 Theoretical fruitfulness, however, is conceived differently by philosophers and affective scientists. The former often have as their primary target making sense of the human experience of emotions and sometimes to contribute to other projects in philosophy, such as explaining the origins of rational action or moral judgment, or shedding light on what makes life worth living, or investigating the nature of self-knowledge. Affective scientists, by contrast, are more likely to favor a third-person approach that may be highly revisionary with respect to our first-person self-understanding. And their prescriptive definitions are often designed to promote measurement and experimentation for the purposes of prediction and explanation in a specific scientific discipline. 