Deeper problems for Noonan's probability argument against abortion: on a charitable reading of Noonan's conception...

In 'An Almost Absolute Value in History' John T. Noonan criticizes several attempts to provide a criterion for when an entity deserves rights. These criteria, he argues are either arbitrary or lead to absurd consequence. Noonan proposes human conception as the criterion of rights, and justifies it by appeal to the sharp shift in probability, at conception, of becoming a being possessed of human reason. Conception, then, is when abortion becomes immoral. The article has an historical and a philosophical goal. The historical goal is to carefully present the probability argument in a charitable manner. The philosophical goal is to offer a unique criticism of Noonan's probability argument against abortion. I argue that, even on a very charitable reading of Noonan's argument for the conception criterion, this criterion is also susceptible to charges of arbitrariness and absurdity. Noonan's claim that probability shifts have anything to do with the moral rights of fetuses cannot be made coherent. I also show that there are problems with Noonan's assumptions about moral rights and the potential to become a being possessed of human reason.