 Posner [1973] made two claims that have usually defined the debate around the philosophical foundations of economic analysis of law. The first claim, often called the positive claim, asserts that common law legal rules are, in fact, efficient. The second claim, often called the normative claim, asserts that common law legal rules ought to be efficient. In both claims, Posner understood “efficiency” to mean the maximization of the social willingness-to-pay but subsequent authors have sometimes used the term in its more conventional economic sense of Pareto efficiency. As both of these claims predate the emergence of behavioral economic analysis of law, each relies on the classical theory.