Yes, I'm fully aware of the silliness of the argument about unfertilized eggs. This is an example (and an often instructive one) of what is called reductio ad absurdum:   this involves pushing an argument beyond reason to illustrate a point. The point being the word "potential." In essence, both the fertilized and unfertilized egg represent a potential human being. Where do we cease to be concerned about the fate of potential unrealized? That is, where are you going to draw the line?

And indeed I can see the wisdom of pursuing the moral and ethical questions. But how long are we going to do nothing but debate abstract issues? If we continue to debate the matter for the next twenty years, then how many people are going to die needlessly or suffered unnecessarily while we are doing our sums?

What's the moral/ethical answer to that question?

Don Firth