Modern legal systems are characterized by a tension between two commonplaces: the Rule of Law on the one hand, and the arguable character of law on the other. The Rule of Law calls for legal certainty, predictability and reasonableness; the argumentative character of law implies room for rational disagreement. In this book, expert scholars come together to offer interdisciplinary approaches to debate this tension and its possible reconciliation. Central in their perspective is that reconciliation is possible when the Rule of Law also incorporates rules for reason-giving. Reason-giving should be part of a substantive conception of the Rule of Law. Requiring that legal decision-makers give reasons furthers reasonable outcomes. The analysis of the ideal of rational argumentation and the ideal of the Rule of Law show how insights of two traditions are connected.This collection of essays includes contributions from law, argumentation theory, logic and philosophical perspectives. This multifaceted approach demonstrates the variety of questions that emerge at the intersection of both commonplaces. This volume fills a remarkable void in the current literature on the Rule of Law.