Ramesh – I agree with your point (and many of Engel’s). But I’d also add that he leaves a lot out of the historical evolution of the word liberal. By the time FDR was president, never mind JFK, “liberal” had already changed profoundly and was characterized more by a faith in positive, largely economic, rights (think of FDR’s “second bill of rights”). The Civil Rights movement was in an important sense a return to a liberalism grounded in traditional understandings of the word — which is what gave it much of its moral authority; it was consistent with the best principles of the Declaration of Independence etc.

But as almost any leftwing academic will tell you today, many of the leaders of the civil rights movement, starting with King on down, believed in “economic justice” and the whole suite of positive rights that come with such things. Almost invariably that is the “unfinished legacy” of MLK they refer to. And because that agenda involves a liberalism-in-name-only which really means statism it hasn’t been nearly as popular.