 This is because if efficiency is the normative polestar for both tort and criminal law, then there is a basis for denying the relevance of the metaphysics of causation to the interpretation of legal usages of “cause” that does not depend on any skepticism about that metaphysics. Such a basis begins with the quite correct insight that legal texts are to be interpreted in light of the purposes (values, functions, “spirit, “mischief”, etc.) such texts serve. Often such purposes will justify an interpreter in holding the legal meaning of a term to be quite different from its ordinary meaning in non-legal English. Whether this is so in the case of the legal uses of “cause” depends on what one takes to be the purpose of those legal texts that use “cause”. Consider American tort law.. Following the welfare economics of A. C. Pigou (1920), it was for a time fashionable to think that the purpose of liability rules in tort law was to force each enterprise or activity within an economy to pay its “true costs”. Those costs included damage caused to others by the activity as much as they included traditional cost items of production like labor, raw materials, and capital. The thought was that only if each enterprise paid its true costs would the goods or services produced by that enterprise be correctly priced, and only if such correct pricing occurred would markets achieve an efficient allocation of resources. This came to be known as “enterprise liability” in the tort law theory of 1950s America (Calabresi 1961).