Not a rhetorical exercise, especially not today. And not for the theocon journal First Things, which took up the question in seriousness in 1994 following Paul Hill’s killing of an abortion doctor in Florida. Hill said in his defense, “Whatever force is legitimate in defending a born child is legitimate in defending an unborn child.” Many would second that, and have.  

Read “Killing Abortionists: A Symposium.” It has some weird coding at the top, but you can scroll down to the various opinions. Robert George’s is a good bit more snarky that his statement today after the Tiller killing, as he compared killing abortion docs to supporting abortion rights:

“I believe in policies that reduce the urgent need some people feel to kill abortionists while, at the same time, respecting the rights of conscience of my fellow citizens who believe that the killing of abortionists is sometimes a tragic necessity-not a good, but a lesser evil. In short, I am moderately pro-choice.”

I suppose that’s one approach.