Abstract

Don Marquis offered the most famous philosophical argument against abortion. His argument contained a novel defence of the idea that foetuses have the same moral status as ordinary adults. The first half of this paper contends that even if Marquis has shown that foetuses have this status, he has not proven that abortion is therefore wrong. Instead his argument falls victim to problems similar to those raised by Judith Thomson, problems that have plagued most anti-abortion arguments since. Once Marquis's anti-abortion argument is shown to fail, this raises the question of whether there is some way to circumvent the problems. The second half of the paper argues that this issue hinges on important questions about responsibility for risky behaviour and the duties of parenthood. Because we have yet to develop appropriate theoretical frameworks for judging such questions, we cannot yet know whether Marquis's anti-abortion argument — and indeed most other anti-abortion arguments — can be completed.