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Saint Thomas Aquinas

Aquinas's philosophy
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Aquinas's philosophy
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Saint Thomas Aquinas : Aquinas's philosophy

Saint Thomas Aquinas Aquinas worked to create a philosophical system which integrated Christian doctrine with elements taken from the philosophy of Aristotle. Generally, he augmented the Neo-Platonic view of philosophy which, after Augustine, had become tremendously influential amongst medieval philosophers, with insights drawn from Aristotle. In this he was greatly influenced by his reading of contemporary Arabic philosophers, especially Averroes. Aquinas, is, therefore, generally agreed to have moved the focus of Scholastic philosophy from Plato to Aristotle. The extent to which he was successful in doing this is, of course, still hotly debated.

In his writings Thomas does not, like Duns Scotus, make the reader his associate in the search for truth, but teaches it authoritatively. The consciousness of the insufficiency of his works in view of the revelation which he believed he had received was a cause for dissatisfaction.

The writings of Thomas may be classified as,

(1) exegetical, homiletical, and liturgical;
(2) dogmatic, apologetic, and ethical; and
(3) philosophical.
Category (1) includes: Commentaries on Job (1261-65), Psalms I - li, and Isaiah; Catena aurea (1475)- a running commentary on the four Gospels, constructed on numerous citations from the Church Fathers; Commentaries on Canticles and Jeremiah; reportata, on John, on Matthew, and on the epistles of Paul, including, according to one authority, Hebrews i.-x. Officium de corpora Christi (1264). Numerous other works have been attributed to him.

Category (2): In quatuor sententiarum libros; Quaestiones disputatae; Quaestiones quodlibetales duodecim; Summa catholicae fidei contra gentiles (1261-64);

Summa theologioe. - his magnum opus.
Also: Expositio in librum beati Dionysii de divinis nominibus; Expositiones primoe et secundoe decretalis; In Boethii libros de hebdomadibus; Proeclaroe quoestiones super librum Boethii de trinitate.

Category (3): Thirteen commentaries on Aristotle, and numerous philosophical opuscula of which fourteen are classed as genuine.

Familiarity with Jewish philosophy
Aquinas did not disdain to draw upon Jewish philosophical sources. His main work, "Summa Theologić," shows a profound knowledge not only of the writings of Avicebron (Salomon Ibn Gabirol), whose name he mentions, but of most Jewish philosophical works then existing.

Thomas pronounces himself energetically against the hypothesis of the eternity of the world. But as this theory is attributed to Aristotle, he seeks to demonstrate that the latter did not express himself categorically on this subject. "The argument," said he, "which Aristotle presents to support this thesis is not properly called a demonstration, but is only a reply to the theories of those ancients who supposed that this world had a beginning and who gave only impossible proofs. There are three reasons for believing that Aristotle himself attached only a relative value to this reasoning. . . ." ("Summa Theologić," i. 45, art. 1). In this Thomas copies word for word Maimonides's Guide for the Perplexed, where those reasons are given (I:2,15).

His proofs for the existence of God
Thus he gives five proofs of the existence of God, three of which are taken from Jewish philosophers. The first runs as follows: "It is clear that there are in this world things which are moved. Now, every object which is moved receives that movement from another. If the motor is itself moved, there must be another motor moving it, and after that yet another, and so on. But it is impossible to go on indefinitely, for then there would be no first motor at all, and consequently no movement" ("Contra Gentiles," ii. 33). This proof seems to be taken from Maimonides, whose seventeenth proposition reads: "All that which is moved has necessarily a motor" (Guide of the Perplexed, II:16).

Second proof: "We discern in all sensible things a certain chain of efficient causes. We find, however, nothing which is its own efficient cause, for that cause would then be anterior to itself. On the other side, it is impossible to ascend from cause to cause indefinitely in the series of efficient causes….There must therefore exist one self-sufficient, efficient cause, and that is God" ("Contra Gent." i. 22). This is similar to the argument in Bahya ibn Pakuda's Duties of the Heart (chapter on "Unity," 5) and Maimonides' argument in the Guide, II:16.

The third proof runs: "We find in nature things which may be and may not be, since there are some who are born and others who die; they consequently can exist or not exist. But it is impossible that such things should live for ever, for there is nothing which may be as well as not be at one time. Thus if all beings need not have existed, there must have been a time in which nothing existed. But, in that case, nothing would exist now; for that which does not exist can not receive life but from one who exists; . . . There must therefore be in nature a necessarily existent being." This proof is based on Avicenna's doctrine of a necessary and possible being, and is expounded by Maimonides in the Guide, II:19.

Demonstrating God's creative power
In order to demonstrate God's creative power, Thomas 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" ("Summa Theol." i. 44, art. 1). This idea is also expounded by Bahya ibn Pakuda in his "Duties of the Heart."


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