Adventures in Philosophy: St Thomas Aquinas

Adventures in Philosophy

St. Thomas Aquinas (1225 – 1274)

St. Thomas Aquinas (1225 – 1274)

Philosophy and Theology

Thomas Aquinas (picture) does not accept the Averroist principle of the double truth. Philosophy and theology are distinct but not opposed, and what reason shows to be true is absolutely true in theology also. Moreover, Aquinas does not accept Augustinian illumination, the belief that the eternal truths are imparted to our soul by the Word of God. For Aquinas the intellect is able to reach concepts through abstraction. The proper object of the human intellect is this visible world; our intellect cannot penetrate the mysteries of faith. Nevertheless, the most important religious truths, such as the existence of God and the immortality of the soul, are both the object of reason and the object of faith.

Theory of Knowledge

Knowledge is obtained through two stages of operations, sensitive and intellective, which are intimately related to one another. The object of sensitive knowledge is the particular thing, while the object of the intellect is the “intelligible,” which is arrived at from the particular by abstraction. The intellect has three operations: abstraction, judgment and reasoning.


General Metaphysics: Aquinas accepts the general principles of Aristotle’s metaphysics, in which being is a created composite of potency and act. The general principle of potency and act, applied to those beings in which it is already existent, is specified in a second principle, the principle of matter and form. The principle of individuation is “matter signed by quantity.”

Theodicy: Aquinas does not admit supernatural Augustinian illumination, and hence refuses to accept any proof a priori of the existence of God (argument of St. Anselm). The arguments for the existence of God must be a posterior, and they are solidly certain. Aquinas has presented five different ways in which the intellect can prove the existence of God; each of them consists in a fact of experience, which can be justified only by the existence of the transcendent Being (God). Thus:

The fact of motion induces the mind to affirm the existence of the immovable Mover;
The fact of the production of a new reality demands the existence of the uncaused reality;
The fact of a contingent being implies the existence of a necessary Being;
The fact of the existence in things, to a greater or lesser degree, of the good, the true, and the noble, implies the existence of “absolute perfection”;
The Fact of the order of the whole universe implies the necessity of an Intelligence which is the cause of this order.
Cosmology: In cosmology, Aquinas departs from the dualism of Aristotle; matter is created by God. The whole universe was created by an act of the free will of God, and what happens in the universe finds its counterpart in the wisdom of God.

The Soul: When the form in matter is the origin of immanent actions, it is called soul. Hence there is a vegetative soul, a sensitive soul, and an intellective soul. The human soul is directly created by God, and it is the true form of the body; it therefore performs both organic and inorganic activities. The intellect is an inorganic power of the individual soul. The agent intellect is not one and the same for all but is the human soul itself in so far as the soul is intellectual in nature. As such it is able to abstract the intelligibles from material conditions. Since the human soul is able to perform inorganic operations, it is immaterial, spiritual and immortal.

Ethics and Politics

In opposition to the voluntarism of St. Augustine, Aquinas upholds the primacy of the intellect over the will. Aquinas extends this law even to God; the foundation of creation is the Divine Essence, which is rational; the present order of creation has been willed by God because it was rational. All created beings must follow the natural law, and for rational beings, including man, it is the law of reason. Man is free, and he can abuse his freedom; but every abuse of freedom is an irrational act.

Aquinas departs from Augustinianism also in his doctrine on the state; society is natural to man, and not a consequence of the original fall, as the Augustinians believed. The first step to society is the family and the end of society is the common material good of men. Civil society, therefore, must recognize another superior society, that is, the Church, to which has been entrusted the spiritual good citizens.

The late Dr. Jonathan Dolhenty was the Founder and President of The Center for Applied Philosophy and the Radical Academy, and is Honorary Philosophy Editor at The Moral Liberal. The Moral Liberal has adopted these projects beginning with a republishing and preserving of all of Dr. Dolhenty’s work.