 Dworkin’s rich and complex arguments attracted various lines of reply from positivists. One response denies the relevance of the phenomenological claims. Controversy is a matter of degree, and a consensus-defeating amount of it is not proved by the existence of adversarial argument in the high courts, or indeed in any courts. As important is the broad range of settled law that gives rise to few doubts and which guides social life outside the courtroom (see Leiter 2009). As for the diversity argument, so far from being a refutation of positivism, this is an entailment of it. Positivism identifies law, not with all valid reasons for decision, but only with the source-based subset of them. It is no part of the positivist claim that the rule of recognition tells us how to decide cases, or even identifies all relevant reasons for a decision. Positivists accept that moral, political or economic considerations are properly operative in legal decisions, just as linguistic or logical ones are. Modus ponens holds in court as much as outside, but not because it was enacted by the legislature or decided by the judges, and the fact that there is no social rule that validates both modus ponens and also the Municipalities Act is true but irrelevant. The authority of principles of logic (or morality) is not something to be explained by legal philosophy; the authority of acts of Parliament must be; and accounting for the difference is a central task of the philosophy of law.