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 i