This essay describes the important contribution made by Norberto Bobbio to sociology of law through his writings about the incentive or promotional function of law. His contribution was based on a wide use of the sociological notion of «function» and on a distinction drawn between functionalism, which he saw as a philosophy of social equilibrium, and functional analysis, seen in turn as a method of investigation that was compatible with a social reality featuring conflicting interests and corresponding power strategies, including strategies such as economic incentives. Tools of this kind, which were typical of «noble» welfare policies, have now undergone a degenerative process that may be exemplified in Italy by the ever-increasing use of «discounts» for criminal offences at «attractive » prices.