There is a large amount of scientific work on emotion in psychology, neuroscience, biology, physiology, and psychiatry, which assumes that it is possible to study emotions and other affective states, objectively. Emotion science of this sort is concerned primarily with 'facts' and not 'values', with 'description' not 'prescription'. The assumption behind this vision of emotion science is that it is possible to distinguish factual from evaluative aspects of affectivity and emotion, and study one without the other. But what really is the basis for distinguishing fact and value in emotion and affectivity? And can the distinction withstand careful scientific and philosophical scrutiny? The essays in this collection all suggest that the problems behind this vision of emotion science may be more complex than is commonly supposed.