the logic lies in the fact that an unborn baby hasn't done any harm to anyone AND has the potential to do great things (even mediocre is fine by me, actually).
A criminal, on the other hand, has robbed someone else of his/her right to live(not to mention those who kill many others. Usually they show inhuman cruelty and brutality, and will continue with their evil deeds unless someone stops them.
That's my logic, and I'm sticking to it, whether I'm a hypocrite or not!!