In this chapter, I attempt to explain the reasons for applying juristic concepts in legal reasoning. I argue that reasons are facts that count in favour of such application. Usually, the reason for doing something derives from the fact that it is valuable or serves some goals. Therefore, the reasons for applying juristic concepts are closely bound up with the idea of value. I endeavour to determine what of sort of values these are. I distinguish two kinds of values: in a stronger sense and in a weaker sense. The key assumption underlying this distinction is that both kinds of values give rise to the following the rule: “X ought to apply juristic concepts in legal reasoning”. I also distinguish another reason to follow the above rule, namely the fact that others also follow it. To be precise, the reason derives from the fact that a relevant legal community respects a specific conventional social practice, a practice founded on the mutual reciprocal expectations of the members of the community, anticipating that there is a conventional link between a value and a juristic concept. Based on mutual reciprocal expectations, members of the community anticipate that a particular juristic concept realises the important value of legal reasoning in the best way. Finally, if we accept that the reason to do something derives from that fact that doing something is valuable or serves some goals, then we can distinguish three types of arguments for the application of juristic concepts in legal reasoning: axiological, teleological and axiological-teleological arguments.