Biological scientists, like scientists in other disciplines, are uncertain about whether or how to use their knowledge and time to provide society with insight and guidance in handling the effects of inventions and discoveries. This article addresses this issue. It presents a typography of structures in which scientists may contribute to social understanding and decisions. It describes the different ways in which these contributions can be made. Finally it develops the ethical arguments that justify the view that biological scientists have (...) social responsibilities. (shrink)