In this paper we show that in a simple spatial model where the government is chosen under strict proportional rule, if the outcome function is a linear combination of parties' positions, with coefficient equal to their share of votes, essentially only a two-party equilibrium exists. The two...

In this study, we implement a series of voting games in the laboratory to test whether a strategic voting behavior in a proportional system would arise and induce a two-party system. In each voting game, a finite number of subjects with single-peaked preferences, uniformly distributed on a...