What is the difference between the divine command theory among the Ashʿarites and the natural law theory of Aquinas?

The debate between the divine command theory among the Ashʿarites and the natural law theory of Aquinas represents one of the deepest disagreements in religious moral philosophy. Understanding the difference between them is necessary for comprehending how ethics is grounded in both Islamic and Christian philosophical traditions.

Inadequate Responses to Avoid

From some contemporary Ashʿarites: "Aquinas's theory makes reason sovereign over revelation" is a misleading oversimplification. Aquinas does not make reason independent of God, but rather sees reason as discovering what God has embedded in the natures of things. "Natural law contradicts divine transcendence" confuses transcendence with arbitrary absoluteness.

From some Thomists: "The Ashʿarites make ethics arbitrary and meaningless" is a caricature. The Ashʿarites have precise justifications for their position regarding divine freedom of will and wisdom. "Divine command theory leads to moral nihilism" is an exaggeration that does not consider the Ashʿarite theological context.

Divine Command Theory Among the Ashʿarites

The principle among the Ashʿarites: Good (ḥusn) and evil (qubḥ) are determined by revelation, not by reason. What God commands is good, and what He forbids is evil. There is no inherent moral value in actions apart from divine command and prohibition.

The theological foundation: Absolute freedom of divine will. Nothing is obligatory upon God, and He is not questioned about what He does. If He were to command what we today regard as "evil," it would become good merely by His commanding it. This is not arbitrariness but rather the transcendence of divine will from constraints.

The epistemological dimension: Human reason cannot objectively perceive good and evil independently. What we see as "obviously good" may be merely social custom or psychological inclination. Revelation alone is the source of certain moral knowledge.

Natural Law Theory in Aquinas

The principle in Aquinas: Three interconnected levels of law:
- Eternal Law (Lex Aeterna): The divine wisdom that governs creation
- Natural Law (Lex Naturalis): The rational creature's participation in eternal law
- Human Law (Lex Humana): The application of natural law to particular cases

The metaphysical foundation: Things have natures and ends (teloi). Good is what realizes a thing's end. Reason can perceive these ends and thus know good and evil objectively, but this knowledge remains dependent on God who created these natures.

The epistemological dimension: Reason discovers moral law; it does not invent it. Basic principles (preservation of life, procreation, social life, knowledge of truth) are perceived by natural reason even without special revelation.

Essential Points of Difference

Source of moral obligation. Among the Ashʿarites: Divine will directly. In Aquinas: The nature of things as God created them.

Role of reason. Among the Ashʿarites: Discoverer of divine command only, not establisher of moral judgment. In Aquinas: Perceiver of moral law embedded in natures.

Relationship between revelation and reason. Among the Ashʿarites: Revelation is the sole source of certain moral knowledge. In Aquinas: Revelation completes and confirms what reason perceives, and adds what transcends its capacity.

The Euthyphro dilemma. The Ashʿarites explicitly choose the first horn: good is good because God commanded it. Aquinas attempts a middle position: God commands good because it is consistent with His own good nature.

Strengths and Weaknesses of Each Theory

Ashʿarite divine command theory is strong in: Absolute divine transcendence, conceptual simplicity, avoiding making ethics independent of God. Weak in: Difficulty explaining common moral intuitions, the challenge of the divine arbitrariness problem.

Thomistic natural law theory is strong in: Explaining shared moral intuitions, enabling moral dialogue with non-believers, consistency with moral realism. Weak in: Metaphysical complexity, dependence on Aristotelian concepts that may not be necessary.

Sites of Contemporary Debate

In contemporary Islamic philosophy: Attempts at reconciliation (Taha Abd al-Rahman), revival of the Muʿtazilite position on rational moral evaluation (Muhammad Abid al-Jabiri), renewed defense of the Ashʿarite position (Said Foudah).

In contemporary Christian philosophy: Modified Divine Command Theory in Robert Adams and Philip Quinn, attempts to develop natural law without Aristotelian metaphysics (John Finnis).

Unexpected Convergences

Despite apparent differences, there are important convergences. Both positions affirm that God is the ultimate source of ethics. Both reject absolute moral relativism. Both face challenges from contemporary secular moral philosophy.

In the context of god-database, both positions contribute to rational preference (rajḥān ʿaqlī) for theism: the existence of deep philosophical debate about the foundation of ethics within the theistic framework demonstrates the richness of this framework and its ability to address fundamental questions.

Where We Stand Today on This Debate

The debate has not been settled, but it has evolved. The contemporary challenge is not only choosing between the two theories, but developing a theistic moral theory that incorporates insights from both and transcends their weaknesses, while responding to contemporary challenges from neuroscience, anthropology, and evolutionary moral philosophy.

For Advanced Reading

─ Advanced level: Contemporary divine command theories and Wes Morriston's critique
─ Al-Bāqillānī, al-Tamhīd fī al-Radd ʿalā al-Mulḥida (foundations of Ashʿarite theory)
─ Aquinas, Summa Theologica I-II, qq. 90-97 (foundations of natural law theory)
─ Hourani, Reason and Tradition in Islamic Ethics (Cambridge, 1985)
─ "Divine Command Theory" and "Natural Law Theory" pages on the website