"If a man is offered a fact which goes against his instincts, he will scrutinize it closely, and unless the evidence is overwhelming, he will refuse to believe it. If, on the other hand, he is offered something which affords a reason for acting in accordance to his instincts, he will accept it even on the slightest evidence.” — Bertrand Russell, Proposed Roads to Freedom
Over at Rationally Speaking, Massimo has summarized the findings of a recent study which found that political partisans were quick to recognize inconsistencies in an opposition candidate, but slow to notice them in their own candidate. The study also found that while processing these statements parts of the brain which regulate and process emotions were active, but the parts that regulate rational thinking were less active.
This serves as an important reminder, it's not enough to be skeptical of views you disagree with. You must also be skeptical of views you agree with, including your own. Views that you feel most strongly about are often ones that you have the most reason to be suspect of because it is human nature to allow such conviction to substitute for rigorous critical thinking.