What then is the fundamental difference between a baby 10 minutes before she travels through your vagina, when she is traveling through your vagina, and when she has emerged from your vagina? Basically environment. Is the baby an adult? No. The baby cannot care for itself at all. So it has to be in the proper environment to continue to progress.
The distinction between 13 and 26, generally, is a singular event. It happens once. It is a demarcation between 2 specialized cells secreted by sexually mature humans and a one-celled entity with a human's full complement of chromosomes. The cell membrane also undergoes a chemical reaction at this point to make it distinct from that of an unfertilized egg. This is a cingular event, and the rest is a natural progression from this point.
And no, this distinction is not arbitrary. There is a cingular "event" that has occurred. There is a before and an after. I know some people like to say "what about heart beat", "what about brainwaves". What about puberty? What about voting age? What about college graduation?
As to unfertilized eggs and parthenogenesis, I say so what? We are not bees. In my system, it is logical that an unfertilized egg is just that, and not a very young human.
My other answer, for people who disagree and/or are moral relativists, is that abortion should be legal up to the 163rd trimester because that's when I think you have a soul. If someone pisses me off and are past that, maybe I'll change it to the 180th trimester and practice my new post-birth abortion procedure out on them. /sarcasm
Yes. Word tricks by pro-aborts don't change reality.