OpinionJournal: Get Your Priorities Right, A rationalist crusader does the math on global warming - 'Bjorn Lomborg is a political scientist by training, but the charismatic, golden-haired Dane is offering me a history lesson. Two hundred years ago, he explains, sitting forward in his chair in this newspaper's Manhattan offices, the left was an "incredibly rational movement." It believed in "encyclopedias," in hard facts, and in the idea that mastery of these basics would help "make a better society." Since then, the world's do-gooders have succumbed to "romanticism; they've become more dreamy." This is a problem in his view, and so this "self-avowed slight lefty" is determined to nudge the whole world back toward "rationalism."...'