Among physicians the most frequently heard argument against physician-assisted suicide is one about the nature of the medical profession. It is argued that the norms of medicine prohibit a physician from ever acting with the intent to kill a patient or to aid him in killing himself. For this reason it is essential, they believe, to maintain a sharp distinction between allowing patients to die, say by the refusal to initiate cardiopulmonary resuscitation (CPR), and acts of assisted suicide.

Certainly the most important and influential article defending this view is one by Leon Kass. It is almost impossible to find an article opposing medically assisted dying in any of the major medical journals, such as the New England Journal of Medicine and the Journal of the American Medical Association, that does not cite this article as establishing the view that physicians must not aid patients in dying. We propose, therefore, to critically examine Kass's arguments.

Kass begins by considering “the question about physicians killing (as) a special case of – but not thereby identical to – this general question: May or ought one kill people who ask to be killed.” Note the phrase “may or ought,” which will assume some importance as Kass develops his argument.