Ideological parsimony

The theoretical virtue of parsimony values the minimizing of theoretical commitments, but theoretical commitments come in two kinds: ontological and ideological. While the ontological commitments of a theory are the entities it posits, a theory’s ideological commitments are the primitive concepts it employs. Here, I show how we can extend the distinction between quantitative and qualitative parsimony, commonly drawn regarding ontological commitments, to the domain of ideological commitments. I then argue that qualitative ideological parsimony is a theoretical virtue. My defense proceeds by demonstrating the merits of qualitative ideological parsimony and by showing how the qualitative conception of ideological parsimony undermines two notable arguments from ideological parsimony: David Lewis’ defense of modal realism and Ted Sider’s defense of mereological nihilism.