You saw the poll yesterday, I'd imagine, that 64 percent of Republicans still think Obama was born in another country, and that 63 percent still think Iraq had WMD before the invasion. What can one say? As Andrew put it yesterday, it's an "ideological hall of mirrors."
Doing a simple Google search of the phrase "where did wmd go" shows very quickly how so many can take up residency in this hall and stay there, believing only the images they see inside it. Pajamas Media and Free Republic and Michelle Malkin, none of which I'll link to, kept this thing going for a long time. Seems to have mostly petered out now, but I found articles up through 2010 and 2011 latching on to some new piece of "evidence" that "proves" that Saddam's arsenal ended up in Syria. The official posture of the US government, by the way, in the form of the report led by Charles Duelfer, is that Iraq had no WMDs.
It's pretty much down to a formula now. Some Democrat, or The New York Times, or some scientist, asserts a fact. Right-wing blogs and Fox and the Journal "rebut" it with a complicating "fact." Objectivity is thus obscured. Most people simply don't believe that a "news" network would actively lie to them in service of a partisan agenda, which Fox knows and takes full advantage of. Then the rest of the media are forced to acknowledge that there are two sides to an "argument" about an objective fact.
The left--by which I don't mean liberals, but the academic postmodern left, which is a very different thing from liberalism, and if you don't understand that, you might try to go learn something about it; Google "Sokal hoax," for starters, and remember that Alan Sokal was and is a liberal--did start all this way back when, in the 80s. But there was a huge difference.
Back then, the nonsense was limited to some humanities departments and obscure peer-reviewed journals. Poststructuralist philosophers didn't have a "news" network, although life would have been rather amusing if they had. The weather reports alone would have run to hours, on the question of whether you needed your umbrella today (if you get that reference without looking it up, tell us).
The important question before us is, what can ever make Republicans accept a government conclusion (reached by a Republican-appointed commission, no less) or the plain existence of an obvious authentic birth certificate. The answer, I guess, is nothing.