinct theories has been formulated. These theories are normally grouped in two ‘families’, differing with regard to the strategy adopted by parties forming coalitions. First