Hillary Clinton raised a few eyebrows during Monday's YouTube/CNN presidential debate when she described her politics as "modern progressive" rather than "liberal." Jacob Levy, a professor of political theory at McGill University, is troubled by Clinton's adoption of the progressive mantle.

"'Liberal' and 'progressive' are non-identical categories in American political thought," Levy writes, "and we suffer some real impoverishment of political discourse if one replaces the other just because 'liberal' tests badly." Furthermore, "'progressive' as a concept is tied up with a partly inchoate philosophy of history that I'd have thought long since discredited."

Over at Crooked Timber, Henry Farrell of George Washington University points out that Levy's argument rests on a false comparison. "When Jacob talks about progressivism, he talks about it as a political movement; when he talks about liberalism, he talks about it as a tradition within political theory. This rather predetermines his conclusions; if your political ideals are thoughtfulness, recognition of limits, etc., it’s … unsurprising that political theorists are going to come out looking better than politicians and political commentators."

Farrell's point has ignited quite a comments thread.