Sincerity is so central to the unconstrained [read "progressive"] vision that it is not readily conceded to adversaries, who are often depicted as apologists, if not venal. It is not uncommon in this tradition to find references to their adversaries' "real" reasons, which must be "unmasked." Even where sincerity is conceded to adversaries, it is often accompanied by references to those adversaries' "blindness," "prejudice," or narrow inability to transcend the status quo. Within the unconstrained vision, sincerity is a great concession to make, while those with the constrained [read "conservative"] vision can more readily make that concession, since it means so much less to them. Nor need adversaries be depicted as stupid by those with the constrained vision, for they conceive of the social process as so complex that it is easy, even for wise and moral individuals, to be mistaken—and dangerously so. They "may do the worst of things without being the worst of man," according to Burke.

(Thomas Sowell, A Conflict of Visions: Ideological Origins of Political Struggles [New York: Basic Books, 2002], 57 [brackets added; endnote omitted])

Note from KBJ: Do you understand what Sowell is saying? Progressives are obsessed with sincerity, which they understand as proper motivation. They believe (presumptuously) that only they are properly motivated. Conservatives are motivated by greed and other sinister things, which progressives delight in "exposing." (Exposing sinister interests goes back at least to Jeremy Bentham [1748-1832], who was an early progressive.) Philosophers teach their students that an arguer's motivation is irrelevant to the quality of the argument produced. Many philosophers, sadly, do not practice what they preach. When they hear a conservative argue against, say, homosexual "marriage," they reply that the arguer is a "homophobe," or even a "latent homosexual." What in the world does this have to do with the argument? The answer, of course, is nothing. What this shows is that progressives are not interested in (even if they were capable of engaging in) rational discussion. They view conservatives as enemies to be conquered, not as adversaries to be refuted. It's war, not inquiry. All's fair in love and war. How many times have you heard a conservative question the motives of a progressive? It happens, but not nearly as often as the reverse. I speak as someone who was a progressive for far longer than he has been a conservative.