Legal Reasoning and the Construction of Law

There are two competing views on what makes propositions of law true. The one, legal realism, takes it that propositions of law are true because they reflect an independently existing reality of legal facts. These facts would be generated by legal rules which would operate autonomously, without need for human intervention. The institutional theory of law illustrates this view. On this view it is the function of legal arguments to reconstruct the results of the autonomous rule application. The other view is legal constructivism, according to which propositions of law are true because they are the conclusion of the best (possible) legal argument. On this view the function of legal argumentation is constitutive: argumentation determines the contents of the law. This paper argues that legal realism is not very plausible because it is based on metaphysical assumptions which cannot be verified or falsified. Legal constructivism would be more plausible, in particular in the variant where the law is determined by the best actual legal argument. This position is defended by means of a brief exposition of the so-called ‘Erlanger-approach’ to legal