The Union of Soul and Body in Man

a) Nature of the Union — b) Results of the Union — c) Place of the Soul

a) Nature of the Union

A union is either the process of conjoining two or more things into a single reality, or it is the product of such a process. We use the term union to indicate the process of uniting when we say, “The union of the colonies was effected by clear-sighted and heroic statesmen.” We employ the term in its other sense as the product or result of uniting when we cry with Webster, “Liberty and Union, now and forever, one and inseparable,” or when we sing, “The Union forever!”

There are two main types of union, to wit, accidental union and substantial union. Accidental union is manifested in the conjoining of realities in such wise that each keeps its own complete nature and operations, and so the elements (i.e., things united) do not fuse together, so to speak, to constitute a new essence. Such a union is observed in a heap of stones, for example, or in a team of horses hitched together to make the one pulling-force which draws the wagon, or in a mixture of water and sand. Such a union also obtains in the mere contact of one thing with another, as when a workman puts his hand to a tool; tool and workman are in contact and in a real union of a sort, but no new essence or nature is constituted by this union.

Substantial union is the coming-together of two or more incomplete substances into one complete substance of a determinate essence and nature. Prime matter and substantial form are two incomplete substances which, in their substantial union, constitute a complete bodily substance of a definite essential kind. Now, the substantial union of soul and body in man is of this second type. The soul and body of man each constitute an incomplete substance; neither is a complete substance alone (although the soul is complete in the order of substantiality); and in their substantial union they constitute the single complete human substance with its one essence, one nature, and one set of vital operations.

We shall presently see that man has only one soul (for all he has three grades of life) and this one soul is the spiritual or rational soul. Man, therefore, is rightly defined as a rational animal. For man is an animal organism, and man has reason or is rational. This definition of man as a rational animal is called a metaphysical definition. For a definition expresses an essence; it names the elements or parts of that essence; and the parts here named are not natural or physical parts which can actually be separated one from another; the “parts” here mentioned (i.e., “rationality” and “animality”) are realities which the mind understands to be present, but which do not suffer physical partition; the parts here named are metaphysical. If you wish to mention the physical and separable parts of a man, and to express or explain his essence thereby, you have a physical definition of man. Thus, the familiar definition given in the little catechism is the physical definition of man, viz., “man is a creature composed of body and soul. …“

b) Results of the Union

The results of the union of soul and body in man are manifold. Here we are to consider three important ones: (1) A man is constituted by this union as a single essence and nature with the operations of three kinds of living beings. In other words, a man, although he has vegetal, sentient, and rational operations, has only one soul. (2) Each man has his own proper soul; the soul is individuated. The souls of different men are distinct realities; a man is not a part of a world-soul or universal soul-substance, any more than the body of a man is a part of a material world-stuff or world-substance. (3) Man is a rational animal; he is one substance with one essence and nature; and the soul which is the substantial form of the human composite is the rational or spiritual soul.

These three results touch upon and dispose of some erroneous views concerning the body-soul relation in man. There are those who have taught that the body and soul of a man are joined in merely accidental union. Plato seems to have inclined to this view, conceiving the soul as dwelling in the body as a prisoner dwells in a cell — that is, as a separate and complete substance incidentally confined in the body. Descartes, some twenty centuries later, held much the same view. According to this doctrine, man is really two complete substances: the extended or material substance (the body) and the thinking substance (the soul). Such a doctrine makes the substantial union of body and soul impossible to understand; it destroys the unity of human nature. The true doctrine is that body and soul together constitute one substance.

Other errors concern the manner of soul-body interaction. Occasionalism (chiefly that of Malebranche, 1638–1715) held that on the occasion of a movement in the body God produces the corresponding state in the soul, and vice versa. But this is merely a transference of the difficulty, not a solution of it. Pre-established harmony (Leibniz, 1646–1716) held that God at the beginning so arranged the natures of body and soul that they proceed in parallel, like two perfectly synchronized clocks, without ever actually interacting. But this denies the evident fact of body-soul interaction and makes man not one substance but two.

Pan-psychism or psycho-physical parallelism holds that soul and body are manifestations of a universal will-force or world-soul; in special application to man, this doctrine indicates that the universal soul and man’s bodily nature are kept in parallel and harmonious activity. This strange doctrine involves the self-contradictory hypothesis of pantheism, destroys all human individuality, denies the substantial union of body and soul, and contradicts reason and factual experience. Behaviourism (fathered chiefly by John B. Watson, 1878–1958, and associated with the American psychological school of the early twentieth century) denies the existence of soul or mind altogether, and proposes to study only observable bodily behavior. But the very act of denying mind is itself a mental act; behaviourism is self-refuting.

c) Place of the Soul

There are three senses in which a thing may be said to be in a place or located: (i) circumscriptively, when a body occupies a place in such wise that it is bounded by the place and the place is bounded by it; (ii) definitively, when a thing is in a place without being bounded by, or bounding, that place; (iii) informatively or operatively, when a thing is in a place by reason of the fact that it gives actuality to what is in that place and exercises its power through what is in that place.

The soul is in the body informatively or operatively. The soul is, indeed, present in its essence in each and every part of the living body. But the operations of the organism (which is material, and composed of parts) are diversified, and the vegetal and sentient operations require their several distinct organs. One does not hear with the toes or see with the ears or taste with the eyes or digest food with the nose. The one soul is the root-principle of all vital activities, but it exercises its power through different and differently located parts of the organism.

We may say, indeed, in a sort of poetical way, that the soul is chiefly in the head and the heart. But this statement is not literally true. It is justified only in view of the fact that the chief organ of sentient life is the brain, and the chief organ of vegetal life is the heart.

1. The soul does not exercise its proper operations in each and every part of the body. The soul is present in the whole body and in every member, and it gives actuality (i.e., actual existence and vital character) to the whole body and every member. But it exercises its distinct and specific operations through distinct and specifically suited organs. As a result, the loss of a member or organ does not destroy the soul or life of the organism (provided the loss is not fatal to the organic whole), but it does eliminate the operations proper to that member or organ.

2. The mutual influence of soul and body is a fact. Soul affects body and body affects soul. Bodily states influence the soul’s operations, and the soul’s operations have corresponding bodily effects. The man who is tired in body finds his mental work difficult. The man who is anxious or fearful shows it in pallor or in trembling. Grief manifests itself in tears. Fear manifests itself in the “goose-flesh” of the skin. Joy illuminates the face and quickens the step. This mutual influence is the natural consequence of the substantial union of soul and body.

3. The soul does not exercise all the operations of which it is the root-principle in each and every member of the body. The soul is, indeed, present in its essence in each and every part of the living body. But the operations of the organism (which is material, and composed of parts) are diversified, and the vegetal and sentient operations require their several distinct organs. One does not hear with the toes or see with the ears or taste with the eyes or digest food with the nose. The one soul is the root-principle of all vital activities, but it exercises its power through different and differently located parts of the organism. We may say, indeed, in a sort of poetical way, that the soul is chiefly in the head and the heart. But this statement is not literally true. It is justified only in view of the fact that the chief organ of sentient life is the brain, and the chief organ of vegetal life is the heart.

Summary of the Article

In this Article we have learned the meaning of union, and have defined substantial union and accidental union. We have seen that substantial union is the specifically human union — the union of soul and body in man. We have considered the results of this union: man’s single essence and nature embracing three grades of vital operation; the individuality of the human soul; and the metaphysical definition of man as a rational animal. We have examined and rejected several erroneous theories of the body-soul relation: Platonic-Cartesian dualism, occasionalism, pre-established harmony, pan-psychism, and behaviourism. We have explained the sense in which the soul is in the body — informatively or operatively — and have clarified three important corollaries of this doctrine.