The Inductive and Deductive Methods in Customary International Law Analysis: Traditional and Modern Approaches

Abstract

This paper will criticize the current characterization of customary international law analysis as falling into two competing analytical methods, specifically, the “traditional” and “modern” methods. Following Koskennieni, Roberts, Wouters, Ryngaert, and others, contemporary customary international legal analysis is said to have divided into two schools: the traditional and modern. These schools are supposed to reflect the use of the inductive and deductive methods, respectively, and, in turn, to either apologize for the freedom of state action or establish a utopia where the freedom of the state is limited. This image of struggle between competing methods, however, does not fully capture the ways in which the inductive and deductive methods are actually intertwined in customary international law analysis. The methods are not two opposing monolithic techniques. Instead, in practice, the methods are intermixed, combining a variety of choices. Deductive steps are taken regarding the use of induction, inductive steps are taken in reaching patterns from practice, deductive steps are taken in identifying sample pools, and so on. This paper concludes that induction and deduction are both used in parallel in most analyses of customary international law in a delicate, yet valuable, balance of corrective tension. Furthermore, this situation is neither traditional, nor modern – in a chronological sense – but is consistent throughout the history of customary international law analysis. Following an introductory section reviewing the background to the debate over approaches, the paper will consider deduction and induction in more detail, attempting to understand these two methods of logical reasoning. Then the author will examine the way customary international law is analyzed by international tribunals by deconstructing the analytical process into smaller logical steps. For each step, an analysis will be undertaken of whether the conclusion is reached through induction or deduction, and whether this approach is consistent across tribunals and historical eras. Through this approach, the paper will take a first step to suggest the complex ways inductive and deductive analyses are layered in the assessment of customary international law.