The facts of fertilization

In responding to a new argument that the human embryo is not yet a human being, Robert George and Patrick Lee explain the facts:

Fertilization in humans and other mammals produces a new member of the species in the embryonic stage of its natural development. That is to say, the entity produced by the union of spermatozoon and oocyte is a complete, though developmentally immature, organism. Unlike the gametes, it is not merely part of another organism; nor is it merely something that can be used to produce a complete organism. At fertilization, the ovum and the sperm cease to be and something new comes to be — an organism (the embryo) whose genetic constitution and epigenetic state orient and dispose it to develop in the direction of maturity as a member of the species.

As Jay Watts puts it, "An embryo becomes a fetus becomes a newborn becomes a child and eventually becomes an adult who posts blogs and argues that his human brothers and sisters in the earlier stages of our development ought not to be destroyed because their deaths profit the rest of us."