In a very influential paper, Abortion, Joel Feinberg offers a series of arguments against four popular proposals for the criterion of moral personhood and defends a fifth proposal. In this paper, I demonstrate that two widely-accepted arguments employed by Feinberg against the modified species criterion and the strict potentiality criterion, respectively, are unsound. Moreover, I argue that there is a general feature of his inquiry into the criteria for moral personhood which undermines his efforts to argue convincingly either in favour of his own candidate or against other candidates.