Tom Beauchamp and James Childress have always maintained that their four 
principles approach (otherwise known as principlism) is a globally applicable 
framework for biomedical ethics. This claim is grounded in their belief that the 
principles of respect for autonomy, non-maleficence, beneficence and justice 
form part of a 'common morality', or collection of very general norms to which 
everyone who is committed to morality subscribes. The difficulty, however, has 
always been how to demonstrate, at least in the absence of a full-blooded 
analysis of the concept of morality, whether the four principles are 
foundational, and so globally applicable, in this way. In the recently published 
sixth edition of Principles of Biomedical Ethics, an imaginative and 
non-question-begging empirical method of determining the common morality's norms 
is suggested. In this paper, I outline this method, before arguing that it is 
difficult to see how it might be thought to achieve its purpose.