Soul is a term rarely used with precise definition in philosophy, religion, or common life. It is generally regarded as descriptive of an entity related to but distinguishable from the body--the spiritual part of human beings that animates their physical existence and survives death.
Primitive religions tend to associate the soul with the vital force in humans and often identify it with particular parts or functions of the body (the heart or kidneys, the breath or pulse). Other religions show traces of such animistic ideas. In Hinduism, the Atman (originally meaning "breath") is the individual factor that is indestructible and that after death is reborn in another existence. But Atman is identified with Brahman, the Source of all things to which the soul ultimately returns when it ceases to have a separate existence. (Buddhism, on the other hand, repudiates the notion of Atman, positing the theory of Anatta, nonself.) Early Jewish thought did not conceive the soul as existing apart from the body except in the shadowy realm of departed spirits (Sheol). Greek and especially Platonic thought divided humans into two parts: body and soul. The soul, often referred to as the psyche, was considered both preexistent and immortal.
The early Christian church lived under the influence of Greek ideas about the body and soul, although biblical teachings about Resurrection were superimposed on them. Throughout the history of the Christian church, there has been no clearly defined and universally accepted metaphysical conception of the soul. Nevertheless, Christian theology and worship have adhered firmly to the conviction of personal survival after death rooted in belief in the love of God and the resurrection of Jesus Christ from the dead.
Philosophy has long been preoccupied with speculation about the existence and nature of the soul and its relationship to the body. In the 20th century many philosophers have argued, following William James, that the concept of the soul is neither verifiable nor necessary to an understanding of humankind's mode of existence in the world.
Charles W. Ranson
Cullmann, Oscar, Immortality of the Soul or Resurrection of the Dead? (1958); Kenny, Anthony J. P., The Anatomy of the Soul: Historical Essays in the Philosophy of Mind (1973); Laird, John, The Idea of Soul (1970); Rank, Otto, Psychology and the Soul (1961); Swinburne, Richard, The Evolution of the Soul (1986).
A Soul is a living being, life principle, person, or individual spiritual nature. It may be ascribed to animals (Gen. 1:30; Rev. 8:9) and to God (Lev. 26:11; Isa. 42:1). It is often used interchangeably with spirit, although distinctions that begin to appear in the OT are carried forward in the NT. Thus while soul in the NT normally means an individual spiritual entity with a material body so that a person is thought of as a body-soul, spirit is the special gift of God which places one in relationship to him. Scripture states that Jesus gave his spirit to his Father (Luke 23:46; John 19:30), but elsewhere it is said that he gave his soul as a ransom for many (Matt. 20:28; John 10:15). In general terms then it can be said that soul in Scripture is conceived to be an immaterial principle created by God, which is usually united to a body and gives it life; however, the soul continues to exist after death in human beings (Matt. 10:28; James 5:20; Rev. 6:9; 20:4), a condition which is ended at the close of this age (I Cor. 15:35-55).
The Early Church
Speculation about the soul in the subapostolic church was heavily influenced by Greek philosophy. This is seen in Origen's acceptance of Plato's doctrine of the preexistence of the soul as pure mind (nous) originally, which, by reason of its fall from God, cooled down to soul (psyche) when it lost its participation in the divine fire by looking earthward. It is also seen in Tertullian's repudiation of Greek ideas and his insistence on the biblical teaching of the union of the soul, an immaterial creation of God, with the material body which has been made for it.
Augustine's great influence was felt in the church in his teaching about the soul as in other matters. Condemning the heathen notions that the soul was originally a part of God, an idea which he calls blasphemy, that it is corporeal, or that it becomes polluted through the body, he saw the soul as a rational-spiritual substance made "like God," and made by him, sustaining and directing the body (The Greatness of the Soul, XIII, 22). Concerning its origin and whether it was created by God or transmitted by parents, Augustine might be unsure (On the Soul and Its Origin, I, 27), but of its "proper abode" and "homeland" he was certain, and that is God (The Greatness of the Soul, I, 2).
Origin of the Soul
Augustine's reluctance to take sides in the debate on the origin of the soul was not shared by his contemporaries. Some Greek church fathers shared Origen's theory that the soul preexisted with God and that it was assigned to a body as a penalty for its sin of looking downward. Most, however, accepted the creationist view that God created each individual soul at the moment that he gave it a body, while some, like Tertullian, held the traducianist theory that each soul is derived, along with the body, from the parents.
Arguments cited in favor of creationism were (1) that Scripture distinguishes the origin of man's soul and body (Eccl. 12:7; Isa. 42:5; Zech. 12:1; Heb. 12:9); (2) that creationism preserves the idea of the soul as a simple, indivisible substance better than traducianism, which requires the idea of the division of the soul and its derivation from the parents; and (3) that it makes more credible Christ's retention of a pure soul than does traducianism.
In behalf of traducianism it was said (1) that certain Scripture supports it (Gen. 2:2; Heb. 7:10; cf. I Cor. 11:8); (2) that it offers the best theory for the whole race having sinned in Adam; (3) that it is supported by the analogy of lower life in which numerical increase is obtained by derivation; (4) that it teaches that parents beget the whole child, body and soul, and not just the body; and (5) that it was necessary for Christ to have received his soul from the soul of Mary in order to redeem the human soul.
Augustine carefully weighed the arguments on each side of the controversy, leaning toward traducianism for a time even while he saw the difficulty of retaining the soul's integrity with this hypothesis; later he admitted that he was perplexed and baffled by the question.
A contemporary theologian who takes essentially the same stance is G. C. Berkouwer, who calls the controversy "unfruitful," inasmuch as it wrongly assumes that the issue is one of horizontal or vertical relations. "Such a way of putting it is far too feeble an attempt to render adequately the greatness of the work of God" (Man: The Image of God, 292). The God of Israel does not create only in the distant past, but he is constantly active in human history, the Creator in horizontal relationships as well as others. To speak about a separate origin of the soul he sees as impossible biblically, inasmuch as this creationist theory sees the relationship to God as "something added to the 'essentially human,' which later is defined independently as 'soul' and 'body.' Both soul and body can then be viewed in different 'causal' relationships without reference to some intrinsic non-causal relationship to God. If, however, it is impossible to speak of the essence of man except in this latter religious relationship, then it also becomes impossible to introduce duality into the origin of soul and of body within the unitary human individual" (303).
M E Osterhaven
(Elwell Evangelical Dictionary)
G. C. Berkouwer, Man: The Image of God; A. Dihle et al., TDNT, IX, 608-66; C. A. Beckwith, SHERK, XI, 12-14; C. Hodge, Systematic Theology, II; L. Berkhof, Systematic Theology.
There are four theories of the origin of the individual soul:
Genesis 2:7 tells of God's breathing into man the breath of life (a soul) implying that He never repeated doing that after Adam. This seems to favor Traducianism, but arguments for the other alternatives have sometimes been offered based on that same Scripture.
The concept of Soul is so esoteric that there are some scholars who deny the very existence of it, partly because there has never been any concrete evidence that proves its existence. Of course, in that event, any discussion regarding the origin of the Soul becomes meaningless.
(Greek psyche; Latin anima; French ame; German Seele).
The question of the reality of the soul and its distinction from the body is among the most important problems of philosophy, for with it is bound up the doctrine of a future life. Various theories as to the nature of the soul have claimed to be reconcilable with the tenet of immortality, but it is a sure instinct that leads us to suspect every attack on the substantiality or spirituality of the soul as an assault on the belief in existence after death. The soul may be defined as the ultimate internal principle by which we think, feel, and will, and by which our bodies are animated. The term "mind" usually denotes this principle as the subject of our conscious states, while "soul" denotes the source of our vegetative activities as well. That our vital activities proceed from a principle capable of subsisting in itself, is the thesis of the substantiality of the soul: that this principle is not itself composite, extended, corporeal, or essentially and intrinsically dependent on the body, is the doctrine of spirituality. If there be a life after death, clearly the agent or subject of our vital activities must be capable of an existence separate from the body. The belief in an animating principle in some sense distinct from the body is an almost inevitable inference from the observed facts of life. Even uncivilized peoples arrive at the concept of the soul almost without reflection, certainly without any severe mental effort. The mysteries of birth and death, the lapse of conscious life during sleep and in swooning, even the commonest operations of imagination and memory, which abstract a man from his bodily presence even while awake-all such facts invincibly suggest the existence of something besides the visible organism, internal to it, but to a large extent independent of it, and leading a life of its own. In the rude psychology of the primitive nations, the soul is often represented as actually migrating to and fro during dreams and trances, and after death haunting the neighbourhood of its body. Nearly always it is figured as something extremely volatile, a perfume or a breath. Often, as among the Fijians, it is represented as a miniature replica of the body, so small as to be invisible. The Samoans have a name for the soul which means "that which comes and goes". Many peoples, such as the Dyaks and Sumatrans, bind various parts of the body with cords during sickness to prevent the escape of the soul. In short, all the evidence goes to show that Dualism, however uncritical and inconsistent, is the instinctive creed of "primitive man" (see ANIMISM).
THE SOUL IN ANCIENT PHILOSOPHY
Early literature bears the same stamp of Dualism. In the "Rig-Veda" and other liturgical books of India, we find frequent references to the coming and going of manas (mind or soul). Indian philosophy, whether Brahminic or Buddhistic, with its various systems of metempsychosis, accentuated the distinction of soul and body, making the bodily life a mere transitory episode in the existence of the soul. They all taught the doctrine of limited immortality, ending either with the periodic world-destruction (Brahminism) or with attainment of Nirvana (Buddhism). The doctrine of a world-soul in a highly abstract form is met with as early as the eighth century before Christ, when we find it described as "the unseen seer, the unheard hearer, the unthought thinker, the unknown knower, the Eternal in which space is woven and which is woven in it."
In Greece, on the other hand, the first essays of philosophy took a positive and somewhat materialistic direction, inherited from the pre-philosophic age, from Homer and the early Greek religion. In Homer, while the distinction of soul and body is recognized, the soul is hardly conceived as possessing a substantial existence of its own. Severed from the body, it is a mere shadow, incapable of energetic life. The philosophers did something to correct such views. The earliest school was that of the Hylozoists; these conceived the soul as a kind of cosmic force, and attributed animation to the whole of nature. Any natural force might be designated psyche: thus Thales uses this term for the attractive force of the magnet, and similar language is quoted even from Anaxagoras and Democritus. With this we may compare the "mind-stuff" theory and Pan-psychism of certain modern scientists. Other philosophers again described the soul's nature in terms of substance. Anaximander gives it an aeriform constitution, Heraclitus describes it as a fire. The fundamental thought is the same. The cosmic ether or fire is the subtlest of the elements, the nourishing flame which imparts heat, life, sense, and intelligence to all things in their several degrees and kinds. The Pythagoreans taught that the soul is a harmony, its essence consisting in those perfect mathematical ratios which are the law of the universe and the music of the heavenly spheres. With this doctrine was combined, according to Cicero, the belief in a universal world-spirit, from which all particular souls are derived.
All these early theories were cosmological rather than psychological in character. Theology, physics, and mental science were not as yet distinguished. It is only with the rise of dialectic and the growing recognition of the problem of knowledge that a genuinely psychological theory became possible. In Plato the two standpoints, the cosmological and the epistemological, are found combined. Thus in the "Timaeus" (p. 30) we find an account derived from Pythagorean sources of the origin of the soul. First the world-soul is created according to the laws of mathematical symmetry and musical concord. It is composed of two elements, one an element of "sameness" (tauton), corresponding to the universal and intelligible order of truth, and the other an element of distinction or "otherness" (thateron), corresponding to the world of sensible and particular existences. The individual human soul is constructed on the same plan.
Sometimes, as in the "Phaedrus", Plato teaches the doctrine of plurality of souls (cf. the well-known allegory of the charioteer and the two steeds in that dialogue). The rational soul was located in the head, the passionate or spirited soul in the breast, the appetitive soul in the abdomen. In the "Republic", instead of the triple soul, we find the doctrine of three elements within the complex unity of the single soul. The question of immortality was a principal subject of Plato's speculations. His account of the origin of the soul in the "Timaeus" leads him to deny the intrinsic immortality even of the world-soul, and to admit only an immortality conditional on the good pleasure of God. In the "Phaedo" the chief argument for the immortality of the soul is based on the nature of intellectual knowledge interpreted on the theory of reminiscence; this of course implies the pre-existence of the soul, and perhaps in strict logic its eternal pre-existence. There is also an argument from the soul's necessary participation in the idea of life, which, it is argued, makes the idea of its extinction impossible. These various lines of argument are nowhere harmonized in Plato (see IMMORTALITY). The Platonic doctrine tended to an extreme Transcendentalism. Soul and body are distinct orders of reality, and bodily existence involves a kind of violence to the higher part of our composite nature. The body is the "prison", the "tomb", or even, as some later Platonists expressed it, the "hell" of the soul. In Aristotle this error is avoided. His definition of the soul as "the first entelechy of a physical organized body potentially possessing life" emphasizes the closeness of the union of soul and body. The difficulty in his theory is to determine what degree of distinctness or separateness from the matter of the body is to be conceded to the human soul. He fully recognizes the spiritual element in thought and describes the "active intellect" (nous poetikos) as "separate and impassible", but the precise relation of this active intellect to the individual mind is a hopelessly obscure question in Aristotle's psychology. (See INTELLECT; MIND.)
The Stoics taught that all existence is material, and described the soul as a breath pervading the body. They also called it Divine, a particle of God (apospasma tou theu) -- it was composed of the most refined and ethereal matter.
Eight distinct parts of the soul were recognized by them:
the ruling reason (to hegemonikon)
the five senses;
the procreative powers.
Absolute immortality they denied; relative immortality, terminating with the universal conflagration and destruction of all things, some of them (e.g. Cleanthes and Chrysippus) admitted in the case of the wise man; others, such as Panaetius and Posidonius, denied even this, arguing that, as the soul began with the body, so it must end with it.
Epicureanism accepted the Atomist theory of Leucippus and Democritus. Soul consists of the finest grained atoms in the universe, finer even than those of wind and heat which they resemble: hence the exquisite fluency of the soul's movements in thought and sensation. The soul-atoms themselves, however, could not exercise their functions if they were not kept together by the body. It is this which gives shape and consistency to the group. If this is destroyed, the atoms escape and life is dissolved; if it is injured, part of the soul is lost, but enough may be left to maintain life. The Lucretian version of Epicureanism distinguishes between animus and anima: the latter only is soul in the biological sense, the former is the higher, directing principle (to hegemonikon) in the Stoic terminology, whose seat is the heart, the centre of the cognitive and emotional life.
THE SOUL IN CHRISTIAN THOUGHT
Graeco-Roman philosophy made no further progress in the doctrine of the soul in the age immediately preceding the Christian era. None of the existing theories had found general acceptance, and in the literature of the period an eclectic spirit nearly akin to Scepticism predominated. Of the strife and fusion of systems at this time the works of Cicero are the best example. On the question of the soul he is by turns Platonic and Pythagorean, while he confesses that the Stoic and Epicurean systems have each an attraction for him. Such was the state of the question in the West at the dawn of Christianity. In Jewish circles a like uncertainty prevailed. The Sadducees were Materialists, denying immortality and all spiritual existence. The Pharisees maintained these doctrines, adding belief in pre-existence and transmigration. The psychology of the Rabbins is founded on the Sacred Books, particularly the account of the creation of man in Genesis. Three terms are used for the soul: nephesh, nuah, and neshamah; the first was taken to refer to the animal and vegetative nature, the second to the ethical principle, the third to the purely spiritual intelligence. At all events, it is evident that the Old Testament throughout either asserts or implies the distinct reality of the soul. An important contribution to later Jewish thought was the infusion of Platonism into it by Philo of Alexandria. He taught the immediately Divine origin of the soul, its pre-existence and transmigration; he contrasts the pneuma, or spiritual essence, with the soul proper, the source of vital phenomena, whose seat is the blood; finally he revived the old Platonic Dualism, attributing the origin of sin and evil to the union of spirit with matter.
It was Christianity that, after many centuries of struggle, applied the final criticisms to the various psychologies of antiquity, and brought their scattered elements of truth to full focus. The tendency of Christ's teaching was to centre all interest in the spiritual side of man's nature; the salvation or loss of the soul is the great issue of existence. The Gospel language is popular, not technical. Psyche and pneuma are used indifferently either for the principle of natural life or for spirit in the strict sense. Body and soul are recognized as a dualism and their values contrasted: "Fear ye not them that kill the body . . . but rather fear him that can destroy both soul and body in hell." In St. Paul we find a more technical phraseology employed with great consistency. Psyche is now appropriated to the purely natural life; pneuma to the life of supernatural religion, the principle of which is the Holy Spirit, dwelling and operating in the heart. The opposition of flesh and spirit is accentuated afresh (Romans 1:18, etc.). This Pauline system, presented to a world already prepossessed in favour of a quasi-Platonic Dualism, occasioned one of the earliest widespread forms of error among Christian writers -- the doctrine of the Trichotomy. According to this, man, perfect man (teleios) consists of three parts: body, soul, spirit (soma, psyche, pneuma). Body and soul come by natural generation; spirit is given to the regenerate Christian alone. Thus, the "newness of life", of which St. Paul speaks, was conceived by some as a superadded entity, a kind of oversoul sublimating the "natural man" into a higher species. This doctrine was variously distorted in the different Gnostic systems. The Gnostics divided man into three classes:
pneumatici or spiritual,
psychici or animal,
choici or earthy.
To each class they ascribed a different origin and destiny. The spiritual were of the seed of Achemoth, and were destined to return in time whence they had sprung -- namely, into the pleroma. Even in this life they are exempted from the possibility of a fall from their high calling; they therefore stand in no need of good works, and have nothing to fear from the contaminations of the world and the flesh. This class consists of course of the Gnostics themselves. The psychici are in a lower position: they have capacities for spiritual life which they must cultivate by good works. They stand in a middle place, and may either rise to the spiritual or sink to the hylic level. In this category stands the Christian Church at large. Lastly, the earthy souls are a mere material emanation, destined to perish: the matter of which they are composed being incapable of salvation (me gar einai ten hylen dektiken soterias). This class contains the multitudes of the merely natural man.
Two features claim attention in this the earliest essay towards a complete anthropology within the Christian Church:
an extreme spirituality is attributed to "the perfect";
immortality is conditional for the second class of souls, not an intrinsic attribute of all souls.
It is probable that originally the terms pneumatici, psychici, and choici denoted at first elements which were observed to exist in all souls, and that it was only by an afterthought that they were employed, according to the respective predominance of these elements in different cases, to represent supposed real classes of men. The doctrine of the four temperaments and the Stoic ideal of the Wise Man afford a parallel for the personification of abstract qualities. The true genius of Christianity, expressed by the Fathers of the early centuries, rejected Gnosticism. The ascription to a creature of an absolutely spiritual nature, and the claim to endless existence asserted as a strictly de jure privilege in the case of the "perfect", seemed to them an encroachment on the incommunicable attributes of God. The theory of Emanation too was seen to be a derogation from the dignity of the Divine nature For this reason, St. Justin, supposing that the doctrine of natural immortality logically implies eternal existence, rejects it, making this attribute (like Plato in the "Timaeus") dependent on the free will of God; at the same time he plainly asserts the de facto immortality of every human soul. The doctrine of conservation, as the necessary complement of creation, was not yet elaborated. Even in Scholastic philosophy, which asserts natural immortality, the abstract possibility of annihilation through an act of God's absolute power is also admitted. Similarly, Tatian denies the simplicity of the soul, claiming that absolute simplicity belongs to God alone. All other beings, he held, are composed of matter and spirit. Here again it would be rash to urge a charge of Materialism. Many of these writers failed to distinguish between corporeity in strict essence and corporeity as a necessary or natural concomitant. Thus the soul may itself be incorporeal and yet require a body as a condition of its existence. In this sense St. Irenæus attributes a certain "corporeal character" to the soul; he represents it as possessing the form of its body, as water possesses the form of its containing vessel. At the same time, he teaches fairly explicitly the incorporeal nature of the soul. He also sometimes uses what seems to be the language of the Trichotomists, as when he says that in the Resurrection men shall have each their own body, soul, and spirit. But such an interpretation is impossible in view of his whole position in regard to the Gnostic controversy. The dubious language of these writers can only be understood in relation to the system they were opposing. By assigning a literal divinity to a certain small aristocracy of souls, Gnosticism set aside the doctrine of Creation and the whole Christian idea of God's relation to man. On the other side, by its extreme dualism of matter and spirit, and its denial to matter (i.e. the flesh) of all capacity for spiritual influences, it involved the rejection of cardinal doctrines like the Resurrection of the Body and even of the Incarnation itself in any proper sense. The orthodox teacher had to emphasize:
the soul's distinction from God and subjection to Him;
its affinities with matter.
The two converse truths -- those of the soul's affinity with the Divine nature and its radical distinction from matter, were apt to be obscured in comparison. It was only afterwards and very gradually, with the development of the doctrine of grace, with the fuller recognition of the supernatural order as such, and the realization of the Person and Office of the Holy Spirit, that the various errors connected with the pneuma ceased to be a stumbling-block to Christian psychology. Indeed, similar errors have accompanied almost every subsequent form of heterodox Illuminism and Mysticism.
Tertullian's treatise "De Anima" has been called the first Christian classic on psychology proper. The author aims to show the failure of all philosophies to elucidate the nature of the soul, and argues eloquently that Christ alone can teach mankind the truth on such subjects. His own doctrine, however, is simply the refined Materialism of the Stoics, supported by arguments from medicine and physiology and by ingenious interpretations of Scripture, in which the unavoidable materialism of language is made to establish a metaphysical Materialism. Tertullian is the founder of the theory of Traducianism, which derives the rational soul ex traduce, i.e. by procreation from the soul of the parent. For Tertullian this was a necessary consequence of Materialism. Later writers found in the doctrine a convenient explanation of the transmission of original sin. St. Jerome says that in his day it was the common theory in the West. Theologians have long abandoned it, however, in favour of Creationism, as it seems to compromise the spirituality of the soul. Origen taught the pre-existence of the soul. Terrestrial life is a punishment and a remedy for prenatal sin. "Soul" is properly degraded spirit: flesh is a condition of alienation and bondage (cf. Comment. ad Romans 1:18). Spirit, however, finite spirit, can exist only in a body, albeit of a glorious and ethereal nature. Neo-Platonism, which through St. Augustine contributed so much to spiritual philosophy, belongs to this period. Like Gnosticism, it uses emanations. The primeval and eternal One begets by emanation nous (intelligence); and from nous in turn springs psyche (soul), which is the image of nous, but distinct from it. Matter is a still later emanation. Soul has relations to both ends of the scale of reality, and its perfection lies in turning towards the Divine Unity from which it came. In everything, the neo-Platonist recognized the absolute primacy of the soul with respect to the body. Thus, the mind is always active, even in sense -- perception -- it is only the body that is passively affected by external stimuli. Similarly Plotinus prefers to say that the body is in the soul rather than vice versa: and he seems to have been the first to conceive the peculiar manner of the soul's location as an undivided and universal presence pervading the organism (tota in toto et tota in singulis partibus). It is impossible to give more than a very brief notice of the psychology of St. Augustine. His contributions to every branch of the science were immense; the senses, the emotions, imagination, memory, the will, and the intellect -- he explored them all, and there is scarcely any subsequent development of importance that he did not forestall. He is the founder of the introspective method. Noverim Te, noverim me was an intellectual no less than a devotional aspiration with him. The following are perhaps the chief points for our present purpose:
he opposes body and soul on the ground of the irreducible distinction of thought and extension (cf. DESCARTES). St. Augustine, however, lays more stress on the volitional activities than did the French Idealists. As against the Manichæans he always asserts the worth and dignity of the body. Like Aristotle he makes the soul the final cause of the body. As God is the Good or Summum Bonum of the soul, so is the soul the good of the body. The origin of the soul is perhaps beyond our ken. He never definitely decided between Traducianism and Creationism.
As regards spirituality, he is everywhere most explicit, but it is interesting as an indication of the futile subtleties current at the time to find him warning a friend against the controversy on the corporeality of the soul, seeing that the term "corpus" was used in so many different senses. "Corpus, non caro" is his own description of the angelic body.
Medieval psychology prior to the Aristotelean revival was affected by neo-Platonism, Augustinianism, and mystical influences derived from the works of pseudo-Dionysius. This fusion produced sometimes, notably in Scotus Eriugena, a pantheistic theory of the soul. All individual existence is but the development of the Divine life, in which all things are destined to be resumed. The Arabian commentators, Averroes and Avicenna, had interpreted Aristotle's psychology in a pantheistic sense. St. Thomas, with the rest of the Schoolmen, amends this portion of the Aristotelean tradition, accepting the rest with no important modifications. St. Thomas's doctrine is briefly as follows:
the rational soul, which is one with the sensitive and vegetative principle, is the form of the body. This was defined as of faith by the Council of Vienne of 1311;
the soul is a substance, but an incomplete substance, i.e. it has a natural aptitude and exigency for existence in the body, in conjunction with which it makes up the substantial unity of human nature;
though connaturally related to the body, it is itself absolutely simple, i.e. of an unextended and spiritual nature. It is not wholly immersed in matter, its higher operations being intrinsically independent of the organism; the rational soul is produced by special creation at the moment when the organism is sufficiently developed to receive it. In the first stage of embryonic development, the vital principle has merely vegetative powers; then a sensitive soul comes into being, educed from the evolving potencies of the organism -- later yet, this is replaced by the perfect rational soul, which is essentially immaterial and so postulates a special creative act. Many modern theologians have abandoned this last point of St. Thomas's teaching, and maintain that a fully rational soul is infused into the embryo at the first moment of its existence.
THE SOUL IN MODERN THOUGHT
Modern speculations respecting the soul have taken two main directions, Idealism and Materialism. Agnosticism need not be reckoned as a third and distinct answer to the problem, since, as a matter of fact, all actual agnosticisms have an easily recognized bias towards one or other of the two solutions aforesaid. Both Idealism and Materialism in present-day philosophy merge into Monism, which is probably the most influential system outside the Catholic Church.
Descartes conceived the soul as essentially thinking (i.e. conscious) substance, and body as essentially extended substance. The two are thus simply disparate realities, with no vital connection between them. This is significantly marked by his theory of the soul's location in the body. Unlike the Scholastics he confines it to a single point -- the pineal gland -- from which it is supposed to control the various organs and muscles through the medium of the "animal spirits", a kind of fluid circulating through the body. Thus, to say the least, the soul's biological functions are made very remote and indirect, and were in fact later on reduced almost to a nullity: the lower life was violently severed from the higher, and regarded as a simple mechanism. In the Cartesian theory animals are mere automata. It is only by the Divine assistance that action between soul and body is possible. The Occasionalists went further, denying all interaction whatever, and making the correspondence of the two sets of facts a pure result of the action of God. The Leibnizian theory of Pre-established Harmony similarly refuses to admit any inter-causal relation. The superior monad (soul) and the aggregate of inferior monads which go to make up the body are like two clocks constructed with perfect art so as always to agree. They register alike, but independently: they are still two clocks, not one. This awkward Dualism was entirely got rid of by Spinoza. For him there is but one, infinite substance, of which thought and extension are only attributes. Thought comprehends extension, and by that very fact shows that it is at root one with that which it comprehends. The alleged irreducible distinction is transcended: soul and body are neither of them substances, but each is a property of the one substance. Each in its sphere is the counterpart of the other. This is the meaning of the definition, "Soul is the Idea of Body". Soul is the counterpart within the sphere of the attribute of thought of that particular mode of the attribute of extension which we call the body. Such was the fate of Cartesianism.
English Idealism had a different course. Berkeley had begun by denying the existence of material substance, which he reduced merely to a series of impressions in the sentient mind. Mind is the only substance. Hume finished the argument by dissolving mind itself into its phenomena, a loose collection of "impressions and ideas". The Sensist school (Condillac etc.) and the Associationists (Hartley, the Mills, and Bain) continued in similar fashion to regard the mind as constituted by its phenomena or "states", and the growth of modern positive psychology has tended to encourage this attitude. But to rest in Phenomenalism as a theory is impossible, as its ablest advocates themselves have seen. Thus J.S. Mill, while describing the mind as merely "a series [i.e. of conscious phenomena] aware of itself as a series", is forced to admit that such a conception involves an unresolved paradox. Again, W. James's assertion that "the passing thought is itself the Thinker", which "appropriates" all past thoughts in the "stream of consciousness", simply blinks the question. For surely there is something which in its turn "appropriates" the passing thought itself and the entire stream of past and future thoughts as well, viz. the self-conscious, self-asserting "I" the substantial ultimate of our mental life. To be in this sense "monarch of all it surveys" in introspective observation and reflective self-consciousness, to appropriate without itself being appropriated by anything else, to be the genuine owner of a certain limited section of reality (the stream of consciousness), this is to be a free and sovereign (though finite) personality, a self-conscious, spiritual substance in the language of Catholic metaphysics.
The foregoing discussion partly anticipates our criticism of Materialism. The father of modern Materialism is Hobbes, who accepted the theory of Epicurus, and reduced all spirits either to phantoms of the imagination or to matter in a highly rarefied state. This theory need not detain us here. Later Materialism has three main sources:
Newtonian physics, which taught men to regard matter, not as inert and passive, but as instinct with force. Why should not life and consciousness be among its unexplored potencies? (Priestley, Tyndall, etc.) Tyndall himself provides the answer admitting that the chasm that separates psychical facts from material phenomena is "intellectually impassable". Writers, therefore, who make thought a mere "secretion of the brain" or a "phosphorescence" of its substance (Vogt, Moleschott) may be simply ignored. In reply to the more serious Materialism, spiritualist philosophers need only re-assert the admissions of the Materialists themselves, that there is an impassable chasm between the two classes of facts.
Psychophysics, it is alleged, shows the most minute dependence of mind-functions upon brain-states. The two orders of facts are therefore perfectly continuous, and, though they may be superficially different yet they must be after all radically one. Mental phenomena may be styled an epiphenomenon or byproduct of material force (Huxley). The answer is the same as before. There is no analogy for an epiphenomenon being separated by an "impassable chasm" from the causal series to which it belongs. The term is, in fact, a mere verbal subterfuge. The only sound principle in such arguments is the principle that essential or "impassable" distinctions in the effect can be explained only by similar distinctions in the cause. This is the principle on which Dualism as we have explained it, rests. Merely to find relations, however close, between mental and physiological facts does not advance us an inch towards transcending this Dualism. It only enriches and fills out our concept of it. The mutual compenetration of soul and body in their activities is just what Catholic philosophy (anticipating positive science) had taught for centuries. Man is two and one, a divisible but a vital unity.
Evolutionism endeavours to explain the origin of the soul from merely material forces. Spirit is not the basis and principle; rather it is the ultimate efflorescence of the Cosmos. If we ask then "what was the original basis out of which spirit and all things arose?" we are told it was the Unknowable (Spencer). This system must be treated as Materialistic Monism. The answer to it is that, as the outcome of the Unknowable has a spiritual character, the Unknowable itself (assuming its reality) must be spiritual.
As regards monistic systems generally, it belongs rather to cosmology to discuss them. We take our stand on the consciousness of individual personality, which consciousness is a distinct deliverance of our very highest faculties, growing more and more explicit with the strengthening of our moral and intellectual being. This consciousness is emphatic, as against the figments of a fallaciously abstract reason, in asserting the self-subsistence (and at the same time the finitude) of our being, i.e. it declares that we are independent inasmuch as we are truly persons or selves, not mere attributes or adjectives, while at the same time, by exhibiting our manifold limitations, it directs us to a higher Cause on which our being depends.
Such is the Catholic doctrine on the nature, unity, substantiality, spirituality, and origin of the soul. It is the only system consistent with Christian faith, and, we may add, morals, for both Materialism and Monism logically cut away the foundations of these. The foregoing historical sketch will have served also to show another advantage it possesses -- namely, that it is by far the most comprehensive, and at the same time discriminating, syntheseis of whatever is best in rival systems. It recognizes the physical conditions of the soul's activity with the Materialist, and its spiritual aspect with the Idealist, while with the Monist it insists on the vital unity of human life. It enshrines the principles of ancient speculation, and is ready to receive and assimilate the fruits of modern research.