Jacob Weisberg asks: Birtherism, the debt ceiling, climate change, evolution: Are Republicans losing their grip on reality?

At a press conference last week, someone asked Chris Christie for his views on evolution vs. creationism. “That’s none of your business,” the New Jersey governor barked in response.

This minor incident, which barely rated as news for a few political blogs, offers a glimpse of Christie’s personality, which seems increasingly grumpy and snappish. But it says even more about the current state of the national Republican Party, where magical thinking trumps rationality, and even to acknowledge basic realities about the world we live in runs the risk of damaging one’s political future.

Christie is not part of the natural constituency for Darwin-denial. He’s an intelligent man, a lawyer, a fiscal rather than a social conservative. But Christie is also someone who might want to run for president someday, or be selected as someone’s running mate. For those purposes, he must constantly ask himself the question: Am I about to say something to which a white, evangelical, socially conservative, gun-owning, Obama-despising, pro-Tea Party, GOP primary voter in rural South Carolina might object? By this standard, simple acceptance of the theory of evolution becomes a risky stance. To lie or to duck? Christie chose the option of ducking while signaling his annoyance at being put in this ridiculous predicament.