Well, there are a lot of them. But the one I want to take on is Scott Lemieux's. He says that those who would make abortion illegal but do not support serious criminal sanctions against the woman seeking the abortion are in a contradiction, at least if they accept that women have the same moral agency as men.
In one of his comments threads, I argued that this didn't work against abortion opponents who think of abortion as morally wrong, but not as wrong as infanticide, as most do. Other commenters made similar points at greater length.
In fact, most of us combine the following views about something:
*X is wrong.
*X should be legally suppressed.
*Not everyone involved in X should be subject to criminal sanction.
For example, I suspect most Democrats believe that American employers hiring illegal aliens are doing something wrong, and that there should be some legal consequences, while opposing criminal sanctions against the illegal aliens. They are hardly thereby denying moral agency to undocumented Hispanic workers.
There are a lot of prudential and moral reasons that a person might oppose criminal sanctions against women seeking abortions, even if they thought the law should step in more often (my own position) or even all the time (not my position).
Update: Scott responds here.
It's tricky defending views you don't hold, especially on issues it is possible to lose friends over. I'm not a pro-lifer, but I don't think the position of wanting to suppress abortion without criminalizing women who seek them is inconsistent. In addition to the relatively abstract issue of whether a particular argument is a good one or not, there is the problem that seeking to furhter polarize people's opinions on abortion on the grounds of "logic" may not have good consequences.
To address Scott's challenge, I can think of a couple of reasons that a pro-lifer might think criminal sanctions inappropriate:
*Criminalizing something much of a society thinks is permissible is often a mistake, even if that part of society is mistaken about the moral issue. That's basically my view of spanking. I might support criminalizing it if there was a social consensus against it, but I hardly want to drag ordinary parents away to jail when such a consensus doesn't exist.
*Many women seeking abortions do so under conditions of economic or social duress. This would be even more true if abortion was legally unavailable. A person opposed to the legality of abortion could regard this as mitigative, even if not justificatory.