Again sir, I respectfully disagree.
At least we're able to stay civil, one more beneficial fallout from you and I and Greymare having actually met face-to-face and had a good time together.
Once combined the "potential" is now "kinetic" and developing.
I don't know what you mean by "kinetic": the actual meaning of the word is just "moving" (and the ovum is every bit as motile as the zygote; and the spermatozoon, of course, much more motile than either) but I'm sure you intend something more.
The character traits are in place
No, no, no, they're NOT. Not even such a basic trait as "individuality" is in place: through the morula and blastula stages (until cell differentiation sets in during the gastrula stage), twinning can happen-- and unhappen.
the intelligence potential is in place and developing
No, no, no, most especially there is no sign of "intelligence" yet, nor does any development toward it start for quite a while.
In short, once Spermatazoa and ovum combine, the architectual plans are complete
An architectural plan is not a building. We strongly distinguish between demolishing a building, for which a permit would certainly be required, and putting a blueprint on the shelf, which you might feel some pangs about, if you have invested a lot of forethought into it and then find you can't go through with the project, but certainly you still have every right to change your mind without having to ask permission from anyone else.
and the materials to finish the job are present
No, no, no, very little of the necessary material is present. The mother has to supply the material, if she is willing (or compelled) to do so. You are aware that God Himself aborts most embryos? Either the zygote fails to implant, or the implantation fails to take, in the majority of cases. Should the woman be required to supply the zygote with material to become a person? It isn't a person yet, so saying that the zygote has a "right" to develop is, to my mind, a totally wrong-headed way to look at it (the zygote doesn't WANT anything yet, doesn't CARE whether it develops or not; it doesn't have anything to "want" or "care" with). And saying that we have a duty to turn every potential person into an actual would seem to imply that we should never allow a woman to forego sex and thereby "murder" the innocent ovum through intentional menstruation (women should have to stay pregnant as continuously as they are able, conceiving again within a month or two after every birth).
Whether or not there is a "spirit" (perspective occupant of the dwelling), present...well opinions vary on the matter. And that is really what this all boils down to.
Well, if there is a "spirit" hanging around the zygote, it doesn't DO anything! It doesn't have anything to do with "personality", so why is it of any moral concern? Let me give you some puzzles to work on: some zygotes eventually develop, not into one person, but into two (or more: but let us just consider the identical-twin case first). Does God supply that zygote, right from the beginning, with two souls, which both hang around the same cell until they can go their separate ways, or does he wait to supply the second soul until after the separation? How about the case where a morula separates into two, which separately implant-- but then fuse back into one (this is in fact what happens with most incipient twinnings)? And here's the weirdest case: women sometimes double-ovulate, and if both are inseminated, this can result in fraternal twins (not genetically identical), or, sometimes they will fuse, giving a "chimera" with the cells in different patches of tissue having non-identical genomes (James Buchanan is probably the best-known human chimera: among his many distinctive traits, he was the only President of the United States whose eyes were of different colors). Do the zygotes start off with two souls, which also "fuse" (how do spiritual entities go about fusing)? Or does God foreknow the outcome, and always supply the right number of souls for the number of people that will result? In that case, wouldn't God know in advance when a zygote was never going to end up a person, and refrain from supplying a soul to start with?
That it is a living human body is not in question.
Yes, yes, and a blood cell is "living", and "human", and a "body"; that is not in question either. In theory we can keep it alive on a Petri dish indefinitely; but we do not feel any moral compunction to do so, and would laugh at the thought that cleaning up a bloodstain is an act of "murder", because although it is a "living human body", it is most decidedly not a "person", and has none of the traits that we morally value. The difference between a blood cell and a zygote, of course, is that the blood cell has no
potential to become a person (unless our cloning technology vastly improves? will we then be under obligation to actualize every potential person that we possibly can?), but until there is an
actual person, I don't see the moral obligation that you do.
Is anyone home? That is the question. When does the human body become a human being?
When does it acquire "personality" or "psyche"? At least in the minimum sense of ability to perceive and act? That is an empirical question, whose answer is not all that mysterious: starting around four months, sometimes a little earlier, the neural net rather abruptly turns on, an event known since ancient times as the "quickening" and considered in modern terms the point at which we stop talking about an "embryo" and start talking about a "fetus" (the fetus has senses, and while it may not be able to "do" very much, it does swim around and give the mother little kicks). Thomas Aquinas was of the opinion that this is when the "soul" attached; and the legal systems made distinctions between abortion before and after this point ("Abortion prior to quickening can never be the subject of indictment under the common law" -- Blackstone's Commentaries, a widely relied-upon 18th-century summary). This used to be the common Christian attitude: the notion that abortion should be forbidden from the moment sperm-hits-egg is a recent "conception".
There is of course some difficulty about the question because there is no black-and-white line. Neurons are distinguishable as a class of differentiated cell from about one month, and start to have flashes of electrical activity long before they start acting as a coherent nervous system; I speak of the "quickening" as a "rather abrupt" event, but of course that does not mean "instantaneous".
The Bible gives a pretty strong inuendo to that question when the Lord is noted in saying "I knew you before you were stitched together in the womb".
This says that the Lord knew Jeremiah prior to
conception. It is talking about divine foreknowledge from the beginning of time. I'm sure you have had pointed out to you before (if not, I'll look it up again, but I don't have the cite right now) the passage where, if a miscarriage is the result of violence against a pregnant woman, a fine will be imposed: it is unambiguous that the Bible did not regard the death of an unborn child as a case of murder or even manslaughter.
To a woman who does not want a child, the baby may or may not exist until it is living, breathing on its own and opens it's fathomless eyes to look into hers...that is shock reality.
In 90% of abortions, we are dealing with an insensate blob which doesn't HAVE any "eyes", either literally or figuratively. I agree with you that after the first trimester (when the fetus has some degree of "psyche", at least enough to feel pain), there starts to be a moral issue.
How ironic that we treat criminals on death row with more respect than we do a "human form" still trapped in the placenta, but guilty of nothing but existing and growing, and being dependent on its "host", through no "choice" of its own...
It can't be "guilty" of anything, or make any "choice", because it doesn't have anything to CHOOSE with! It is still more analogous to the "human form" of a bloodstain, than to a "person" of any kind.