Some important ideas in Kelsen's Pure Theory of Law can be traced back to Kantian tradition, which has been very influential in Kelsen's thought, particularly in his early period. Among them we find the distinction between two radically different worlds (the world of facts and the world of norms), the normativity of legal science and the idea of validity as a binding force, based on the famous doctrine of the basic norm. These tenets and, especially, the use of a normative (...) concept of validity prove to be incompatible with Kelsen's positivistic programme of a value‐free legal science. The science of law cannot state that legal norms are obligatory or binding without trespassing the limits of Kelsen's ideal of a legal science; on the other hand, it is possible to define the concept of a legal system without resorting to the basic norm. So, if Kelsen is to be regarded as a consequent positivist, the Kantian ingredients of his theory must be rejected and the descriptive concept of validity as membership must be substituted for the normative notion of validity as a binding force. (shrink)