Legal rules and legal reasoning: On the nature of legal validity

In this dissertation, I propose a solution to Ronald Dworkin's challenge from hard cases. Hard cases are cases in which the judges agree on the facts of the case and on what the posited law requires, but they disagree on what the law on the matter is. It is commonly thought that hard cases are decided on moral grounds, and that this problem raises the problem of explaining how the law can include unposited moral considerations. Dworkin argues that this problem generalizes, and that a theory of law must explain how all attempts to determine what the law is must make appeal to moral considerations.;Instead, I propose an alternative positivist solution to Dworkin's challenge. First, legal positivists need not accept Dworkin's understanding of source-based considerations as excluding all appeals to morality in their applications By reconfiguring this problematic distinction, positivists can explain who the law can require frequent appeal to morality in the application of its rules. Secondly, I argue, the problem of hard cases is best understood as in instance of the prior problem of distinguishing legal rules from all other rules to which people are subject. And, I hold that Hart's solution to this prior problem solves this problem as well. I thus conclude that the problem of hard cases poses no special threat to legal positivism.;I argue that existing attempts to solve this problem fail. On the one hand, Dworkin argues that every attempt to determine what the law is must include an appeal to all moral considerations. This overstates the role of morality in law. Legal positivists, on the other hand, hold that moral considerations can be legally binding only when they are anticipated by the posited law. This understates the role of morality in law. By making the validity of moral considerations depend on the posited rules, inclusive positivists remain vulnerable to the possibility that a new hard case will arise that is not anticipated by the posited rules, but that the law can resolve nonetheless. And by excluding all moral considerations from law, exclusive positivists fail to explain law as we know it.