Metaphysical accounts of the zygote as a person and the veto power of facts.

That the soul of a human person is infused at conception is a metaphysical claim. But given its traditional articulation, it has the empirical consequence that the zygote must have a substantial continuity with the adult person, a continuity which is already determined at conception. This empirical consequence is contradicted by the fact that the zygote may become a hydatidiform mole, or several persons. The metaphysical claim is falsified by the facts.