In colonial America, conventional wisdom held that women could not get pregnant unless they enjoyed the sex.

People, who would have thought I’d have an opportunity to bring up this factoid right in the middle of a presidential race? Thank you, Rep. Todd Akin of Missouri! Without you, we might have been condemned to spend today reinvestigating the Congressional Budget Office Medicare cost projections.

But, instead, we are going to deconstruct the now-legendary explanation from Akin of how, in cases of “legitimate rape,” women’s bodies will “shut that whole thing down” before pregnancy occurs.

Akin, a U.S. Senate nominee, has a reputation for, shall we say, thinking outside the box. It was not for nothing that the incumbent, Claire McCaskill, had targeted him as the Republican I’d Most Like to Run Against. McCaskill was particularly attracted by his comparison of federal student loans to “Stage 3 cancer.” And then there was his vote against the school-lunch program.

But all that paled next to his anti-abortion disquisition during a recent TV interview. In very few words, Akin managed to make three points. One was that rape victims can’t get pregnant. This theory goes back to our forefathers, who believed that in order for our foremothers to conceive, “the womb must be in a state of delight.”

“They never asked the women,” said Margaret Marsh, the co-author of The Empty Cradle, a history of infertility in America.

The idea never entirely faded away, possibly because it reflects so well on male lovemaking prowess. (Failure to conceive, by the same rule, was all because of female frigidity.)

Since Akin’s debacle, we’ve learned that a former member of Congress once told the House Appropriations Committee that when people “are truly raped, the juices don’t flow, the body functions don’t work and they don’t get pregnant.” And that James Leon Holmes, a federal judge currently hearing cases in Arkansas, once said that “concern for rape victims is a red herring because conceptions from rape occur with approximately the same frequency as snowfall in Miami.”

This line of thinking is also familiar to David Wiley, a professor of health education at Texas State University who co-authored a study on what Texas school districts were actually teaching their students in sex education classes. (He was inspired, he said, when “a sincere male student asked aloud, ‘What is my risk for cervical cancer?’ ”) Searching through the websites of groups that were providing program material to the districts, Wiley found one that announced: “If the woman is dry, the sperm will die.”

So the first part of Akin’s comment is not the product of his unique imagination. It’s still being repeated all over the country, perhaps out of veneration for the thoughts of the founding fathers.

Part two was Akin’s mention of “legitimate rape.” This is the piece that had every mainstream Republican honcho in the country calling on Akin to drop out of the race. Karl Rove pulled the plug on his money.

Paul Ryan reportedly got on the phone and begged Akin to go away for the good of the team. (The team, or at least the Paul Ryan part of it, had once sponsored anti-abortion legislation with Akin that referred to “forcible rape” in the same cringe-inducing fashion.)

But it’s the third point in Akin’s comment that’s really important for this election. Before he got sidetracked into colonial-era biology, the veteran House member was trying to explain why he opposes abortion even in the case of rape. “But let’s assume that maybe that didn’t work or something,” Akin said, referring to the miraculous female shutdown mechanism that he’d discovered. The rapist, he continued, should be punished, but not “the child.”

This is a perfectly consistent theological doctrine. If you believe that every fertilized egg is a human being, with the same sacred rights as a newborn baby, then, obviously, you are not going to want it to be aborted, no matter how it came into the world.

Politicians who say they oppose all abortions are making perfect sense, except for the part where they try to impose their doctrinal beliefs on the vast majority of the country, which does not share that particular religious conviction. It’s the abortion-except-for-rape-and-incest position that doesn’t compute. Rape victims, yes, but not a 14-year-old who was impregnated by her 15-year-old boyfriend? The impoverished mother of six kids whose birth-control method failed? There’s no way to set the worthy-of-compassion bar unless you trust women to set it for themselves.

Maybe Akin’s real sin is that he exposed the phoniness of the rape-and-incest exception, which is just an attempt to make radical extremism look moderate. That and the theory of the delighted womb.