This chapter outlines the ‘four principles’ approach which is prevalent in medical ethics. Principalism was adopted as the ethical method of HUMAINE. This chapter introduces this method and also provides an account of the various criticisms of it. The chapter also includes some discussion of the relationship between ethics and scientific research. The purpose of this discussion is to show how ethics and good ethical research can be embedded in scientific practice. In conclusion, the chapter addresses the importance and the usefulness of considering fears that are embodied in works of science fiction when trying to deal with concerns and fears of the public. Consideration of the ethics of the possible is of massive practical importance and indeed should be a priority for those who are working within research groupings like HUMAINE. It is, however, often important to consider the ethics of what may never be possible – the science fiction if you like. When considering the impossible it will be important to stress the fact that these things are not and may never be possible. The role of this type of consideration lies in the importance of public engagement and showing that possible future scenarios are being taken into account by those who are pushing forward science and technology in this area.