How does it falsify my claim? I’m genuinely not seeing it.
Again, I don’t see how this follows. Before the split, it is a single entity (and it would develop into a single human person if it did not split). After, it is two.
Your claim is that twinning doesn’t count because it is an abnormality.
Then it was not a single human being before the split.
A mosaic person is one person, not two people, which she would have to be if zygotes are unique human beings at fertilization.
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Why? You are basically just saying “you’re wrong because you’re wrong”. Could you elaborate on your reasoning here?
You seem to be asserting that if there are two human beings after twinning occurs, then there must be two before (and conversely, for mosaics, if there are two before, then there are two after). Or at least, you seem to be asserting that by believing human life starts at conception, I must be committed to this “conservation of persons” principle.
But that is just what I explicitly suggested is not the case when I first joined this thread. If you look at the embryo at some point before the twinning event, it is functioning as a single organism (just as an embryo that doesn’t end up twinning) - is it not? In the twinning event, the matter that makes up the embryo is reorganized and it afterwards functions as two independent organisms. And that effectively happens in reverse for mosaics (though the details of the reorganization are obviously different).
All I’m doing then is identifying human persons = human organisms, a belief which has both philosophical and religious justifications supporting it.
Zygotes are not unique human beings. The wrapper is a better marker for uniqueness than the genetic identity of the stem cells inside, but even the wrapper can split and do just fine.
No, it has the potential to be more than one unique human being.
And what I’m doing is pointing out that human embryos do not equal human persons, so as a rule, unique human lives cannot possibly begin at conception.
That doesn’t contradict what I’m saying, though. Having the potential to split and function as more than one organism does not mean that, prior to any such splitting, it is functioning as more than one organism. Prior to splitting it is functioning as a whole.