AQUINAS, Philosophy of Saint Thomas.

St. Thomas Aquinas is both theologian and philosopher, but in his thought the two disciplines are kept distinct even in their closest alliance. Philosophy works to its conclusions by the unaided use of human reason; theology depends upon divine revelation and the teaching authority of the church. As a theologian he can make use of the methods and findings of philosophy, and philosophy is thus ancillary to theology but still distinct from it. The two sciences also differ in certain ways as to their subject matter. Some truths can be known only from revelation and belong solely to theology, for example, the mysteries of the Trinity and the Incarnation. Some truths are proper to philosophy, e.g., the physical constitution of bodies. A third class of truths belongs to both sciences. Thus the existence of God can be known both by revelation and by the light of natural reason. In his theory of knowledge Aquinas is realistic. There are no innate ideas; all our knowledge takes its origin from sense experience. The higher Powers of the mind are then able to act upon the sense data and to form abstract and universal ideas. Aquinas' epistemology is thus in keeping with his psychology. Man is one single complete substance, made up of material body and spiritual soul united together. The soul is the substantial form, the animating and energizing principle; it is the principle of life and therefore of growth, sensation, thought, volition, and all other vital activities. Its highest powers are those of intellect, which has the place of primacy, and of free will.

             Metaphysics, or first philosophy, is the science of being as being, and here again Aquinas is a realist: he is concerned with the existent being of finite things, but most of all with the supreme being in whom essence  and existence are one and the same. He develops and applies Aristotle's basic distinction between the actual or Perfect and the potential, or what is capable of perfection. Infinite beings there is always found a mixture of the potential with the actual. A child, for example, is an actual child  and is complete and perfect as a child, but it has many potentialities that are as yet unfulfilled: it is capable of being perfected in size, strength,  knowledge  and  the like. The only being that is devoid of all mere potencies, and is completely actual, or absolutely perfect, is God, the infinite being, pure actuality Connected with this doctrine of act and potency are those of the four causes, material formal efficient, and  final, and of matter and form in physical  objects, both of which likewise  derive from Aristotle.

              God's existence is not self&-evident but it can be proved by human reason in five ways.  These proofs are (1) from movement or change, the passage from the potential to the actual (2) from cause and effect; (3)  from the contingent and the necessary; (4) from the grades of perfection found in things; and (5) from the order in the universe. Aquinas states  these arguments very succinctly and concludes from them that there must  be a first unmoved mover in whom there is no mere potency or lack, a first cause a self-existent being, a supremely perfect being and an adequate  cause for the order found in the universe. Each of these conclusions is a description of the one supreme and infinite being, God, creator and conserves, first cause and last end of all things. The human mind cannot fully comprehend God's nature, but by means of analogy it can show that He must possess in a supreme degree whatever true perfections are found in creatures Moreover, by "the way of negation" it must exclude  from  the concept of God every attribute that implies defect. Hence it is known that God is omnipotent, omniscient, all&-good, immutable and eternal. Since God is eternal, He could have created the universe from eternity, Although human reason cannot demonstrate that the world  is not eternal, that fact is known from revelation As to whether this is the best of universes Aquinas makes careful distinctions. Relatively, that is, as a means to God's purpose in creation, it is the best universe. In the absolute sense. God could have had a different end in view and therefore could have made a different and better universe. He gives a strong solution to the problem of evil, both physical and moral and shows that  it is not incompatible with God's goodness and power.

 In the Summa Theologica and elsewhere Aquinas develops a complete moral system. He analyzes the nature of the specifically human act, the  act done under the control of reason and will, and takes up the subject  of virtues and vices. The three theological virtues of faith hope, and  charity, and their opposing vices and sins are discussed, as are the Four  cardinal virtues, prudence, justice, fortitude, and temperance and the  contrary vices. Not only are all the basic ethical principles and problems  discussed but he is able to give a concrete solution to particular problems, such as those of mendacity, homicide, theft, and many others. In his treatment of morality Aquinas lays great stress on the concept of law, "a dictate of practical reason, proceeding from the ruler who governs a perfect community," and on the reality of the natural law, which is not different from God's eternal law but a participation in it. Both in his moral treatiscs and in doctrine on the state he advances principles that are essential to just government and that have contributed to the growth of democracy. Thus he argues for participation of all the people in the government, shows the necessity of a wellordered society, emphasizes the advantages of a unified rule, and stresses the evils of tyranny.       Even the physical sciences are not ignored, He suggests that the Ptolemaic astronomic theory may be supplanted, and that the earth's roundness is provable by both physics and mathematics.

              Some of Aquinas' treatises are extended discussions of the matter at hand, whereas in the Sunmia Theologica and certain other works he brings to perfection the tripartite method of the medieval schoolmen Aquinas' method consists of five parts, the first of which is the statement of a problem, as "Whether custom can obtain the force of law." Objections to the author's own position are then given followed by an opinion or doctrine contrary to the objections. In the fourth part, which constitutes the body of each article in the work, Aquinas' own doctrine is stated, and at the end the original objections are answered, In the typical article Aquinas will make use of both deductive and inductive reasoning, appeals to experience and fact, and the authority of Sacred Scripture and previous thinkers. He points out that in theology the argument from authority, that is, Scripture and the pronouncements of the church, is the strongest argument, but in philosophy the appeal to the opinion of other thinkers is the weakest argument. His knowledge of the  literature of philosophy and theology is extraordinary. He makes greatest use of the writings of Aristotle and St. Augustine, but countless other men are quoted: great Greeks and Romans, such as Socrates, PIato, Plotinus, Cicero and Seneca; the Fathers of the Church; Averroës, Avicenna, and other Arabians; Jewish thinkers, like Mainionides and ibn-Gabirol; and earlier medieval teachers. Yet he is always economical and never quotes without need. He is never harsh or captious in criticism but follows the rule that truth is to be respected rather than persons.

Great as Aquinas' analytical powers are, they are surpassed by his powers of synthesis and construction. Making use of the best that had been accomplished by the great patristic and earlier medieval thankers, and of Aristotle's concepts, principles, and iiiethods, and adding everywhere his own great original contributions, he produced new syntheses in both philosophy and theology. He showed that there need not be, and indeed could not be, genuine conflicts between faith and reason but that true theology and sound science aid one another. His work illustrates both faith seeking understanding and faith as a way to understanding. Its spirit likewise illustrates the 'Amo ut intelligam of the mystics. He is always's the intellectualist and the realist. Completeness, clearness, and exactness are his marks as both thinker and writer

St. Thomas success was great in his own time and has been long continued. From the 13th century on he has never lacked followers although his influence waned between the 16th and the 19th centuries. The revival of Thomistic studies has been of the most remarkable intellectual movements since the mid-19th century, and today, the thought of St. Thomas Aquinas is more widely held than ever before.