When you really dig into it, nobody actually believes this. If there was a burning building with a cooler of 10 embryos and 1 baby, and they could only save on

When you really dig into it, nobody actually believes this. If there was a burning building with a cooler of 10 embryos and 1 baby, and they could only save one, every single one would grab the baby. But it's the only clean line they can draw about when human life becomes human life, so they nominally stick to it even though they don't hold by any of the logical consequences of doing so.