From wikipedia:
Confirmation bias (also called confirmatory bias or myside bias) is a tendency for people to favor information that confirms their preconceptions or hypotheses regardless of whether the information is true. As a result, people gather evidence and recall information from memory selectively, and interpret it in a biased way. The biases appear in particular for emotionally significant issues and for established beliefs.
David Brooks believes it’s the underlying problem in the US.
The ensuing mental flabbiness is most evident in politics. Many conservatives declare that Barack Obama is a Muslim because it feels so good to say so. Many liberals would never ask themselves why they were so wrong about the surge in Iraq while George Bush was so right. The question is too uncomfortable.