The Four Causes of “Ius” (Res Iusta) as the Proper Sources of Law

Abstract

This article explores what causes the existence of law. By applying the classical doctrine of the four causes (material, formal, agent, and final) and their subcategories (such as exemplary cause and ultimate end) to the principal concept of ius, the research reveals that traditional “sources of law” closely align with the metaphysical causes of res iusta (the just thing). These causes include the constitution, statute laws, jurisprudence, traditions, and doctrine, along with new sources such as the common good, the ultimate end, the legal facts, and the Supreme Being. This metaphysical approach provides a deeper understanding of why they are considered sources of law, expanding considerably the list of sources. The article demonstrates how the very existence of law relies on the existence and nature of its causes. If the causes change, the law will change immediately.