Thomism is the philosophical school that arose as a legacy of the work and thought of Thomas Aquinas (1225–1274), philosopher, theologian, and Doctor of the Church. In philosophy, Aquinas‘ disputed questions and commentaries on Aristotle are perhaps his most well-known works. In theology, his Summa Theologica is one of the most influential documents in medieval theology and continues to be the central point of reference for the philosophy and theology of the Catholic Church. In the 1914 encyclical Doctoris Angelici Pope Pius X cautioned that the teachings of the Church cannot be understood without the basic philosophical underpinnings of Aquinas’ major theses:
The capital theses in the philosophy of St. Thomas are not to be placed in the category of opinions capable of being debated one way or another, but are to be considered as the foundations upon which the whole science of natural and divine things is based; if such principles are once removed or in any way impaired, it must necessarily follow that students of the sacred sciences will ultimately fail to perceive so much as the meaning of the words in which the dogmas of divine revelation are proposed by the magistracy of the Church.
From which I, REC, emphasize:
Thomas Aquinas holds that the existence of God can be demonstrated by reason, a view that is taught by the Catholic Church. The quinque viae (Latin: five ways) found in the Summa Theologica (I, Q.2, art.3) are five possible ways of demonstrating the existence of God, which today are categorized as:
- 1. Argumentum ex motu, or the argument of the unmoved mover;
- 2. Argumentum ex ratione causae efficientis, or the argument of the first cause;
- 3. Argumentum ex contingentia, or the argument from contingency;
- 4. Argumentum ex gradu, or the argument from degree; and
- 5. Argumentum ex fine, or the teleological argument.
The existence of God and other like truths about God, which can be known by natural reason, are not articles of faith, but are preambles to the articles; for faith presupposes natural knowledge, even as grace presupposes nature, and perfection supposes something that can be perfected. Nevertheless, there is nothing to prevent a man, who cannot grasp a proof, accepting, as a matter of faith, something which in itself is capable of being scientifically known and demonstrated.
Aquinas responds to the problem of evil by saying that God allows evil to exist that good may come of it, (for goodness done out of free will is superior than goodness done from biological imperative) but does not personally cause evil Himself.
View of God
Aquinas articulated and defended, both as a philosopher and a theologian, the orthodox Christian view of God. God is the sole being whose existence is the same as His essence: “what subsists in God is His existence.” (Hence why God names himself “I Am that I Am” in Exodus 3:14.) Consequently, God cannot be a body (that is, He cannot be composed of matter), He cannot have any accidents, and He must be simple (that is, not separated into parts; the Trinity is one substance in three persons). Further, He is goodness itself, perfect, infinite, omnipotent, omniscient, happiness itself, knowledge itself, love itself, omnipresent, immutable, and eternal. Summing up these properties, Aquinas offers the term actus purus (Latin: “pure actuality”).
Aquinas also understands God as the transcendent cause of the universe, the “first cause of all things, exceeding all things caused by him,” the source of all creaturely being and the cause of every other cause. Consequently, God’s causality is not like the causality of any other causes (all other causes are “secondary causes”), because he is the transcendent source of all being, causing and sustaining every other existing thing at every instant. Consequently, God’s causality is never in competition with the causality of creatures; rather, God even causes some things through the causality of creatures.
Aquinas was an advocate of the “analogical way”, which says that because God is infinite, people can only speak of God by analogy, for some of the aspects of the divine nature are hidden (Deus absconditus) and others revealed (Deus revelatus) to finite human minds. Thomist philosophy holds that we can know about God through his creation (general revelation), but only in an analogous manner. For instance, we can speak of God’s goodness only by understanding that goodness as applied to humans is similar to, but not identical with, the goodness of God. Further, he argues that sacred scripture employs figurative language: “Now it is natural to man to attain to intellectual truths through sensible objects, because all our knowledge originates from sense. Hence in Holy Writ, spiritual truths are fittingly taught under the likeness of material things.”
In order to demonstrate God’s creative power, Aquinas says: “If a being participates, to a certain degree, in an ‘accident,’ this accidental property must have been communicated to it by a cause which possesses it essentially. Thus iron becomes incandescent by the action of fire. Now, God is His own power which subsists by itself. The being which subsists by itself is necessarily one.”