Tacit Consent to Pregnancy? No!

This short commentary raises an excellent question about the "if you have sex, you're consenting to pregnancy" argument against abortion rights.

According to many pro-lifers, when women consent to sex, they thereby consent to (and commit themselves to) bearing any resulting children. And so, in deciding to having sex, these women have in effect voluntarily waived their right to get an abortion.

Now, I find this pro-life claim utterly baffling: consent to sex is clearly different from consenting to anything further, many women deliberately use birth control to avoid pregnancy, many women plan on getting an abortion if they should end up pregnant, etc. According to this pro-life claim, it seems, we are supposed to interpret the act of consensual sex itself as involving some sort of mysterious tacit consent and occult commitments that are not only morally significant, but so overwhelmingly morally important as to completely override the actual preferences of the woman. I don't think actions carry occult commitments, and this all seems like superstition to me.

But here's my question. Let's suppose for the sake of argument that actions do carry occult commitments. Even granting this, we still need a way of telling what those commitments are. Without a method of interpretation, we're utterly in the dark. For example, a typical pro-lifer might say that the act of consensual sex carries the commitment to bear the child, waiving one's right to an abortion. But a more radical pro-lifer might say that the act of consensual sex carries the commitment to bear and raise the child, waiving one's right to an abortion as well as one's right to put the child up for adoption. My question is: how are we supposed to tell which interpretation is correct, and which occult commitments are (and are not) carried by the act of consensual sex?

Ultimately, all arguments against abortion rights -- including the argument from tacit consent -- depend on the claim that the fetus has a right to life.  Ari Armstrong and I refuted that argument in our 2010 policy paper, The "Personhood" Movement Is Anti-Life: Why It Matters that Rights Begin at Birth, Not Conception.  If you've not yet read it, be sure to check out the section on "Individual Rights and Abortion."

That being said... over the past few months, I've been thinking off and on about how to defend abortion rights in a way that's more persuasive than the standard pro-choice arguments, including the better arguments of Objectivists.  I want to find a way to make my own view resonate better with reasonable people of the "but it's a baby!" mindset.  So if you have any thoughts on more effective rhetoric on this issue, I'd be interested to hear that in the comments.  I'd be particularly interested to hear from people who switched from "pro-life" to pro-choice views: What convinced you?