Evolution has long generated bitter fights between the left and the right about whether God or science better explains the origins of life. But now a dispute has cropped up within conservative circles, not over science, but over political ideology: Does Darwinian theory undermine conservative notions of religion and morality or does it actually support conservative philosophy?

On one level the debate can be seen as a polite discussion of political theory among the members of a small group of intellectuals. But the argument also exposes tensions within the Republicans’ “big tent,” as could be seen Thursday night when the party’s 10 candidates for president were asked during their first debate whether they believed in evolution. Three — Senator Sam Brownback of Kansas; Mike Huckabee, former governor of Arkansas; and Representative Tom Tancredo of Colorado — indicated they did not.

For some conservatives, accepting Darwin undercuts religious faith and produces an amoral, materialistic worldview that easily embraces abortion, embryonic stem cell research and other practices they abhor. As an alternative to Darwin, many advocate intelligent design, which holds that life is so intricately organized that only an intelligent power could have created it.

Yet it is that very embrace of intelligent design — not to mention creationism, which takes a literal view of the Bible’s Book of Genesis — that has led conservative opponents to speak out for fear their ideology will be branded as out of touch and anti-science.