Rougier was also a political philosopher in the liberal tradition of Montesquieu, Constant, Guizot, and Tocqueville. Consistent with his conventionalist epistemology, Rougier believed that political power rests not upon eternally valid claims, but upon conventions that he called "mystiques". The only possible reason to prefer one political system over another, he believed, depends not on eternal truths but on purely pragmatic grounds. In other words, political systems should be chosen not based on how "true" they are, but rather on how well they work.