   As Kelsen saw it, there is simply no alternative. More precisely, any alternative would violate David Hume’s injunction against deriving an “ought” from an “is”. Hume famously argued that any practical argument that concludes with some prescriptive statement, a statement of the kind that one ought to do this or that, would have to contain at least one prescriptive statement in its premises. If all the premises of an argument are descriptive, telling us what this or that is the case, then there is no prescriptive conclusion that can logically follow. Kelsen took this argument very seriously. He observed that the actions and events that constitute, say, the enactment of a law, are all within the sphere of what “is” the case, they are all within the sphere of actions and events that take place in the world. The law, or legal norms, are within the sphere of “ought”, they are norms that purport to guide conduct. Thus, to get an “ought” type of conclusion from a set of “is” premises, one must point to some “ought” premise in the background, an “ought” that confers the normative meaning on the relevant type of “is”. Since the actual, legal, chain of validity comes to an end, we inevitably reach a point where the “ought” has to be presupposed, and this is the presupposition of the basic norm.