Many people working in bioethics take pride in the subject's embrace of a wide range of disciplines. This invites questions of what in particular is added by each. In this paper, I focus on the role of philosophy within the field: what, if anything, is its unique contribution to bioethics? I sketch out a claim that philosophy is central to bioethics because of its particular analytic abilities, and defend its place within bioethics from a range of sceptical attacks.