Where's My Liberal Conspiracy?

I'm not one to buy into the smug pronouncements Jonah Goldberg hands down venerating the deep philosophical roots of conservatism and the Vulcan mind-meld each young Republican performs with Burke and Kristol, but, if nothing else, it's certainly true that the conservative ideology is treated as a topic more worthy of study than its liberal counterpart. While browsing Amazon last night, I stumbled upon a whole galaxy of books detailing the movement's intellectual evolution: The Conservative Intellectual Movement in America, The Right Nation, The Conservative Mind: From Burke to Eliot, A Time for Choosing, and so forth. Believe me, that's barely a partial list. Meanwhile, nothing similar seems to exist for the liberal side of the divide, with the closest analogue I could find being James Weinstein's lonely exegesis of American socialism, The Long Detour.

So what's going on here? Rawls, Dewey, Niehbur, Schlesinger, Locke...there's a plenty long development to track, but nobody seems interested in doing the spadework. Is that because, unlike Burke and Kristol, Rawls and Dewey are philosophers studied unto themselves rather than as cogs in the development of a certain thought system? Am I just not finding the books I'm looking for? C'mon all you liberal philosophers in the blogosphere, enlighten me on why I can't enlighten myself.