Irreconcilable differences

Over at National Review's "Corner", Jim Manzi supposes that ideological differences between Conservatism and Libertarianism can be improved through a pragmatic fusing of sorts. There's a fundamental reason this is a terrible idea: Those who are to the left on political spectra generally are pragmatic in theory, ideological in practice. Their experiments, begun by Karl Marx and other thinkers, ended with the Holocaust, the Gulags, the Red Guards, etc. Those on the right are ideological in theory, pragmatic in practice. It is for this reason that conservatism, a foundation of thought that moves society ever rightward with net positive consequence, will last indefinitely. And I know I'm right, largely because Liberal Fascism, regardless of ones' opinions, has been flying off the shelves.