RT Journal Article SR Electronic T1 Biological processes and moral events. JF Journal of Medical Ethics JO J Med Ethics FD BMJ Publishing Group Ltd and Institute of Medical Ethics SP 144 OP 147 DO 10.1136/jme.14.3.144 VO 14 IS 3 A1 S Buckle YR 1988 UL http://jme.bmj.com/content/14/3/144.abstract AB It is often argued that the continuity of the processes of embryo development precludes the establishment of morally significant boundaries, once development is under way. These arguments typically claim that marking out any moral boundaries requires identifying particular significant events, and that in such circumstances this is either impossible or arbitrary. In this paper it is argued that arguments of this kind are not cogent. The paper concludes by indicating where the real problems lie.