In moral philosophy the principle of double effect traditionally refers to conflict situations in which an action or series of actions will result in multiple effects, some good and some bad. It parallels the contemporary policy concept of dual use: the idea that scientific knowledge or technological artifacts can serve multiple purposes, depending on the context. Dual use targeting and dual use research are areas that sometimes raise ethical dilemmas about the production and use of scientific knowledge and technologies but on other occasions provide multiple justifications for a single policy. Double effect seldom is referred to explicitly in those situations, but its general conditions may provide conceptual clarity with regard to moral permissibility. However, at the level of practical political decision making activities such as risk assessment, technology assessment, and scenario building provide better guidance for handling the ethical...