The Egg and I: Conception, Identity, and Abortion.

The article cites the author's argument that he originated not at the moment of his biological conception, but either before or after his biological conception. He also argues that if any familiar "pro-life" moral principle raises moral qualms about the permissibility of zygotic abortion, these qualms apply equally to the permissibility of contraception and abstinence. He also thinks that his primary, metaphysical argument is strong, a related but weaker argument which will serve for most of his moral purposes.