Abstract

Recently David S. Oderberg has tried to refute three arguments that have been advanced in favour of the view that a human being does not begin to exist at fertilization. These arguments turn on the absence of differentiation between the embryoblast and trophoblast, the possibility of monozygotic twinning, and the totipotency of the cells during the first days after fertilization. It is here contended that Oderberg fails to rebut these arguments, though it is conceded that the first two arguments are not conclusive. They do, however, make it at least as reasonable to deny this early origination as to affirm it. It should be noticed that this is all that is needed by those who have used these arguments to dispute that something with a special moral status exists right from fertilization. Nonetheless, it will be seen that the third argument could be developed to the point of giving a conclusive reason to believe that a human being does not begin to exist at fertilization.