Tyme,
The issue of value judgment is what is not scientific. Judging that there is some crucial moral similarity (or not) between a human embryo and what someone did to a female ovum is a value judgment.
To answer the first question, whether I would or wouldn't depends on my moral evaluation of the difference between the two, not on some biological criteria that show that they are the same in some respects.
If you think the science is wrong, you're welcome to try to disprove it, but I think you'll be disappointed. Otherwise you're simply trying to espouse fanaticism, which is what I think you mean by "the kind of objection a religious person makes to killing the embryo." It is objection beyond reason.
Again, you are missing the objection here. The point I'm making is that science does not answer a question about what you should or should not defend; "shoulds" and "oughts" and "goods" are not measurable. That includes shoulds, oughts, and goods that aren't religious in nature-it's a fact, moral evaluation is not something that you can put into a lab and measure.
So when you answer the question of what you would defend, or critique what I would or would not defend, you are not using science or providing anything remotely approaching a "scientific answer."
You just throw up your hands and declare human life as beginning at conception. I at least try to use scientific observations about biology and sociology, and decide how to conceptualize the transition from human cell to human based on that.
Well, one fundamental problem with this theory is that "human life" is a word, and science does not tell you whether or not an evaluative term is properly applied (unless you've already assumed that the word's definition involves certain criteria that are scientific..in which case, you're back to square one, an unscientific assumption.)
"human life" is a label that implies moral judgment. You have to think about what the term means before you can test any particular thing to see if fits the definition. This would be the question we're addressing here-whether it properly applies to a human embryo or not. Your decision that scientific examination of the development of embryos should inform whether or not we declare "human life" at this stage or that is every bit as arbitrary as saying "human life begins at conception."
My belief that a human embryo is a human being is certainly not scientific-but neither is any claim that it isn't a human being. It's a decision you make at the level of defining the word, not at the level "evidence of this or that quality." So all the technical data in the world won't get you anywhere in a discussion with someone who doesn't accept the arbitrary presumption that comparisons to other biological life forms are the only way to define "human life"...and rightly so.