(Update: Called it.)

The Joe Walsh swing-voter alienation train rolled on last night, as he declared during his WTTW debate with Tammy Duckworth that he's against abortion under any circumstances. Which may be politically unwise, but it's his ethical stance, and he's sticking to it, which is fine and fair enough: better that he not talk around an absolutist position than fumble through a dodge. Strictly speaking, that's the line of the Catholic church (emphasis mine):

Far less pressure has been applied to the point at which the Ryan approach differs from Catholic teaching. Mr. Ryan said he couldn’t “see how a person can separate their public life from their private life or from their faith,” and then narrated the transfixing power of that first ultrasound. So far, so Catholic. But then came the focus-group-tested political answer: the policy of a Romney-Ryan administration would be “to oppose abortion, with the exceptions for rape, incest, and life of the mother.”

[snip]

The church’s staunch position on fetal personhood was on display two years ago in Phoenix, when Margaret McBride, a nun on the ethics board of St. Joseph’s Hospital, authorized an emergency abortion to save the life of a dying woman. Sister McBride was automatically excommunicated by her bishop (though later reinstated quietly). Mr. Ryan’s new position unites him with Sister McBride in defending the threatened life of a pregnant woman.

OK, so not strict strict. 

After the debate was when things really went haywire. Not many Republicans are unwilling to make exceptions for the life of the mother, for fairly obvious reasons. But they're not as obvious if you think exceptions for the life of the mother aren't scientifically necessary: "with modern technology and science, you can't find one instance… there's no such exception as life of the mother, and health of the mother, same thing."

As Rich Miller points out, this puts Walsh in conflict with "staunchly pro-life groups." But not with all of them. For instance, this is from one of the groups Miller links to (emphasis mine):

Abortion is never necessary to save a woman’s life. Four hundred and eighty physicians have signed a public declaration stating: “I agree that there is never a situation in the law or in the ethical practice of medicine where a preborn child’s life need be intentionally destroyed by procured abortion for the purpose of saving the life of the mother.”

See how that works? The absolute "abortion is never necessary" becomes "intentionally destroyed by procured abortion." The statement's a bit longer than that, and includes "A physician must do everything possible to save the lives of both of his patients, mother and child. He must never intend the death of either." The simple answer is that a doctor cannot perform an abortion (or a "procured abortion," or "theraputic abortion," depending on the phrase), but medical treatments that have "abortifacent effects" are okay:

Another example: if a mother has life-threatening seizures that can only be controlled by medication that will kill or severely deform her unborn child, the physician will frequently prescribe a therapeutic abortion.  In both of these cases, the abortion is not necessary to protect the mother’s health.  The necessary medication may injure or kill the pre-born child, but this is no justification for intentionally killing the child.  If the child is injured or dies from the medication prescribed to the mother to save her life, the injury was unintentional and, if truly medically necessary, not unethical.

The same goes for, say, radiation therapy. But not all anti-abortion arguments, and advocates, are created equal:

With any serious maternal health problem, termination of pregnancy can be accomplished by inducing labor or performing a cesarean section, saving both mother and baby. If a mother needs radiation or chemotherapy for cancer, the mother’s treatment can be postponed until viability, or regimens can be selectedthat will be better tolerated by the unborn baby. In modern neonatal intensive care units 90% of babies at 28 weeks survive, as do a significant percentage of those at earlier gestations.

The principle is that maximum viability must be preserved, even if it's a matter of days or hours, requiring "perinatal hospice": "For fatal birth defects, abortion is sometimes presented as the only option. But a better alternative is perinatal hospice. This involves continuing the pregnancy until labor begins and giving birth normally, in a setting of comfort and support until natural death occurs."

Then there's ectopic pregnancy, and with it, math:

Percentages are hard to come by, but the BBC News piece on one of the successful deliveries listed above, reports that the baby had a 5% chance of survival, while there was a 10% chance that the mother would die. A 2003 Canadian Broadcasting story on the successful delivery of an ectopic pregnancy in Canada quotes Dr. Robert Sabbah as saying that the baby only had about a 1% chance of survival. Without question, the odds of survival for ectopic babies is extremely slim, but clearly it is erroneous to claim that "there is no way to save an ectopic pregnancy". If more ectopic pregnancies weren't ended prematurely, who's to say there wouldn't be far more examples of successful births?

Of course, we still must give adequate consideration to the mother.

So when Joe Walsh says "medically today, the health of the mother is not a reason for abortion," it's not that Chicagoland's loose cannon is necessarily more absolute than the anti-abortion movement. As with Todd Akin's "legitimate rape," it comes out of political undercurrents that are easy to miss if you're not familiar with the lingo (such as the idea that "abortion" is shorthand for "procured" or "theraputic" abortion). That one word is a needle in a haystack, and on the head are lots of angels.