Mary said: 
“One argument I will use against pro-lifers is that they are being dishonest with themselves when they say that a fetus is equal to a person. I say, "let us assume that a first-trimester fetus has equal value with a 9-year-old girl." If this is true, then the nutjobs who blow up abortion clinics are right. All of us would agree that violent force to stop the murder of a 9-year-old girl is justified. (In fact, we would say that non-action would be immoral.) My point: pro-lifers CAN'T have it both ways.”

My response:
Nah, I totally disagree on this one. The murder of the 9-year-old is illegal, and civil law gives us the right to use force to protect her. That’s not the case with abortion.

I heard about Dr. Tiller’s murder through a text message I received at church. (I don't usually check text messages at church, but my wife wasn't with me that day and I was getting repeated messages, and wasn't sure if there was something wrong at home.) When I read what happened to Dr. Tiller, I was devastated. Not only did I know the pro-life movement at large would take a major hit because we’d all be connected to that whackjob, I also knew that a doctor had just been murdered in his church in front of his family. Doesn’t matter what he did. That’s tragic. That man fully believed in the work he did, and the work he did was legal. (albeit there seems to be some evidence that he willfully bent the rules in some situations.)

I debated some fringe "pro-lifers" that were defending Tiller’s murder in the weeks after, and they often had this argument similar to your analogy of the 9-year-old. It was like, if this guy has kidnapped a child and is threatening to murder her, we would applaud whoever heroically jumped in, killed the kidnapper and saved the day. (I’m paraphrasing because I don’t care to go back through Facebook archives to find their actual quote. I eventually blocked them.) My response was, “what do you think we have, a pro-life militia? If the scenario you’re painting happened, we have a trained police force, SWAT teams, even the military gets involved sometimes. Why would some pro-life vigilante need to pull a ‘Batman’ and save the day?” (Ironically, perhaps one of the bad things about movies like Batman is that it glorifies vigilantism.)

Many abortion advocates argued that for pro-lifers to be consistent, they would HAVE to attempt attacks like this on abortionists. What they failed to recognize is that a scenario similar to the situation above DID happen: A woman in Florida named Terri Schiavo was starved and dehydrated after the family lost a court battle. According to some doctors, Terri died a painful death in that 14 day process. Did you see pro-life vigilantes killing the doctors or Terri’s husband in an effort to save her life? No. We lost the case. That’s it. It’s sad. But we lost. So we attempt to educate and move on, so that things go better next time.

Two wrongs don’t make a right. Lives were not saved by Dr. Tiller being killed. Other abortionists will take his place, and already are. Even if lives were saved, it wouldn’t make what that freak did moral.