Do you honestly see no difference between a mature mind capable of making rational decisions and one formed only in the womb?
Though maybe I've been naive.
Of course I see a difference. A mature mind is formed, in part, by experience. A mature adult has infinitely more experience than a fetus in the womb. The human value of each of our lives is based upon many things but the most significant is what we have contributed and based upon that, what more we may potentially contribute. The spiritual value of our lives is equal but we are not yet expressing that very well.
We live in a relative world. In combat sometimes it is necessary to make decisions such as which of two critically wounded men gets the last spot a med-evac helicopter. You have considerations such as who is most valuable to your unit and/or who has the best chance of survival. You have to make those decisions with incomplete information often under severe distress. An important factor here is who makes that decision. It is not a commander somewhere up the chain of command, it is not the helicopter pilot, it is not a group decision by those who are left; it is decided by the one who has responsibility for that unit.
It is that type of experience that leads me to believe that if you do your best to make an honest decision about your family or whatever, it is not my responsibility to force my moral belief upon you and take away your right and responsibility to make that decision. And that goes for everyone else not directly connected with your situation.
If you want a subtle distinction, there's this problem with a certain type of murderer ~ usually they've killed more than once. If you put them in prison for life they're going to kill someone else ~ a guard, a white collar criminal, a visitor maybe.
If you execute them, that won't happen.
The statistics give the probability of their killing someone else at more than 100% because some of them kill two or three more times while in prison.
The right to life type who thinks not executing such murderers is a wise course simply ends up being instrumental in the murder of one or two otherwise innocent people.
Obviously not everyone who murders is going to be a stone-cold, multiple murderer in prison, but it is wrong to NOT execute such folks early in their career.
That is, the correct right to life position is to execute the worst murderers, and we arrive at that conclusion by discovering the innocent people we would otherwise condemn to death.
I think you can do the same sort of analysis in dealing with abortion and war.