Human beings commonly engage in activities that are rational in the sense that they have aims (goals or ends) that re ect their values and that they attempt to realize by employing means that are believed to realize those aims. e activities of scientists are no exception; they also have aims that re ect what they value. us they might have personal aims they wish to realize through science, such as satisfying their curiosity, obtaining job security and comparatively high level of pay or engaging in an activity that is exciting and challenging. Scientists can also have professional aims such as attracting grants, organizing research teams or editing an in uential journal in their eld. Finally they might have humanitarian goals to realize through science, such as increasing human powers over nature (e.g. the prediction, control or amelioration of oods and earthquakes), increasing powers over ourselves (such as the illnesses to which we are prone, or means of social control, etc.), or making innovations that increase productivity, employment and wealth through a “knowledge economy”. Generally, but not always, scientists who apply science have humanitarian goals in mind. But, as is all too well known, there can be unintended consequences of their choices that can undermine these goals; we mention one of these shortly.