"Many pro-choice activists argue quite compellingly that personhood is not conferred at the moment of conception. Some contend that personhood comes sometime later,..."
For a self-proclaimed philosopher, you are very sloppy in your language. While pro-choice activists freely aver that personhood does not occur at conception, I have yet to hear anything in the way of coherent argument, compelling or otherwise.
For example, if a fetus is not a person at conception, but achieves personhood later, what is the event or process that occurs which conveys personhood onto the fetus? What is it about the fetus that will allow us to examine it and decide, "No, that is not yet a person," or ""Yes, this one has become a person?" You ask similar questions yourself. But you provide no answers, only imply that anti-abortion agumentation is wrong. Anything in the way of an argument would at least attempt to answer questions such as these.
Which I don't believe is even possible.
This conversation is taking place in a biological context (fetus, cells). The word "person" has no biological meaning; it is simply not a biological term. "Person" only has meaning in a moral, political or sociological context.
But, I'm always willing to concede that I may be missing something. If you know such an argument, and you claim to know at least one that makes a "compelling" case, we would be much obliged if you would share it with us.