The paper focuses on the motives that are given by sociological interpreters to the adoption of norms and values by actors. Most current sociological analysis departs from an application of strict theoretical models such as functionalism or the rational choice model. Instead, it relies on various motives that are not linked together by one general scheme of action. The paper nevertheless tries to investigate the types of reasons that are commonly assessed to the actors. But since many opposite motives can be coherent with the data, it suggests ways of theorizing them that would allow to avoid ad hoc explanations.