Communis Aestimatio and the Normal Justification Thesis: An Incorporationist Demonstrative Against Raz's Sources Thesis

Abstract

Legal philosopher H.L.A Hart articulates an idea of “inclusive” or “incorporationist” positivism, a theory which admits of the reality and qualified use of moral principles as criteria for legal validity. Joseph Raz’s own exclusive positivism denies the use of moral principles whatsoever on grounds of the sufficient and preemptive quality of law understood as authority. A rejoinder to Raz (and Dworkin), Hart’s posthumous publication of Postscript to the Concept of Law inspired the late 20th-century Coleman-Waluchow movement in defense of inclusive positivism. Beyond a general restatement of ideas as they exist, this essay joins that movement by offering a new intervention against Raz’s normal justification thesis (NJT). It aims to show that a morally preemptive quality does not follow from authority’s ability to help subjects realize dependent reasons better than individual evaluation, and thus undermines the inferential basis for Raz’s sources thesis. In turn, I posit Domingo de Soto’s communis aestimatio as an incorporationist demonstrative to show that the contingent inclusion of moral principles can, in fact, help subjects realize dependent reasons NJT is meant to explain while remaining irreducibly evaluative in nature. To illustrate the substantive use of this theory, the natural law principle of commutative justice in exchange is evidenced as the “dependent reason” and moral basis for equity and prudence doctrines in Anglo-jurisprudence. The essay additionally joins efforts in the scholarly recovery of the School of Salamanca.