Gerwirth's ethical rationalism and abortion: a response

In the preface to his seminal work, Reason and Morality (1978), Alan Gerwith writes: "The most important and difficult problem of philosophical ethics is whether a substantial moral principle can be rationally justified." After summarizing his methodology, I demonstrate that (1) Gerwith's attempt to quantify personhood is unrealistic; (2) that his position on abortion rests on the unintelligible notion of "comparable conflict" between mother and unborn; and (3) that he implicitly assumes that personhood is naturally, and not functionally, defined--thereby contradicting himself. Ultimately, I outline an alternative view of personhood, one which avoids the criticism to which Gerwith's theory is particularly susceptible--namely, that personhood is a natural component of human beings from the start, rather than a gradually acquired trait.