Rachael , I agree with you that everyone should read Justin Elliott's Salon piece debunking conspiracy theories about Sarah Palin's uterine activity. People should read it because it's good, and because Elliott makes Andrew Sullivan look foolish for making false claims about Elliott's work ethic. But don't hold your breath waiting for this excellent case against the conspirancy theory to change anyone's mind. As Chris Mooney reported in Mother Jones , the research shows that people who need to believe untrue things don't respond well when presented with evidence against their beliefs. In fact, often debunking false beliefs caused people who hold them to double down.
Take, for instance, the question of whether Saddam Hussein possessed hidden weapons of mass destruction just before the US invasion of Iraq in 2003. When political scientists Brendan Nyhan and Jason Reifler showed subjects fake newspaper articles (PDF) in which this was first suggested (in a 2004 quote from President Bush) and then refuted (with the findings of the Bush-commissioned Iraq Survey Group report, which found no evidence of active WMD programs in pre-invasion Iraq), they found that conservatives were more likely than before to believe the claim.
While initial research shows less stubbornness in the face of evidence amongst liberals than conservatives (and it's liberals who are more likely to believe Palin conspiracy theories), the evidence is far from conclusive. It may be that researchers just haven't tested a false belief that liberals who hold it are deeply attached to. Perhaps they should test Trig Truthers, because in my experience, Trig Truthers are impervious to any amount of evidence you wield against their claims. When people are attached to a falsehood, the emotional price of letting go of the lie is higher than the price of being seen by others as silly or wrong.
What always interests me about conspiracy theories is what emotional needs lurk behind them. Birthers need to believe that it's impossible for a black son of a non-American man to become president. Anti-vaccination and HIV conspiracy theorists wish to believe that the key to health is avoiding medical science and just relying on what they can personally control in their kitchens. But I'm a little hard-pressed to see why it matters if Sarah Palin gave birth to her own son. The fact that she had an oops pregnancy at 44 flies in the face of the common wisdom that holds that women after 40 can't give birth without massive medical intervention, and I suppose that feeds into it. (I wouldn't be surprised if parents who had to go through IVF are overrepresented in the Trig Truther ranks.)
At its heart, I think the conspiracy theory reflects the belief that Sarah Palin is a phony. Some conspiracy theories are people rolling up what they know or suspect about a person or a system and making unproven links: 9/11 Truther theories are a manifestation of the suspicion that Bush is an opportunist and a liar. Global warming denialists believe that environmentalists are more anti-capitalism than pro-environment. Believing Sarah Palin made up an entire pregnancy is a way to "prove" to yourself your suspicions about a woman who has done a remarkable job of breezing through life by faking it. To my mind, the evidence against Palin on the record should be enough to satisfy a dislike of her--everything from her pretending she reads newspapers to using Alaska's proximity to Russia as evidence of her foreign policy qualifications to her embrace of reality television---but some people just need to believe something more dramatic.