From the comparative literature on legislative organization, we identify three factors to explain this trend: partisan sorting, electoral incentives and negative agenda control. Our empirical analysis shows that intraparty conflict is primarily explained by the opposition between Anglo-Celtic/Protestants and French/Catholic members of Parliament. Once lawmakers sort into parties according to their religious affiliations, we observe a sharp increase in voting unity within the Liberal and Conservative caucuses. Ultimately, our results highlight the importance of territorial and socio-cultural conflicts, as well as agenda control, in explaining the emergence of parties as cohesive voting groups in the House of Commons.
Canadian Journal of Political Science 2013, vol. 46(4): 773-797.