Philosophy of Evolution: For Human Body

The Thomistic Foundations


St. Thomas is useful in the question of the possible evolution of human body. 



Does St. Thomas endorse a universal hierarchy in which nature is directed toward life? Yes, St. Thomas has a global view of the world moving toward the same goal.32 St. Thomas maintains: "But since, as was already stated, everything which undergoes motion tends as such toward a divine likeness in order to be perfect in itself, and since a thing is perfect in so far as it becomes actual, it follows that the intention of everything that is in potentiality is to tend to actuality by way of movement. Hence the more final and the more perfect an act is, the more the appetite of matter is inclined to it. Therefore the appetite whereby matter seeks a form must tend toward the last and most perfect act to which matter can attain, as to the ultimate end of generation. Now certain grades are to be found in the acts of forms. For primary matter is in potentiality, first of all, to the elemental form. While under the elemental form, it is in potentiality to the form of a compound; wherefore elements are the matter of a compound. Considered under the form of a compound, it is in potentiality to a vegetative soul; for the act of such a body is a soul. Again the vegetative soul is in potentiality to the sensitive, and the sensitive to the intellective. This is shown in the process of generation, for first in generation is the fetus living a plant life, afterwards the life of an animal, and finally the life of man. After this no later or more noble form is to be found in things that are generated and corrupted. Therefore, the last end of all generation is the human soul. Consequently, the elements are for the sake of compounds, the compounds for the sake of living things, and of these plants are for the sake of animals, and animals for the sake of man. Therefore, man is the end of all generation. (Aquinas Summa Contra Gentiles 3. 22)33

Does St. Thomas teach that lower creatures are in service of higher creatures? Yes, he does, and so reprises Aristotle who taught that "nature proceeds little by little from things lifeless to animal life" and "there is observed in plants a continuous scale of ascent toward the animal."34 This observation of natural ascent is helpful to understand the evolutionary progress toward the human body.35 St. Thomas notes, "...less noble creatures are in the service of the more noble...Further, every creature is in the service of the perfection of the universe...Finally, the totality of the universe with all its parts is ordered to God as its goal" (Aquinas Summa Theologiae 1. 65. 2).36

Does St. Thomas consider the human body as an essential, a fundamental, and a principle of life of the human being? Yes, St. Thomas had a vision of man that is full, complete, and integral: body and soul; and although he valued the spiritual dimension of man, the somatic element was no less important.37 St. Thomas notes that if you could say the soul is man, then you would have to admit that "the sensitive soul completes its operation without the body; because in such a case, all the operations which we attribute to man would be exclusively from the soul; because everything is identified with the subject which causes its own operations. So man will be the being who causes the operation of man. But sensation is not the operation of the soul alone (as already proved). Since sensation is a human operation, and there would be no operation of the soul more proper and specific, it is clear that man is not only a soul, but a composit togetherness, which is the result of the union of body and soul" (Aquinas Summa Theologiae 1. 75. 4).38

Does St. Thomas endorse secondary causes? Yes, he does, and this is the key to the current thesis on evolution. St. Thomas affirms the absolute primacy of God as the principle cause of everything produced by nature, but St. Thomas also affirms there are secondary causes in nature. As proof of secondary causes, St. Thomas has three arguments (Aquinas Summa Theologiae 1. 105. 5).39 First, without secondary causes there would be no connection for creatures between their causation and the effect; creatures would be impotent and their powers in vain. Second, every being exists through its operations, so that without secondary causality, creatures existence would be imperiled. Third, less perfect things are ordered to more perfect: matter is ordered to form as the first act, and matter is ordered to operation as the second act, in such a way that operation is the goal of created things. Therefore, St. Thomas confers upon secondary causes the full share of being and efficacy to which they are due. In the real world, the nature of the effect is similar to the nature of the cause, so that warmth does not chill, and humans generate humans. So the existence of natural laws suppose that God created beings endowed with causality.40

Author:  John Edward Mulvihill, S.T.D., D.Min., Ph.D.
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