London has become the place where Republican presidential aspirants go to show us how intellectually-bankrupt their party is. Mitt Romney famously offended the entire United Kingdom by casting doubt on London’s preparedness for the 2012 Olympics; this year, Louisiana Governor Bobby Jindal was first to fall on his face there by condemning imaginary Muslim ‘no-go’ zones, followed by New Jersey’s Chris Christie tripping over a question about vaccinations.

Now, Wisconsin Governor Scott Walker has dodged a question about evolution under the shadow of Big Ben.

Speaking at the Chatham House foreign policy think tank London, Walker was asked: “Are you comfortable with the idea of evolution? Do you believe in it?”

“For me, I am going to punt on that one as well,” he said. “That’s a question politicians shouldn’t be involved in one way or another. I am going to leave that up to you. I’m here to talk about trade not to pontificate about evolution.”

The question was even framed just the way culture warriors like it — as a subjective inquiry into ‘belief’ rather than an objective question of scientific fact. Yet Walker ducked the query like a flying shoe because there is no safe answer for him. If he acknowledged that millions of fossils collected around the world form a strong body of empirical evidence for natural selection, Walker would surely offend the creationists, apocalypse-mongers, and Christofascists who insist on ideological purity in their Republicans. But if he projected doubt on the biological origin of species, Walker would get pummeled for promoting unscientific nonsense.

Tellingly, Walker is more upset by the media talking about anti-science conservatives than the idiotic things his fellow Republicans actually say:

The governor even lamented the media’s polarizing role in the U.S., pointing to recent press coverage of Christie’s vaccine comments as an example of reporters’ attraction to controversy over substance.

“There’s this almost magnetic thing where they go to whatever’s the most glaring headline,” Walker said, after declining to pass judgment on Christie’s remarks.

Walker can’t even manage a note of disagreement on vaccinations because libertarians dislike the ‘cultural Marxism’ of scientific terms like “herd immunity,” while the religious zealots think Gardasil will make their daughters into freewheeling sluts. Those are the two most powerful constituencies in the GOP; Walker can’t afford to annoy either of them, so his public statements on mandatory vaccinations for schoolchildren are just a great, big nothing about states’ rights.

But we shouldn’t lose focus on the real problem here, which is not that Republican politicians pander to their base, but that said base has become more polarized, irrational, and extreme. The word ‘conservative’ has lost its meaning for the conservative movement, which has far-exceeded William F. Buckley’s call to “stand athwart history yelling Stop” and now seeks to radically reverse history to the 19th, 18th, or even the 11th Century. When Scott Walker touts faith-based budgeting for his state, he’s actually responding to the nature of the political environment that he inhabits.