Baby Fae: a beastly business.

The Baby Fae experiment has highlighted the growing trend in medicine of using animal parts in the treatment of humans. This paper raises the question of the logical and moral justification for these current practices and their proposed expansion. We argue that the Cognitive Capacity Principle establishes morally justified necessary and sufficient conditions for the use of non-human animals in medical treatments and research. Some alternative sources for medical uses are explored as well as some possible programmes for their implementation.