1 Bartosz Brożek Law, Normativity, and Supervenience The main goal of this chapter is to consider what it means that the law supervenes on facts (henceforth: the supervenience thesis). However, before I sketch my answer to this question, I will attempt to uncover the motivation behind the claim that the law is a supervenient entity. I will argue that the search for a more nuanced account of the relationship between legal rules and facts stems from the failure of two quite straightforward ways of conceptualizing it, which I call separation and reduction. Since legal rules can neither be fully separated from facts, nor reduced to them, the way is wide open to consider other accounts of the link between the law and psychological and/or sociological phenomena. It transpires, however – or so I will argue – that the alternative supplied by the supervenience thesis has its own limitations. In particular, while it provides a satisfactory account of the normative character of legal properties, it fails to do the same in the case of legal rules. 1. Separation The first view regarding the relationship between legal rules and facts may be deemed separation: there exists a gap between what is and what ought to be such that there is no identifiable relation between facts and norms. In legal philosophy, the doctrine which explicitly embraces separation seems to be Hans Kelsen’s conception of law. Kelsen's idee fixe is best encapsulated by the title