Part I
Why exactly do these things make the unborn not human?
That’s a good question. Perhaps pose it to someone who is making that claim? I stated upfront I have no difficulties understanding the species of the blastocyst. What I do not accept is that because it is a very early stage of human being, it is therefore due all the same rights as the adult human mother or any other adult. You need to explain that to me, because I do not accept at all the Catholic ideal of “God’s image” or a human soul.
In addition, how would infant humans be categorized under this objection before the invention of artificial milks?
They would be categorized as
infants, and therefore granted certain legal rights, and recognized as a human capable of homeostasis apart from another human being’s body. As far as feeding infants, it turns out you don’t have to be fed milk from only your biological mother. Many a wealthy family employed wet nurses, who were not infrequently indentured servants or slaves, to use their bodies to feed infants.
I don’t think it’s an accident that the history of human civilization shows a pattern of lessening tolerance for disposal of very early human beings, with abortion being condemned by many but not punished as murder, and even up to abandoning infants or exposing them.
This is pointed out not as an endorsement of infanticide, but to show you that it has always been the case that abortion of very young humans, such as fetuses in early pregnancy, was not equated to outright murder. Because these were never valued as equal to fully functional, independent humans. In fact, it was so common for children under 5 to die, it was an accepted fact of life that parents would likely lose at least one infant, if not several, over the course of a marriage. I think this harsh reality probably affected many early societies and why they sometimes even accepted infanticide. Nature is unforgiving, and it was understood that if offspring were diseased or couldn’t be supported, adults would cut their losses and move on. Very harsh, but their reality was brutal.
I understand Christians have always condemned abortion, and called it “killing.” Have always condemned infanticide as well, which I agree with. But Christians also did not even believe it was a fully ensouled human at conception, until the advent of the discovery of first the ovum, then embryology, all through scientific observation.
I am fully cognizant of the science. But this does not at all tell me that a blastocyst should be regarded morally or legally that they are of the same value. In face, science informs me that while they are the same species, the blastocyst cannot exhibit any of the characteristics that define humanity - as I stated before, the ability to recognize and process stimuli, the ability bond and communicate, the ability to create, reproduce, etc., etc., etc.