This book represents an initial attempt to do that which we at least can no longer avoid: to ask about the origin and validity of our moral assumptions, to see the way in which ethics and science have mutually influenced each other, to move away from practical problems of decision making to some of the larger theoretical issues which ultimately come to shape the way decisions are made. That moral philosophy has been in disarray for some decades is a proposition with which few will argue. Nor will many contend that there is any greater clarity at present on the moral assumptions and goals of sicence and medicine. Perhaps it is too much to hope that progress can be made -- perhaps we are, as a society and a culture, going to be forced to live with, and to live out, the present confusion. But both moral philosophy and the sciences do share a common premise, so far unchallenged: that it is always worth the effort to understand more, to attempt to think more deeply, to remain congenitally uneasy in the face of confusion, uncertainty, and unanswered questions. - Preface.