Christian fundamentalists argue against abortion on the grounds that fetuses have souls. The argument starts with two premises: that people have souls while animals do not, and that the right to life goes with possession of a soul.
It proceeds by asserting that the developing fetus must acquire its soul at some instant; and because no point after conception is special enough to be that instant, it must happen at conception. (It takes hours for an egg and a sperm to unite, but they could choose some brief part of the process as the crucial "instant".) Therefore, the argument concludes, the fetus has a soul and the same rights as a grown human.
The fetus at any given time either has a soul or it doesn't. There is no intermediate state, no way to change gradually from soul-absent to soul-present, so the change must be instantaneous.
It is normal in quantum mechanics for an object to change gradually from state A to state B, even though there are no intermediate states between A and B.
Take for example, an electron's spin can either point up or down (along whichever axis you choose for the measurement); there is no possible intermediate value it can have. Yet in the proper conditions can reliably and gradually convert spin-down electrons into the spin-up state, over a predictable length of time. What changes is the probability you will find State A vs State B moves gradually from 0% to 100%.
So my question is, When does the Fetus Acquire the soul and is it an instantaneous event or a continuous event. Can someone explain this?