St. Thomas Aquinas: Reason, Faith, and Natural Law

Posted on Aug 8, 2024 in Philosophy and ethics

Reason and Faith

A preliminary question to understanding Thomist thought is the solution given by St. Thomas to the scholastic problem: the compatibility of reason and faith. Reason alone can attain knowledge of the truths of the world (ontology). About God, however, reason can only say “what not” (natural theology). That God is, can only be known by man through reason if it becomes the handmaiden of faith, to clarify their meaning (revealed theology).

Natural Theology

The Summa Theologica begins with questions of natural theology:

  • a) Is it necessary to demonstrate the existence of God? Yes, because we cannot perceive God directly, and because Atheism is an irrational attitude.
  • b) What kind of demonstration would it be? It must be assumed that the world offers to the senses, reflecting the action of a necessary cause (proof a posteriori). It is wrong, therefore, the ontological argument (demonstration a priori).
  • c) What, specifically, are those demonstrations? The five ways.
  • d) How would God show Himself in these demonstrations? As the mover of everything that changes (1st way), the uncaused First Cause from which all things were created (2nd); as a necessary being (3rd), as the Entity with the highest degree of perfection (4th), and as the end toward which everything tends (5th).

Ontology

The world created by God is consistent, in general, with the explanation given by Aristotle:

  • Theory of Hylomorphism: All being is an integration of matter (hyle) and form (morphe).
  • Theory of the Four Causes: Any change or movement in an entity is explained by the action of four causes: material, formal, efficient, and final.
  • Aristotelian Cosmology: The Earth is at the center of the universe.

However, the thought of St. Thomas is not just a repetition of Aristotelianism. In his effort to reconcile Aristotelian philosophy and Christian dogma, he also used brilliant ideas of other major Greek thinkers, Christians, and even Muslims or Jews, such as Plato, Plotinus, St. Augustine, Avicenna, Averroes, Maimonides…

Anthropology

Man is the most perfect contingent being because “he is created in the image and likeness of God.” Man has a body and soul. Being the seat of the soul’s powers, we most resemble God.

This unity must be understood:

  • Not in the Platonic sense: separate substances; the body as a prison of the soul; the immortal soul needing the body at all.
  • But neither strictly Aristotelian: the soul is the form of corporeal matter; as form and matter are not separable, the death of the body appears to represent the death of the soul.

The Thomist solution is to imagine the soul as a quasi-substance: the body can be removed temporarily, but it does not allow the soul to achieve perfection. That is why eternal life is to be assumed, that true happiness involves the resurrection of the flesh.

Ethics

The ultimate aim for humans is happiness. Aristotle believed that happiness was achieved by exercising our intellectual faculties, that is, seeking the knowledge of truth and the golden mean (virtue) between the passions.

But St. Thomas understands that as God is the supreme Truth and the highest good, beyond the limited human intellect (mentioned above concerning the scholastic problem), full happiness cannot be achieved in this world alone.

Only after the resurrection of the body (i.e., the recovery of the ontological plenitude of man), and the eternal contemplation of God, can we attain this happiness to which we aspire.

Life should be focused on obtaining that eternal life which God has promised us if we keep His commandments.

But what commandments are those that we have to comply with? Here, St. Thomas routed the text of Question No. 94:

  • God has established a set of principles that necessarily govern the world: eternal law.
  • Part of that eternal law regards human behavior: the natural law.

The natural law is:

  • Universal (regards all human beings and in all ages)
  • Immutable (never changes)
  • Indelible (is inscribed in the depths of the human heart, although humans may not know it)

The difference between human and other beings is that natural law allows disobedience, unlike the rest of the eternal law. Human beings have the freedom to obey God’s laws or not.

Politics

In politics, St. Thomas also draws on Aristotelian thought, but does not fold. His Christian and his ontological and ethical thinking led him to certain innovations.

  • There are three forms of legitimate government (monarchy, aristocracy, and democracy) and three illegitimate (tyranny, oligarchy, demagogy).
  • The ultimate goal of any form of government should be encouraging the eternal salvation of its subjects.
  • As such, the civil power should be subject—at least in certain cases—to the ecclesiastical power.
  • On the other hand, the autonomy that St. Thomas has established for reason concerning faith gives the president a degree of autonomy, with respect to religious power, that was much greater than was accepted in medieval thought before him.
  • The right of any society must be founded on that part of natural law that regards the coexistence between humans; the part St. Thomas called the natural law.

The Five Ways:

  1. The Argument from Motion: Things move, and something must have initiated that motion. This First Mover is God.
  2. The Argument from Efficient Cause: Everything has a cause, and there must be an Uncaused Cause, which is God.
  3. The Argument from Contingency: Things exist contingently (they could not exist), so there must be a Necessary Being, which is God.
  4. The Argument from Gradation: There are degrees of perfection in things, implying a Perfect Being, which is God.
  5. The Argument from Design: Things act for an end or purpose, even unintelligent things, implying an Intelligent Designer, which is God.