Jurisprudence: Natural Law (Aquinas)

The Natural Law tradition is the oldest school of legal philosophy, dating back to ancient Greece and Rome. Its most systematic proponent was the 13th-century theologian Thomas Aquinas. In his Summa Theologica, Aquinas argued that law is "an ordinance of reason for the common good, made by him who has care of the community, and promulgated." This article provides a comprehensive deep dive into the four levels of law and the famous (and often misunderstood) maxim *Lex iniusta non est lex*.

1. The Hierarchy of Laws

Aquinas identified four types of law:

• Eternal Law: God's plan for the entire universe.
• Divine Law: Law revealed through scripture (e.g., the Ten Commandments).
• Natural Law: That part of the Eternal Law which humans can discover through reason (e.g., the duty to preserve life and seek truth).
• Human Law: Man-made laws (statutes and cases) derived from Natural Law.

2. Lex Iniusta Non Est Lex

Aquinas famously stated that a human law that conflicts with Natural Law is a "perversion of law." It is "not a law, but a perversion of law" (*lex iniusta non est lex*). However, he added a pragmatic caveat: one should still obey an unjust law if it is necessary to avoid "scandal or disturbance"—meaning the collapse of social order.

3. Modern Natural Law: John Finnis

In the 20th century, John Finnis revived Natural Law in Natural Law and Natural Rights. Finnis moved away from theology toward "Basic Human Goods" (Life, Knowledge, Play, Aesthetic Experience, Sociability, Practical Reasonableness, and Religion). He argued that law’s purpose is to coordinate society to allow individuals to flourish in these goods.

4. Critical Analysis & Academic Debate

Legal Positivists like John Austin dismissed Natural Law as "nonsense upon stilts." They argued that "the existence of law is one thing; its merit or demerit is another." However, the Nuremberg Trials—where Nazi officials were prosecuted for "crimes against humanity" despite following German law—provided a powerful historical justification for Natural Law principles.

Conclusion

Natural Law reminds us that the law is not just about power, but about justice. It provides a moral yardstick by which all man-made laws must ultimately be measured.