We're accustomed to thinking of liberalism and conservatism as parallel ideologies, with conservatives preferring less government and liberals preferring more. The equivalency breaks down, though, when you consider that liberals never claim that increasing the size of government is an end in itself. Liberals only support larger government if they have some reason to believe that it will lead to material improvement in people's lives. Conservatives also want material improvement in people's lives, of course, but proving that their policies can produce such an outcome is a luxury, not a necessity.
The contrast between economic liberalism and economic conservatism, then, ultimately lies not only in different values or preferences but in different epistemologies. Liberalism is a more deeply pragmatic governing philosophy--more open to change, more receptive to empiricism, and ultimately better at producing policies that improve the human condition--than conservatism.
