Comparative Advantage How economist Paul Krugman became the most important political columnist in America. By Nicholas ConfessoreThere have always been columnists who, for better or worse, commanded the greatest attention of their day. Think of Walter Lippmann during the postwar consensus, Joseph Kraft during the Vietnam era, or George Will during the Reagan years. William Safire heralded the Clinton backlash of the early 1990s, Maureen Dowd the frothy, decadent latter half of the decade. In much the same way, Paul Krugman, who has written a column twice-weekly for The New York Times since January 2000, is essential reading for the...