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I. Introduction - II. Human Soul and the Cosmic Soul in Early Religions - III. The Human Soul as an Individual Substance: Plato and Aristotle. 1. Plato's Understanding of the Soul. 2. Aristotle's Understanding of the Soul. - IV.The Human Soul in Sacred Scripture. 1. Terminology. 2. "In the Image and Likeness of God" . - V. The Soul in Christian Theology, from the Early centuries to the Middle Ages. 1. The Fathers of the Church. 2. The Debate on the Nature of the Soul in Mediaeval Thought and the Contribution of Thomas Aquinas. - VI. The Human Soul and Subjectivity in Modern Philosophy. 1. Radical Dualism and the Supremacy of the Soul. 2. The Soul and the Self as a Product of Matter. - VII. The Soul in Modern Science: Evolutionism and the Mind-Brain Problem. 1. Evolutionism and Hominization. 2. The Mind-Body relationship. - VIII. The Human Soul between Theology and Science - IX. Concluding Reflections: is the Human Soul an "Action" or a "Substance"?

I. Introduction

Etymologically the Greek term psyche, "soul", derives, according to Plato, from the Greek anapnein, "to breathe," or anapsychon, "refreshing" (cf. Cratylus, 399e). Aristotle finds the root of the term, besides, in katapsyzis, "cooling" (cf. De Anima, I, 2, 405b), an interpretation incidentally used by Origen to describe the primitive fall of human spirits in terms of a cooling off of a purely spiritual reality (cf. De Principiis, II, 8). Biblical Hebrew's nearest equivalent, nefes, is linked directly with the terms "breath" or "throat." The Latin term anima (Fr. âme; Sp. alma) derives either from the Greek anaigma, "without blood," or more likely from anemos "wind," or "breath." The German form Seele and the English "soul" from the Old German saiwolò, is probably of the same origin as the Greek aiolos, "mobile," which designates a self-moving principle. The Sanskrit term Atman, typical of the Rig-veda, also means breath, and appears in modern German as atmen, "to breathe."

The term "soul," in its different forms and expressions, is to be found in virtually every period of history, every civilization, every philosophical anthropology, every religious understanding (cf. Eliade, 1987). It is, then, a concept that crosses human thought and experience of all the ages. Nonetheless, philosophers have always been aware of the difficulty of speaking about the soul in rigorous terms. Thomas Aquinas states that "It is very difficult to know what soul is" (cognoscere quid sit anima difficillimum est, De Veritate, q. 10, a. 8, ad 8um), and affirms that to know the soul "requires a proper and careful investigation" (requiritur diligens et subtilis inquisitio, Summa Theologiae, I, q. 87, a. 1). Two principal yet clearly opposed understandings of the human soul are to be found throughout the history of philosophy: the so-called "spiritualist" position (Pythagoras, Plato, Plotinus, Augustine, Descartes, Leibniz, etc.), and the "materialist" understanding (Epicurus, Lucretius, Marx, Comte, Engels, etc.). The first draws on a variety of aspects of human life and behaviour, usually linked with religion and ethics (self-awareness, self-transcendence, freedom, communication, dialogue, culture, creativity, etc.), and usually involves a dualistic anthropology. The second line is more at home in a strictly scientific and rational discourse, and tends towards a monist anthropology. Some authors, such as Thomas Aquinas, managed in many ways to synthesise the two approaches.

Scientific discourse in recent centuries has generally become circumspect in speaking of the existence and attributes of a human "soul," understood as a kind of invisible, immaterial, unifying element at the core of the human being. The development of physics, chemistry, biochemistry, biology and experimental psychology has witnessed if not occasioned a progressive decline in the use of the term, or at best, its being reserved for symbolic or poetic usage. In recent decades however the tide has been turning again, especially as scientists have come to realise the significance and usefulness of the concept in studying the so-called "mind-body problem."

II. Human Soul and the Cosmic Soul in Early Religions

Among primitive peoples the term "soul" is spoken of for the most part in cosmological terms, that is within an attempt to understand the unity of the universe (cf. Lévy-Bruhl, 1927; Rohde, 1891). However contrary to the positions of 19th century authors (cf. Tylor, 1871; Zeller, 1883, pp. 30-33), it would seem that Presocratic reflection on the human soul is not driven primarily by our understanding of the cosmos, but rather by that of the relationship between the Divinity and humans (cf. Joël, 1906; Marett, 1929). In other words, primitive understandings of the soul are religious and ethical rather than cosmological and scientific. That is to say, the Presocratics look on the soul not primarily in physical and cosmological terms, but in anthropological, intuitive and mystical ones. The notion of "soul" as equivalent to "fire" or "breath" is common among many peoples; understandably, death ensues and expresses the soul's flight or absence. Greek philosophers of the naturalistic school such as Diogenes, Anaximander and Anaximines identified the soul with "air"  and  "breath." For Heraclitus, the soul is subtle and deep, and best described in terms of fire. For atomistic materialists such as Democritus, Epicurus and the Stoics, the soul is composed of refined and mobile atoms, and is mortal at an individual level. Yet it is an element of the living organism of the cosmos. The earliest expressions of the term are to be found in the writings of Homer (cf. Arbman, 1926; Hasenfratz, 1986; Pohlenz, 1947; Porcarelli, 1998; Rohde, 1891). Vital human processes such as thought, sentiment, sensation and consciousness are attributed by the poet to the tangible thymos. The term is linked to notions such as drive, courage, pleasure, fury or impulse, and though akin to fumus in Latin, it is commonly translated as animus . Conversely, the less frequently used term psyche is commonly reserved in Homer to designate life in general, the vital though intangible energy which both humans and animals possess impersonally, the cosmic power made up of breath, blood, life etc., over which humans exercise no dominion. With time, however, the unconscious psyche comes to coincide with the sentient thymos and to include the latter's main properties: consciousness and spiritual individuality. This fusion between breath and consciousness, brought to completion by the Orphics, is what made it possible for the Presocratics to speak of the transmigration of souls, and as a result of the survival, independence and immortality of the human soul, which comes to be considered fully itself only when dreaming, or at the moment of death.

The idea of the individual conscious human soul (Gr. thymos) as the direct expression and presence of the "in-forming" power of the common, unconscious, cosmic soul (Gr. psyche), relates closely to the doctrine of the unitary origin of the world, and points in turn to its primitive formation by the gods (Moreau, 1981). This tradition is typical of Pythagorism, whose mythology attempts to describe the origins of the universe on the basis of numbers which express both synthesis and harmony. Pythagorism is taken up by Plato who explains that the ordering of the primitive chaos is attributed to a "cosmic soul", which is "the most excellent of all things engendered by the best of all eternal intelligible beings" (Timaeus, 37ab). The same theory is to be found among the Stoics and Neoplatonics, especially in Philo and Plotinus, and is often termed "emanationism". According to Plotinus, the One gives rise to the Intelligence (Gr. nous), which in turn gives rise to the cosmic soul (Gr. psyche), which contains the "seminal reasons" of all things. It may be noted that the notion of "cosmic soul", as well as the concomitant theories of emanation and pantheism, have arisen occasionally in a Christian context. Theodore of Chartres and William of Conches, for example, considered that the cosmic soul may be identified with the Holy Spirit, an idea also found among Neoplatonics. Giordano Bruno took it that it is present as a principle of life in all beings. In an idealistic and pantheistic context Friedrich Schelling defines the cosmic soul as what sustains the continuity of the organic and inorganic world, and unifies nature in a single universal organism.

It is quite clear however that the Judaeo-Christian doctrines of creation ex nihilo and the special creation of man would eventually come to explain the origin, nature and destiny of the soul in quite different terms. The description of the human soul as an emanation of the cosmic soul has, in fact, two principal drawbacks. First, it is not in a position to express or defend the dignity of the individual human being, since just as the individual soul is derived from the cosmic soul, humans in their multiplicity of microcosmoi are ontologically subordinated to the unitary cosmos in general. Second, drawing as it does on a vitalistic, mythological and intuitive epistemology intent on explaining the origins and dynamism of the universe, it stands in need of more serious rational or scientific verification. Plato and Aristotle contributed decisively in this process of clarification.


Reflection on the existence and origins of the human soul among primitive peoples, as we have seen, is cosmological, at least if taken from a descriptive standpoint. Nonetheless it is decisively motivated by an ethical and religious view of the world, involving individual immortality and ethical responsibility. These elements are central in the consolidation of the notion of the "substantiality" of the human soul, which was one of the principal legacies of the golden age of Greek philosophy. The consolidation of a more substantialist understanding of the individual human soul took place historically in two main directions. First, in a primarily ethical and religious context, Plato developed an anthropology of the human composite, body and soul, that was decidedly "dualistic" in character: body and soul cohabitate as it were, but are at heart antagonistic to one another. Second, in a largely rational, empirical and metaphysical context, Aristotle developed an understanding of man involving a "substantial unity" between body and soul.

1. Plato's Understanding of the Soul. Plato (427-347 B.C.) received the notion of the purification and salvation of the soul from the Orphic sects, through Pythagorism. Souls are considered to be of celestial origin, particles broken off the infinite Spirit (Gr. pneûma) that enter material bodies in order to breathe. Given their heavenly origin, souls, if they live upright lives and attain complete purification will eventually be reintegrated into their primitive spiritual origin. If they live unworthy lives, however, they will be reincarnated as often as necessary in the bodies of plants or animals until they have undergone full purification. Though certain cosmological elements remain in his reflection, Plato's understanding of the soul is situated principally in an ethical and religious context. This is confirmed by the idea that soul and body are fundamentally antagonistic, and the former "enters" the latter as the result of a primitive fall or sin (cf. Phaedrus,  248ff; Republic, VII, 514ff).

Plato attributes four properties to the human soul. a) The soul is the "principle of life". While every body moved from without is inanimate, every body that moves from within by itself and for itself is animate. Every aspect of reality is regulated, as it were, by its own soul. The sun, the stars, the earth all have their own (cf. Laws, 898d). b) The soul is "immaterial." What is proper to the soul is thought, and by it the soul relates to the intelligible world. Significantly Plato rejects the theory of Pythagoras (570-490 B.C.), according to whom the soul is the simple result of the harmony (Gr. krásis) among the elements (Cf. Phaedo, 93b). Moreover, human soul is composed of three parts: the rational soul, situated in the brain and destined to direct superior human activities; the passional soul, situated in the thorax and source of the noble passions; and the concupiscible soul, in the abdomen, source of the gross appetites (cf. Republic, 441c). c) The passional and concupiscible parts of the soul are mortal, while the rational soul is of itself immortal and eternal. "Of all the things man possesses, his soul is the closest to the gods, and its properties are most divine and true" (Laws, 726a). In the Phaedo, Plato offers a series of reasons to account for the soul's immortality: the analogy with the cyclical rule of natural things (just as death follows on from life, so also life must follow on from death); humans know in the present moment by reminiscence or recognition what they once saw in a previous existence and this would be impossible were the soul not immortal; the soul, on account of its simplicity and affinity to the celestial ideas, is immutable and pure, and thus imperishable, whereas the body and everything composed corrupts and dissolves (cf. Phaedo, 70-80; Republic, 608-611). d) The soul "precedes" the body with which it is united in an accidental and not entirely natural way, as a pilot to a ship, or a rider to a horse (cf. Phaedo, 246a, 247c). In that sense the body is not fully human: man is his soul; man is a soul using a body (cf. Alcibiades Major, I, 130a-131a).

Plato's ideas were taken up frequently throughout the history of thought, especially by the Neo-Platonic thinkers Plotinus (205-270) and Porphirius (233-305). Plato's understanding of the soul has been enormously influential over the centuries for several reasons. It expresses a way of thinking in consonance with the basic thrust of many other world views, particularly with Oriental ethical and religious philosophies (Eliade, 1987), and has the merit of rationally enhancing pre-critical and intuitive descriptions of the soul, giving them a metaphysical basis. From the ethical and religious standpoint, it certainly offers a coherent and enduringly attractive account of the origin and nature of the soul. However its drawbacks are not easily overcome, mainly because the strictly anthropological and metaphysical underpinnings of Platonism are constantly put under strain by its inherent dualism and the scarce attention it pays to the human body, to matter and the findings of science. Platonism defends the immortality and dignity of the human individual, certainly, but the presence of humans (of human souls) in the world, and their relationship to the cosmos and to other humans remains clearly problematic. It is not surprising to find that Plato accords slight value to empirical data in general, since the latter draws on the material and corruptible side of reality. Understandably, the exact sciences play little or no role in the development and consolidation of his doctrine of the human soul (cf. Phaedo, 65-67). It is at this point where Aristotle's contribution comes in.

2. Aristotle's Understanding of the Soul. After an early understanding of the human soul close to Plato's dualistic vision, and then an intermediate period of "vitalist instrumentalism," which holds an accidental though not antagonistic union between body and soul (cf. Inciarte, 1984; Nuyens, 1973), the definitive position of Aristotle (384-322 B.C.) is found in his work De Anima, deeply influenced by his scientific findings and cognisant of the psychosomatic unity of the human being. Here Aristotle speaks unhesitatingly of a direct union between the body and soul, in such a way that the soul is said to be the "substantial form" of the body. Of this work Hegel said that "it is the best and perhaps the only speculative work on this subject [the soul]" (Encyclopedia of Philosophical Sciences, § 378).

Aristotle begins by affirming that «the soul is that by which in the first place we live, feel, move and understand», and adds that "it cannot be either without the body, or be a body, because it is not a body, but something of the body" (cfr. De Anima, II, 2, 414a). It is the first principle of corporal living beings, though distinct from matter; it is the source of the body's life. The soul "is the first act and the final act (Gr. enteléchia) of the natural body which is in potency to life" (De Anima, II, 1, 412a). Thus the soul can be considered either as an "entitative principle" which constitutes a living organism out of a potentially living body, or as an "operative principle," or source and root of all the vital acts of the organism. According to Aristotle, there are three kinds of "soul" informing matter: the vegetative soul, principle of nutritive, growth and reproductive actions; the sensitive soul, origin of knowledge, appetite and sensitive movement; and the rational soul, principle of rational knowledge and attraction. For him it would be incorrect to say that the soul lives, but rather that the entire human being lives in virtue of the soul (cf. Metaphysics, VII, 11, 1037a).

As regards the spirituality and immortality of the soul, Aristotle holds that in humans there are intellectual operations which only a separated (and therefore incorruptible) substance (Gr. noûs, as opposed to sôma) is in a position to accomplish (cf. De Anima, III, 4, 429a-b). However, natural "forms" are not separated substances, and must perish when the composition of matter and form disintegrates. What happens then when humans die? On the basis of Aristotle's writings it is not completely clear whether or not the "agent intellect" (which according to De generatione animalium, 736b is of divine origin, as well as being separate, unmixed and impassive) is present and active as an distinct and immortal enteléchia for each human being (cf. Reyna, 1972).

Doubtless the doctrine of Aristotle, insisting as it does on the substantial unity of the human being, attempts to respect empirical data to the full. But it does not easily explain how individual human beings can acquire any kind of meaningful immortality, nor does it deal with the question of human self-consciousness. Even though his earlier writings, closer to Plato's, referred to questions of an eschatological kind, the fact is that Aristotle spoke little of such issues in later works. Understandably, scientifically-inspired monistic or atheistic materialisms that question human immortality have commonly drawn on Aristotle's writings. Could it be that Socrates was right after all in holding that science is simply incompatible with religion (cf. Phaedo, 65-67), empirical data with the love of wisdom?

After examining Plato and Aristotle, it should now be clear that our understanding of the human soul is significantly conditioned by that of the human body, and vice versa. A clear point of conflict is to be found in the area of human mortality. For Plato, whose religious ethics impel man towards immortality, death is considered a release, an unshackling of the soul from the dead weight of matter. For Aristotle, whose empirically-based metaphysics ties man to the tangible and material world, death seems to involve the destruction of nature and the elimination of the individual, though he does not reject the possibility of an eschatologically immortal soul (cf. Metaphysics, XII, 3 1070a). It is precisely in the area of death and immortality that Judeo-Christian revelation made its probably most lasting contribution to anthropology, and thus to our understanding of the human soul.

IV. The Human Soul in Sacred Scripture

1. Terminology . Sacred Scripture uses three closely linked Aramaic terms when speaking of the human being: basâr, that is, "flesh" (translated as sarx in the Greek version of the LXX), nefes, "soul" (Gr. psyché), and rûah, "spirit" (Gr. pneûma) (cf. Gundry, 1976; Lys, 1959; Wolff, 1973). All three refer to the entire human being. Basâr denotes weakness, dependence and corruptibility, nefes indicates the concrete human vitality of the individual, and rûah or spirit, while also referring to the "soul," points above all to the divine source of all life. Thus the human being "is" basar and nefes, and "receives" ruah. The term nefes, the nearest Biblical equivalent to "soul," found about 750 times in the Old Testament, refers to a "being that breathes" (cf. Ex 23:12; 31:17; 2Sam 16:14), understandably so, for its etymological root is very close to the term "throat" and "mouth" (cf. Gn 37:21; Ps 107). Nefes is likewise associated with the "blood" (cf. Lv 17:11; Dt 12:23). Respiration, of course, and blood are both tangible signs of life. Later Old Testament writings regularly use the term nefes to designate both life and the individual human being, and it is applied about 70 times to the individual or person. Man becomes a living nefes in receiving the "breath of life" from God (Heb. nismat; cf. Gn 2,7). It is interesting to note how the in the Targuminin the text of Gn 2:7 is translated as follows: «and man became a talking being». Nefes likewise refers to a variety of manifestations of human life, especially of an interior kind: passions, affections, desires. In fact it becomes almost an equivalent to the "interiority" of the human being, the seat of all human affections: of thought and knowledge (cf. Ex 23:9; Jb 16:4; Prv 12:10), of joy (Ps 85:4), of fear (Is 6:4; Is 15:4), of piety ( Ps 85:4; 103:1.35; 142.8), of confidence (Ps 56,2) and of memory (Dt 4,9). The statute of "the dead" in the Old Testament is not far from what is common in many religious world-views of the same period. The dead (indicated by the Hebrew plural noun repa'îm) descend into the underworld or se'ol (which is not to be identified with the tomb in which the corpse is deposited) and remain there in a lethargic, somniferous, collective, inactive state, incapable of praising or invoking God, whose power does not reach them (cf. Pozo, 1980, pp. 200-210)

The term "soul" or "spirit" is also to be found in the New Testament in a variety of usages (cf. Schweitzer et al., 1984). Like in the Old Testament, the Greek term psyché indicates the psychical life referred to the soul or to the individual (cf. Lk 2:35; At 2:43 and 15:24; Rom 2:9; 2Pt 2:8), also used by Jesus (cf. Mk 14:34). In the very moment of his his passion, Jesus' soul is "sorrowful even to death" (Mk 14:34). The term spirit is also widely used (pneûma) and referred to the personal interiority (cf. Mt 5:3; At 17:16; 1Cor 2:11; 2Cor 2:13; Heb 12:23), though most of the passages speaks of it insofar as in relation to the divine Spirit, especially in the Pauline writings (cf. Rom 1:9 and 8:10.16; 1Cor 6:17; 2Cor 12:18; Gal 6:18; but also Lk 1:80; At 18:25). It remains clear that pneûma is different from psyché, the same as rûah differs from nefes (cf. 1Ts 5:23; Heb 4:12). Dying on the cross, Jesus "bowing his head, handed over his spirit (pneûma)" (Jn 19:30).

2. "In the Image and Likeness of God" . The anthropological content of the Scriptural terms nefes, basâr and rûah, approximate Hebrew equivalents of "soul," "flesh" and "spirit," is quite similar to that of other religious and philosophical world-views of the same period (cf. Wolff, 1973). The terms do not, in other words, express a completely distinct and clearly identifiable biblical anthropology and understanding of the human soul. The truly distinctive elements of biblical anthropology do not provide so much a description of the "nature" of man on his own, but rather of his "interpersonal" relationship with God. More attention, for instance, should be addressed to the term heart (Heb. lêb). Theologically speaking, the critical terms include creation, covenant, salvation etc. The cutting edge of biblical anthropology is not to be found in the everyday terminology describing the natural makeup of human beings, their life and actions, but above all in man's special statute as one "made in the image and likeness of God" (Gn 1:26), as "person" (cf. O'Callaghan, 1999).

Many Fathers of the Church, among them Clement of Alexandria, Origen and Athanasius took it that the "image and likeness of God" is to be found imprinted principally on the human soul, centre of the human intellect and will, in keeping with some of the fundamental intuitions of the Neoplatonists and Stoics (cf. Grossi, 1983; Hamman, 1987). This position was followed in general terms by many authors, among them Augustine and Thomas Aquinas. However it would be mistaken to take the "image and likeness of God" present in the soul as if the latter could be considered apart from the body. It would be more correct to say that the notion of "image and likeness", referring as it does to the entire human being, is what explains the true role, nature and purpose of the soul, rather than the other way around. In spite of the fact that the term "image of God" is not applied frequently to humans in Scripture (it appeares in Gn 1:26-27 e 9:6; Wis 2:23), Christian anthropology has always accorded it considerable value (cf. Westermann, 1984, pp. 147-161). This is the case mainly because Jesus Christ, God's own Word made flesh, who died and rose from the dead, is considered to be the "perfect Image of the Father" (cf. 2Cor 4:4; Col 1:15; Heb 1:3; 2:6-9). This Christological reading of the image is confirmed by Church Fathers such as Ireneus (cf. Epideixis, 71), Tertullian (cf. De resurrectione carnis, 6, 3-4), Clement of Alexandria (cf. Paedagogus, I, 98, 3), Athanasius (cf. Contra Arianos 3, 10-11) and others. All Christian anthropology, in other words, is at heart an "implicit Christology."

Four observations could be made on the term "image and likeness" as applied to humans. a) In the Old Testament texts employing the term "image and likeness" principally understand it in terms of human dominion over, or embassy to the world. No longer is the human seen as the product of a sort of "cosmic soul." Human superiority over the land, the sea, the stars and the animals is proclaimed by his being called and capacitated to exercise dominion over, and take care of, the rest of creation. Man is God's prime representative or ambassador on the earth. b) Being made in the "image and likeness" of God can also be seen to express the social character of humans and the unity of the human race. The activity of the human soul does not find expression in solitude and contemplation alone, but in communion with others, and fundamentally with God. c) Genesis speaks of man made "in the image and likeness of God" in terms of a promised immortality (cf. Gn 9:6-7; Wis 2:23). d) All these characteristics of the human being are not considered as mere static properties possessed once and for all, but are destined to express themselves and mature on the basis of having received their power and energy from the creating, life-giving God, without in any way being confused ontologically with Him (man is not "in the image" of God, but is "made in the image" of God.

Concerning the relationship between soul and immortality, it must be understood in the light of the biblical doctrine on the origin and nature of death itself (cf. Pozo, 1980). Death is not considered truly a part of the God's plan for man, who destined him to immortal life, and to communion with Himself, with nature and with others. Death came into the world not by the nature of things, but historically, as a result of human sin (Gn 3:17-19; Wis 1:13-14; 2:23-24; Rom 5:21; 6:23), and it will be totally eliminated at final resurrection (1Cor 15:54-5), promised in the Old Testament and made present definitively in Jesus Christ, Lord and Saviour of mankind, who died and after three days rose again from the dead (see Resurrection). From the standpoint of the understanding of the soul, the Scriptural understanding of death offers a important clarification: the soul, should it eventually exist separated from the body, would do so as it were in unnatural and temporal circumstances, in view of final resurrection.


1. The Fathers of the Church . On the face of things, Christians, at least during the first centuries, took a greater interest in ethics and religion than they did in the findings of science and its implications. This is manifested in a generalised acceptance of Platonic anthropological categories which express a net distinction between soul and body. Platonism was considered to be more pliable to Christian revelation and reflection than Aristotle's thought, since it focused on upright human behaviour and asceticism, on eternal reward for the individual who is faithful to God, though it contains a somewhat pessimistic attitude to a world in urgent need of being saved. It would be mistaken however to consider early Christianity in a dualistic light, and this for distinctly theological reasons. Body-soul "dualism" —whether of a Platonic or Gnostic variety— speaks of a double origin to the universe, unthinkable in a Judaeo-Christian monotheistic context. Body-soul dualism tends to identify matter with nothingness (Plotinus) or with evil (Mani, Priscillian), which is clearly contrary to faith in a free creation by a loving God of all things ex nihilo. The doctrine of the Resurrection of Christ, and its promised extension to believers at the end of time, completely obviates any essential antagonism between body and soul. It is understandable therefore that Christian writers from the beginning unanimously held to the fundamental unity of the human being (cf. Orbe, 1967; Fernández, 1979). Two principal expressions of this doctrine are to be found (cf. Greshake, 1986, pp. 108-127; Grossi, 1983, pp. 11-84), that of the school of Antioch, insisting on the formation of humans from the dust of the earth and emphasising primarily the unity of the human being; and that of the Alexandrian school, considering the spiritual soul as the defining element of the human composite. The same basic arguments recur throughout the Middle Ages, right up to the Council of Vienne held in 1312.

According to Justin Martyr (2nd century), man is an ánthropos sarkikós (cf. De resurrectione, 7), naturally in the flesh. He asks: "Is man to be identified with the soul on its own? No, it is the soul of man. Is the body man? No, it is man's body. Neither of them is of itself man, who is a rational animal. Man is the result of the composition of both" (De resurrectione, 8). Athenagoras (II century) spoke in the following terms: "every human nature is made up of an immortal soul and a body adapted to it in the moment of creation; it was not the soul alone, nor in separation from the body, to which God destined creation and life... but rather to humans, composed of body and soul... A single living being is formed out of body and soul, a being which suffers as much as the soul and the body suffer" (De resurrectione, 15). In opposition to the Gnostics who denied final resurrection and considered that matter had been created by the devil, St. Iraeneus of Lyons (135-202) emphasised the original goodness of the flesh and developed this doctrine in strictly Christological terms (cf. Epideixis, 71; Adversus Haereses, V, 28). Tertullian (160-215) follows Iraeneus' Christological approach, extending it to the sacramental realm, in an audacious Christian "materialism" clearly opposed to the Gnosticism of Valentinus. Caro cardo salutis, he declares, "the flesh is the hinge of our salvation" (De carnis resurrectione, 8). As a result, though in man both body and soul are present, neither component can be said to be prior to the other. Conversely, authors of a more Platonic bent such as Clement of Alexandria, Origen and Gregory of Nyssa in the East, and Lactantius and Augustine in the West, gave priority to the soul in explaining the origin and dignity of the human being. Though in no case do these authors deny the true unity that binds body and soul, human specificity is defined in terms of the soul.

In the anthropology of Origen (185-253), the predominance Plato gives to the soul is also present. His systematic opposition to the Gnostics doea not bring him, however, to insist on the divine origin and dignity of matter as Iraeneus did, but above on all the freedom and responsibility of individual humans in the original fall. Many Gnostics considered the tyrannical power of matter to be such, that humans had been virtually constrained to sin and slavery. Origen however had no doubt but that God had created matter, but had done so in order to punish wayward souls.

Openly opposed Manichaeistic dualism in respect of matter, Augustine (354-430) drew considerably on the doctrine of Plato. "The better part of man is his soul -he says- the body is not all man, but the inferior part of man" (De civitate Dei, XIII, 24). Nonetheless Augustine does reject the Platonic notion of the pre-existence (or native divinity) of the human soul, and its temporal precedence over the body. As regards the origin of the soul, he accepts neither Plotinus' emanationism, nor Origen's doctrine of the simultaneous creation of souls at the beginning of time. The theology of original sin and its transmission inclines him towards the theory of "traducianism," popularised by Tertullian, according to which the souls of children are drawn from that of their parents and not from God. Yet he remains undecided between this and the theory of "individual creationism" (first taught by Lactantius, cf. De opificio Dei, 19, 73) which with time become the doctrine most commonly accepted by Christians. For Augustine, in fact, body and soul are mutually necessary elements of the human composite. The human being is not the body alone or the soul alone; when both are united at the same moment, then there is man. "It would be false —says Augustine— to say that man consists of the mind (Lat. mens; Gr. noûs), and add that what is in the flesh is not man" (Sermones, CLIV, 10, 15). It is clear however that Augustine envisages the union between body and soul in terms of a hierarchical and dynamic interaction. He states that man is a rational soul that uses a mortal and earthly body. Analogously, to feel is not proper to the body, but rather to the soul by the body; neither does the body feel, but the soul feels by the body (cf. De Genesi ad litteram, III, 7).

Official Church statements over the patristic period regarding anthropology in general and the soul in particular vouch for the divine origin of both body and soul, and, in the context of creation, man and evil, oppose the principal tenets of Gnosticism. The following points are relevant. First, the human soul is neither part of or an emanation of the divinity; neither does it derive from the divine substance (cf. DH 190, 201, 285, 455, 685), but is created by God immediately (Lat. immediate), that is directly, without intermediaries (cf. DH 190, 360; a teaching affirmed again by Pius XII's Humani generis, cf. DH 3896), and ex nihilo from nothing pre-existing (cf. DH 190, 360, 685). Souls do not pre-exist ab aeterno, as Origen suggested, nor do they become enclosed in a body in punishment for their sin (cf. DH 403, 456). Second, the Church professes the original goodness of "matter", of the body and of the world, insofar as it is all created by God. Many Gnostics considered in fact that the devil created matter and wages war on humans (on the human soul) through the body. As a result they often considered marriage and procreation as the work of the devil. The Church consistently rejected these teachings, for example at the Council of Braga in 561, and at Lateran Council IV (1215) and the Council of Florence (1442) (cf. DH 457-463, 802, 1333, 1336). Third, the unity of body of soul is expressed in three ways: a) in terms of the oneness of divine creating action by God, «creator of all things, seen and unseen» (DH 150); b) on the basis of the doctrine of final resurrection "of the same flesh" (DH 72; 76; 325; 540; 574; 684; 801); and c) on the basis of the "hypostatic" union that unites in the person of the Word the divinity and perfect humanity of Christ, made up of body and rational soul: "sicut anima rationalis et caro unus est homo, ita Deus et homo unus est Christus" (DH 76).

2. The Debate on the Nature of the Soul in Mediaeval Thought and the Contribution of Thomas Aquinas . Christian anthropology during the Patristic period is Christological in approach, though linguistically and conceptually Platonic. Things change somewhat during the Middle Ages. In rather simplistic terms it may be said that Christology and Platonism are replaced, respectively, by eschatology and Aristotelianism (cf. Wicki, 1954). The question being asked here relates to the anthropological implications of the eschatological salvation won by Christ: how can a part of the human composite survive death?, and, how is the body saved?

In the early Middle Ages, under the influence of Augustine, the approach of St. Bonaventure (1217-1274) and Hugh of St. Victor (1096-1141) is still decidedly Platonic. According to Hugh of St. Victor, God has created the soul and not the body in his image and likeness; that is why it is immortal; yet on account of its union with the soul, the body partakes in the latter's immortality as a beneficium creationis . Body and soul are complete substances, accidentally united to one another, and the separated soul therefore may be considered as a person in its own right. And just as the body did not give the soul its personal being in being united with it, neither will it take it away when it corrupts at death. As a result, final resurrection is of slight theological import. The decisive twist comes, however, with the introduction of Aristotle's thought through the agency of his Arabic commentators such as Averroes, Avicenna and Maimonides whose influence made itself felt during the 1200's. Gilbert de la Porrée (1080-1154) and William of Auvergne (1180-1249) consider the human being in a more harmonic way, following the Aristotelian perspective of the soul as the form of the body: the soul is to the body what form is to matter. The "in-forming" role of the soul is considered essential both to its own nature and to the body which it constitutes as human. The apparently insuperable tension (cf. Dales, 1995) between the Aristotelian doctrine of substantial union between body and soul, and the Platonic vision of the immortality of the soul and its metaphysical independence from the body, is given a decisive clarification, if not a definitive solution, by St. Thomas Aquinas (1225-1274) (cf. Bertola, 1973; Moreau, 1976; Lobato, 1987; Pegis, 1974 and 1976).

It should be noted that Aquinas attempted to overcome the tension between the Platonic and Aristotelian tendencies for theological and Christian reasons (cf. Summa Theologiae, I, q. 75; for issues related to the human soul see the qq. 75-90). The human soul is the form of a body because of the kind of substance it is, he says (we note that the term "substance" must be understood as something that exists per se). It is not a pure spirit, nor a separated substance, but an intellectual substance that informs, "shapes" or configures the body. The novelty introduced by Aquinas over the teaching of Aristotle was as follows: whereas the latter considered non-divine substances as composed generally speaking of "matter" and "form", the former considered each substance as a composition of essence and the individual "act of being" (Lat. esse, existence). In every creature there is a composition between potency and act: both Aristotle and Aquinas accept that. Yet according to Aquinas the act need not correspond in every case to a particular substantial form, nor potency to matter, as Aristotle thought. The soul is a substance, in that it is composed of essence (that of a spiritual form) and act of being deriving directly from the divine creating action. This gives man full metaphysical individuality or incommunicability (cf. Summa Contra Gentiles, book II, ch. 75; De Unitate Intellectus contra Averroistas, n. 2), a teaching Aquinas insisted upon against commentators of Aristotle such as Averroes, who in a sense had attempted to "platonise" Aristotle (cf. Fabro, 1955, p. 269). Besides, since it includes no materiality in its own structure, the soul is simple and incorruptible. "The body is not united to the soul accidentally, because the very being of the soul is also the being of the body, thus being common to both" (Quaestio de anima, a. 1, ad 1um). In technical terms, it can be said that the soul communicates being to the body at the level of formal, not efficient causality.

The question Aquinas faced was the following one: can an incorruptible spiritual substance be the form of a corruptible body, constituting with it a substantial unity of being (cf. Summa Contra Gentiles, book II, ch. 56)? His reply is in the affirmative, for the soul's very purpose is to communicate the being by which it subsists to the body (cf. ibidem, chps. 68-72). The following observations can be made. a) The rational soul is the form of the body not through its potencies and virtualities as Avicenna held, but by its very essence. Though subsistent, it is proper to the soul to "inform" the body, and it stands in need of the body for its own perfection (cf. Summa Theologiae, I, q. 51, a. 1). b) The rational soul is the one and only form of the human body, being at one and the same time vegetative, animal and rational. By a single act of being the human soul is the form of the body and of all its functions. Thus there are no intermediaries of any kind between the body and the soul. The fact that a particular human being does not exercise all its faculties only means that they are in potentiality to their acts; the situation is different with God, for whom the power of acting and act itself are identical with the divine substance. c) The soul as such does not exist prior to the body, though it is metaphysically prior to the body in that it is a form that is independent of the body as regards its being. This is what makes it possible to speak of the "incorruptibility" of the soul (Aquinas speaks of "immortality" regarding the human being insofar as he participates in the divine life through the gift of grace). Aquinas demonstrates the incorruptibility of soul not on Platonic but on distinctly Aristotelian premises. The soul can, potentially, know all things material, and can transcend itself, since it must be immaterial and thus incorruptible (cf. Summa Theologiae, I, q. 75, a. 6; cf. Foster, 1993). d) The separated soul is neither a man nor a person. After death it retains a natural tension (Lat. commensuratio) towards "its" body, so that the soul united to the body is more like God than when separated from the body, because it possesses its nature more perfectly (cf. De Potentia, q. 5, a. 10, ad 5um).

Aquinas was aware of the need to insist both on the metaphysical priority of the human soul, and its substantial unity with the body, according to the formula anima forma corporis. He did so: a) for theological reasons, to avoid that any body/soul duality or considering matter as an independent co-source of human existence, would compromise the oneness and simplicity of the creating work of God; b) for anthropological reasons, wishing to avoid the Averroist position which would have seriously compromised the individuality and dignity of each human being by reducing human immortality after death to absorption into a common separated substance; and c) on the basis of a healthy trust in the reliability of empirical observation and scientific discourse. However, two points still remained unclear in Aquinas' view: the unicity of the human soul, and the statute of the separated soul.

After the death of Aquinas (1274), the bishop of Paris Stephen Tempier and, later, the archbishop of Canterbury Robert Kilwardby and his successor John Peckham, rejected as false the Thomistic thesis of the unicity of the soul, they all maintaining the existence of three different souls in the human being. The "plurimorphic hypotheses," that in real terms came closer to Plato than to Aristotle, was followed by most of the scholars of that epoch, among them the leader of the Franciscan "spiritual" faction, Pier di Giovanni Olivi. The plurimorphic theories, however, in spite of appearing to resolve certain difficulties, had one weak point: they were unable to explain and guarantee the unity of the human being, for an accidental union can only give rise to several distinct substances. As a result authors such as Richard Knapwell and John of Paris began to repropose Aquinas' theory of the soul as the unique form of the body, insisting that body and soul are not truly distinct realities. Finally, Aquinas' position was taken up at the Ecumenical Council of Vienne in 1312, which states that "substantia animae rationalis seu intellectivae, vere, per se et essentialiter humani corporis forma - the soul truly, of itself and essentially is the unique form of the human body" (DH 902). The doctrinal point of departure of this statement is at heart Christological: the same conciliar decree taught against Olivi that the unity/oneness of the saving humanity of Jesus Christ is what points to the substantial unity of human beings in general (cf. DH 900).

It is easily to understand that Aquinas' position concerning the situation of the soul, once separated from the body, remained unclear. Thomas himself was keenly aware that after death the separated soul does not fulfil its essential purpose, that of "in-forming" the body. Averroists at Padua kept insisting that there is only one, common, immortal intellect. Conversely, followers of Alexander of Aphrodisias such as Peter Pomponazzi claimed that man has no immortal intellect. According to Pomponazzi (1462-1525), intellectual operations depend indeed on the body, but this does not mean there exists an independent intellectual substance. In different directions both schools (Averroists and followers of Pomponazzi) came to deny personal immortality. However, Pope Leo X, with the approval of the Fifth Lateran Council (1513), rejected the proposition that "the human soul is mortal or that it is one for all humans" (DH 1440).

The teaching of the Protestant Reformers differs little materially from that which is taught commonly during the Middle Ages. Nobody questioned the common doctrine of the composition and unity of body and soul, though the latter was understood, at least implicitly, in a Platonic and spiritualist sense, more centred on individual salvation after death (immortality of the soul) than on eschatological consummation at the end of time (see Resurrection). Yet under the influence of Nominalism and Augustinianism, a subtle change began to take place. It was no longer generally accepted that the existence and nature of the soul could be arrived at by rational deduction, whether in Aristotelian or Platonic terms. Peter Aureolus (1280-1322) and William of Ockham (1280-1349) thought that there was no reason to attribute the immaterial acts of knowing and willing to an immaterial form or soul, the existence of which can only be known by faith. Likewise Cardinal Cajetan (1468-1534) was convinced that the immortality of the soul is as unknown to humans as the mystery of the Blessed Trinity or the Incarnation of the Word, and opposed Lateran V's suggestion that philosophers should teach students how to justify this doctrine rationally (cf. Martin, 1995). Perhaps on account of a certain pessimism present in the later Middle Ages the doctrine of the survival of the soul after death and its final reintegration at resurrection was coming strictly under the sway of the theological virtues of faith and hope, and no longer under reason. It is interesting to add that Ockham, though accepting by faith the existence of an immaterial and incorruptible form in man, was not prepared to say that this form informs matter directly. He endorsed the opinion according to which there are in the human being several substantial forms, at least a form of corporeity and the intellectual soul, or perhaps three distinct forms. It would seem therefore that the loosening of the bond between soul and body and the gradual reappearance of dualism, was accompanied by an ever growing difficulty of reflecting on the ontological reality of the soul in purely rational terms. Immortality is no longer considered a "natural" quality of the human soul, but rather a gift of the divine grace. In other words, both dualism and fideism seemed to move at the same pace. Understandably, philosophers began turn their attention to the human soul in terms of tangible human subjectivity, overlooking its ontological aspects.

VI. The Human Soul and Subjectivity in Modern Philosophy

It may be said that the existence and subsistence of the human soul becomes, after the existence of God, the principal, unquestioned "article of faith" of recent centuries. Yet its existence and properties are explained and reflected upon not in metaphysical terms. The soul is not looked upon as a reality that founds immaterial actions, but mainly as an element localising human thought, consciousness and subjectivity, in the context of a prevailing scepticism induced by Nominalism and reinforced by fideism (cf. Stock, 1999).

1. Radical Dualism and the Supremacy of the Soul. The humanism of the Renaissance went beyond putting the soul at the centre of things; the centre, rather, is human subjectivity, as in the writings of Marcellus Ficinus (1433-1499). Intent on countering the inroads of sceptical empiricism,  Descartes (1596-1650) attempted to establish a kind of "clear and distinct idea," an incontrovertible point of certitude that goes beyond all doubt, in observing that human thinking and existence always go together. "I can be sure of nothing else but that I think," he would say; and as a result, cogito, ergo sum, "I think, therefore I am" (Principia Philosophiae I, 10). We are able to doubt everything, he says, except the fact that we exist and think. As a result, for Descartes, the soul itself is considered as a thinking subjectivity, the self-thinking self. In this process, he observes, thought is distinct from both the body and sensation; the soul in fact operates on the basis of "innate" ideas and relates to the body only accidentally. Body and soul are thus separate substances, the res extensa and the res cogitans respectively, and there is no true substantial union between them. "I have a body to which I am closely united," he says. "Nonetheless since on the one hand I have a clear and distinct idea of myself, according to which I am only a thing that thinks and not something extensive, it is certain that I, that is, my soul, by which I am what I am, is completely and truly distinct from my body" (Meditationes de Prima Philosophia,  VI). Though Descartes insists that the union between body and soul is very close, his vision is undoubtedly dualistic. The human being consists of two complete though mutually linked substances: he is an animal controlled by a spiritual soul. The soul exercises its influence on the vital spirits of the pineal gland, where it is located, and in return it receives images and sensations from the corporal organs.

Malebranche (1638-1715) takes up the basic thrust of Descartes' arguments, affirming however that the soul does not exercise any real influence over the body, or vice versa. Rather, the desires of the soul provide God with the "occasion" of producing the required reaction in the body. Spinoza (1632-1677) radicalises Descartes' doctrine in a pantheistic fashion by affirming that body and soul are two modes of the one Substance, coinciding respectively with extension and thought. In other words there is a strict psycho-physical parallelism between "body" and "soul." Both terms designate the same reality: the soul is the "idea of the body"; the body is the object of the mental idea that constitutes it. Instead of "soul", Spinoza speaks preferentially of "mind" (Lat. mens). The understanding of the relationship between body and soul is expressed by Leibniz (1646-1716) with the aid of his theory of monads: simple, indivisible, incorruptible, closed, incommunicable substances out of which everything is composed. For Leibniz body and soul relate to one another in a purely exterior fashion, working side by side synchronically, in that the Creator establishes a primordial harmony between them. Similar ways of speaking of the soul are to be found in authors such as Goethe, Hölderlin and Moses Mendelssohn (cf. Pieper, 1968).

Understandably the problematic side of the equivalence Descartes established between soul and consciousness would come to the fore with the passing of time. In fact Immanuel Kant (1724-1804) censured Descartes, Mendelssohn and Leibniz for uncritically affirming continuity between the psychological and metaphysical spheres. It is not legitimate, he said, to deduce the existence of a soul that is substantial, simple, incorruptible, personal, spiritual and immortal from the subjective experience of thinking (cf. Critique of Pure Reason, II, II, 1). The soul may be said to exist, Kant says, but only as an idea or "postulate of practical reason." That is to say, were there no such thing as the human soul, it would be impossible to develop a consistent religious and ethical system. He considers the doctrine of final resurrection, however, as merely symbolic or even superfluous.

2. The Soul and the Self as a Product of Matter. The English philosopher David Hume (1711-1776) developed the scepticism motif, referred to above, in open opposition to Descartes. He argued that human selfhood is but a "bundle of perceptions," a kind of theatre in which different apprehensions make their appearance and which bring us to come to consciousness in knowing. In other words consciousness derives from the presence of objects perceived, and not from a pre-existent spiritual soul. Hume does not as such deny the soul (or better, the mind) as a spiritual substance, but affirms simply that we have no way of proving its existence. In a similar fashion William James (1842-1910), passsing from Hume's agnosticism to an explicit materialism, concluded that the soul did not exist at all but was merely a collection of psychic phenomena. Bertrand Russell (1872-1970) would graphically describe the spirit as "matter in gaseous state."

A distinct phenomenon facilitating the decline of the Cartesian understanding of the soul developed in the area of experimental psychology at the end of the 19th and beginning of the 20th centuries. The psychologies of Freud, Jung and Adler, took no interest in "the soul" as such. All three, however, in spite of significant variants, developed psychologies "of the deep," and came to appreciate that the mind does not operate only at a conscious level, as Descartes and others as much as said by identifying the soul with conscious thought. The mind has a life of its own, much of which is "unconscious" or "subconscious." Though the notion of "depth" had not been lost on classical thought —think of Augustine's cor (or to the corresponding biblical term), and of Bonaventure's apex - however, Freud's symbolic equivalent of the "soul" remains entirely self-referential, unrelated to God or religion; psychoanalysis and psychotherapy take the place of spiritual life (mysticism) and redemption. Against Descartes depth psychologies also "rediscovered" that the human mind is deeply influenced and determined by somatic influences of all kinds, a notion to which Aquinas, with his doctrine of the soul as the only substantial form of the human body, gave full expression.

Some authors of the phenomenological school such as Edmund Husserl (1859-1938) attempted to go beyond mere descriptive psychology, and revindicated a renewed ontology of the human spirit. However, experimental psychology, by the fact that it insisted on the psychosomatic unity of the human being, tended for the most part to deny its spirituality, immortality and free will. Something of a kind is to be found in Marxist thought. In linking realism with materialism, Marxists considered the "soul" as a mere epiphenomenon or product of matter, and denied its existence as a spiritual substance. Friedrich Engels (1820-1895) once said: "What is original, spirit or nature? According as one responds to this question, philosophers divide in two great schools. Those who affirm the originality of spirit over nature admit in one way or another the creation of the world... Those for whom nature is original belong to the different schools of materialism" (L. Feuerbach und der Ausgang des klassischen deutsche Philosophie, 1886). For materialists the "soul" as such does exist. It is a conventional term used to express the unstable and alienating epiphenomenon of individual human life. Psychical and conscious life are considered the highest product of matter (of the physical world). They are the function of that particularly complex form of matter called the "human brain."


Modern science has given special attention, directly and indirectly, to the human soul in two directions: in dealing with the evolutionist hypothesis and in relation to the Mind-Body problem developed by philosophers and neurologists during the 20th century.

1. Evolutionism and Hominization. In 1859 Charles Darwin (1809-1882) published his famous work The Origin of the Species by means of Natural Selection. Though many of his findings have since been thoroughly revised and even reversed, the original thesis he put forward, that humans are direct descendants of the higher primates, was destined to become extremely popular. Besides, on the basis of evolutionary and genetic continuity with lower animals, and therefore with the biological, chemical and physical world, it began to be argued that man could have evolved ultimately from even lower forms of life. Though many scientists and philosophers accepted Darwin's position and followed through on it, theologians and Christian philosophers for the most part expressed reservations. On the basis of the contrary teaching of Scripture, they perceived that evolutionism seriously questioned the unity and transcendental character of man. Given however that humans probably share 99,5% of their evolutionary history and 95% of their genetic patrimony with higher primates it is understandable that scientists and philosophers would continue attempting to come up with other possible explanations of the evolutionist phenomenon. Several Christian thinkers (cf. Gardeil, 1893; Leroy, 1891; Zahm, 1896) and others during the 19th and early 20th centuries formulated what was known as the "transformist" hypothesis, which explained that the human body proceeds, ultimately, from non-human parents, yet the soul is created directly by God. Becoming a human being (what is generally called "hominization") may be considered therefore as a process that is staged in time. This hypothesis simplifies things a lot, in that the body is taken to be the reserve of science, while the soul is put aside for the study of theologians and philosophers.

Though Church authorities reacted at first against these positions, theological reflection continued. In the Encyclical Humani generis (1950) Pope Pius XII made it clear that the evolutionist hypothesis —specifically in respect of the origin of the human body from already existing living matter— is not a priori contrary to Catholic faith (cf. DH 3897). This teaching was confirmed and made more precise by John Paul II (cf. Message to the Pontifical Academy of Sciences, October 22, 1996; cf. also John Paul II, General Audience, May 27, 1998, n. 5), who refers to evolution as a "theory," and no longer as an "hypothesis." However it should be noted that the evolutionist theory of staged hominization, even in mitigated form, is still problematic from a philosophical standpoint, for it can easily be seen to mark a return to the plurimorphist explanations common throughout the Middle Ages, or even to outright dualism. Should the human body already possess a complete "form" of its own (vegetative, sensitive) before the creation and infusion of the soul, then the latter can hardly be considered as the unica forma corporis (see above, V.2), and the difficulties typical of the dualistic interactionist theories of Descartes and others will tend to arise anew. Although we do not know how a link took place between the higher primates and Homo sapiens, in order to avoid dualistic extrinsecism we should join the adjective "human" to the body only insofar as it is united to the soul. According to this Church teaching, the "human body" begins to exist only when the human soul is created. It should be added of course that science may well be in a position to establish that the evolutionary history and genetic pattern of humans coincide more or less with those of higher primates. Yet such a morphological or genetic continuity is not enough to postulate a direct causal link between non-human progenitors and Homo sapiens, unless we endorse a reductionistic view of all properly human behaviour. Strictly speaking, such a missing link is not open to scientific research, but rather to philosophical (and not only theological) enquiry.

2. The Mind-Body Relationship. The growth of experimental psychology during the 20th century spawned a wide variety of schools and scientific approaches to the question the soul and human specificity. Of particular importance was the "methodological behaviourism" of B.F. Skinner (The Analysis of Behavior, New York 1969) and the "logical behaviourism" of Gilbert Ryle (The Concept of Mind, London 1949). In simple terms, "behaviourists" consider humans as highly complex machines whose laws and workings can be deduced by scientific observation of their external behaviour. Platonic or Cartesian dualisms are strictly excluded.

Criticisms of behaviourism did not delay in coming (cf. Bunge, 1980; Rorty, 1980). Yet the perennial dilemma of the relationship between body and soul comes to the fore again in terms of the relationship between mind (which takes the place of "soul" or "spirit") and body. Against empiricists, materialists and behaviourists, the existence of the mind is unequivocally affirmed. Yet it is still asked: what is the relationship between the self, subjectivity, the mind, on the one hand, and the biological, chemical and physical organism usually termed the brain, on the other? A wide variety of explanations drawing on neurobiology, the cognitive sciences, information theory, computer science, linguistics and sociology, have been suggested (cf. Seifert, 1989; Pinkas, 1995; Maldamé, 1998; Searle, 1998): the theory of identity (Feigl) with the associated question of artificial intelligence, that of emergentism (Bunge), and that of interactive dualism (Popper, Eccles).

Helmuth Feigl in his work The "Mental" and the "Physical" (1958), taking issue with the behaviourist position, insists on the real existence of the human mind. The human being is more than an automated mechanism driven by stimulus and response. Human behaviour, at least in part, is directed by a self-conscious self. Hence the "self" cannot be identified with behaviour as such, but with the interior principle of behaviour. The mind however, according to Feigl, is identified purely and simply with the brain. He takes this approach because of what he calls "the principle of economy" according to which there is no need to multiply unnecessarily the causes of any phenomenon. If therefore all human processes, events and mental states (mental teleology, behavioural intentionalism, cognition, willing choice) can be explained adequately on the basis of the workings of the brain, there is no need to postulate the existence of a spiritual principle of life. Feigl takes it that this is the case: if cerebral processes could be mapped in sufficient detail on a screen as it were, human action and development could be suitably predicted. Leaving aside for the moment the fact that many philosophers and neurologists refuse to identify the mind (or soul) with the brain, what Crick (1994) called the "binding problem" still remains, and can be stated as follows: what keeps such structures in their place first of all, and, even more, where did their form or structure originate?

The "emergentist materialism" of Mario Bunge (1980) rendered Feigl's reductionist view obsolete (cf. Del Re, 1997). Matter is all that exists, according to Bunge, but within reality matter expresses itself in qualitatively distinct levels of being. Each level supposes the anterior one, yet surpasses it ontologically. Common experience does not permit us to understand everything in purely physical terms. He accepts that the mind is the brain, but adds that the human brain differs qualitatively and not only quantitatively from any other known material object. The human being must thus be distinguished both from the biosphere, and from his nearest genetic relative, the chimpanzee. The principal property of Bunge's emergentist materialism is what he calls "plasticity," that is the aptitude of the brain to programme and organise itself. The theory of emergentism attempts to find a better theory to fit the facts than does the reductionist identity theory. Similar attempts may be found in recent years in authors such as Changeux (1983, 1989), Dennett (1995), Edelman (1987/8) and Boncinelli (1999). However, insofar as they generally begin with a monistic view of reality from which higher levels of life are seen to spontaneously emerge, it is difficult to shake off the impression that such levels are merely quantitative improvements of the lower ones. Little space is left for either human intentionality or transcendence (Maldamé, 1998).

Mind-body dualism continues to be popular among philosophers and scientists. Authors such as Karl Popper (1977) and John Eccles (1989) are probably still the best known representatives (cf. Popper and Eccles 1977; Eccles 1989). Karl Popper approaches the problem of the mind-body relationship from the perspective of his theory of the "three worlds". Apart from the world of physical entities (World 1) and of mental phenomena such as subjective experiences, consciousness, etc. (World 2), there is also a world comprising the products of the mind: history, scientific theories, social institutions, works of art, etc. (World 3). The existence of World 1 cannot be doubted. Yet Popper holds that real existence must be attributed to the other two as well in that their empirical effects can be experienced and checked in that they really act on the inferior worlds. It is evident that the products of the mind (World 3) are what most decisively influence physical reality (World 1). As a result, it must be said that there exist real beings that are incorporeal. But World 3 exercises its influence on World 1 only through the workings of the mind, World 2, which according to Popper is a real entity that surpasses the purely physical and corporal, even though it is in need of them in order to act. In other words, the mind is distinct from the brain, even though it interacts closely with it. Thus it is the self that possesses the brain, and not the other way around. Popper in fact quite openly adopts the explanation popularised by Plato: the self (the soul) is like a tiller to a boat, or like a pianist to a piano. The position of Popper has been accepted by other renowned philosophers and neurophysicists such as John Eccles, A. Green, R. Penrose and R.W. Sperry. Though confirming the need to retain the presence of a non-material principle of action in the human being, this position tends however to return to the problematic positions of Plato and Descartes.

VIII. The Human Soul between Theology and Science

After this survey it would seem that only two main alternatives remain as regards the existence and substantiality of the human soul: dualism and monism. Either the human soul exists as a separate (or at least separable) substance that controls the body from without (Plato, Descartes, Popper), in principle a "spiritual" substance produced by the divinity and capable of meaningful survival after death. Or it designates a configuring form totally bound up with the unitary psychosomatic structure of humans, which simply dissolves at death. Understandably, the Christian doctrine of creation and eschatological fulfilment cannot accept either as a unique solution. Many attempts have been made by theologians throughout the 20th century to express anew what is intended traditionally by the human soul, especially in the context of the challenges presented by the sciences. We shall briefly examine Karl Rahner's (1904-1984) understanding of "hominization," and the Lutheran Wolfhart Pannenberg's (born 1928) explanation of human identity in the context of eschatological salvation. Both suggest what might be termed "actualistic" understandings of the human soul (cf. G. Greshake, G. Lohfink, 1975).

Karl Rahner (1961) explains that the origin of life can be attributed entirely to God in the realm of primary causality (creation), and entirely to generation as regards secondary causality (that is evolution). God can thus be considered as the real and transcendental basis of the evolutionary process in the world. That is to say, God works at the very heart of creation in and through secondary causes, without ever replacing or interrupting them. Divine causality in other words acts from within a finite causality, elevating and empowering it to go beyond its own potentialities. God's action therefore is what brings about the creature's self-transcendence, what scientists might call "emergentism." Applying this principle to humans, Rahner says that both God and pre-hominoids are fully the cause of the entire human being. God's power brings out the full potential of the prehominoid state, constituting humans as persons, thus going beyond the biological chain of reproduction. As a result the uniqueness, irreplaceability and spirituality of the human person is rooted in the creating and empowering action of God. "Emergentism" leads both to "personhood" and "grace."

A number of 20th century Reformed authors, such as Thielicke, Althaus, Cullmann, Barth and Pannenberg, commonly deny the "natural" immortality of the human soul, and as a result, its substantiality as a metaphysical co-principle of the human being. Some Catholic theologians have tended to move in the same direction (for example, Greshake, Lohfink, Ruiz de la Peña). The theology of the first Reformers, however, had not traditionally denied the immortality and substantiality of the human soul, but quite the contrary, although they emphasized that it was a tenet of faith, and, as such, unattainable by reason alone. This change of perspective is mainly due to the preference contemporary authors have for both pure Biblical exegesis (Scripture speaks openly of final resurrection and not so much of the immortality of the soul), and "de-Hellenization" of historical Christianity, thus calling the existence of the soul into question. However, it seems that the main difficulty Reformed theologians encounter with the doctrine of the immortality and substantiality of the human soul lies elsewhere. In modern philosophy the soul had come to be understood mainly in terms of subjectivity and of a human aspiration to the Absolute (for Lessing the soul is an "an infinite striving," for Fichte it is the combination of knowledge and deed, for Nietzsche, the will to power). In such a context, an immortal soul is perceived as a source of autonomous human actions and thus a threat to the traditional Luteran doctrine of justification by faith alone, by grace alone, as if the human being could offer to God something that had not first been received from Him (cf. A. Ahlbrecht, Tod und Unsterblichkeit in der evangelischen Theologie der Gegenwart [Paderborn: Verlag Bonifacius-Druckerei, 1955], pp. 112-120; O'Callaghan, 1997). According to Karl Barth, if God alone is immortal (cf. 1Tm 6:16), then the human soul cannot be such.

Leaving aside the variety of questions the denial of the immortality of the soul involves from a theological standpoint, some Reformed theologians in recent times have wished to recuperate the notion of soul (cf. Hermann, 1997). Others, such as the Lutheran theologian Wolfhart Pannenberg, have put forward what might be termed an "actualist" or dynamic understanding of what has traditionally be called the human soul (cf. Pannenberg, 1998). According to the latter the "separated soul" after death should not be considered as a subsistent being as such; rather the individual human being would as it were be "retained" in the mind of God during the intermediate period between death and final resurrection. At the consummation of time the person would receive definitive fullness and immortality as a kind of new creation.

Pannenberg takes it that modern science has demonstrated that the "soul" is not an object as such, but rather an aspect of the dynamism of life and of human behaviour. Hence it would make no sense to speak of the immortality "of" the soul. Besides, he notes that Christian hope is founded on the notion of novelty, and not on that of stability and continuity. Pannenberg admits however that Christian theology has historically accepted the notion of the subsistence and survival of the soul as a vital principle, for reasons not necessarily bound up with an uncritical assimilation of Platonism. The doctrine in fact is closely related to salvation and resurrection, and was put forward in order to ensure that human identity between the earthly and risen state is maintained. The so-called "immortality of the soul" is what made it possible for resurrection to take place; the "soul" as forma corporis was seen to retain the scheme, project, genetic code or éidos (that is, the image) of the individual human being. Pannenberg considers, however, that a subsistent immortal soul capable of surviving death and ensuring final resurrection should in principle be in a position to undergo new human experiences. However this would actually disqualify its very reason of being, for new experiences (those involved for example in purgatorial purification and the intercession of the saints) would provide the soul with a distinct identity, as if the human person was present in plenitude. As an alternative, Pannenberg suggests that human identity "during" the intermediate period between death and resurrection would be guaranteed better if such identity were retained or "codified" in God himself, because it is only "in Him" that our lives and histories can be made immortal.


A proper application of Aquinas's hylomorphism may well be in a position to overcome the drawbacks of both monistic and dualistic understandings of the relationship between body and soul (cf. Borghi, 1992). Thomas Aquinas strenuously opposed the teaching of Averroes which suggested that the so-called "possible" (or receptive) intellect was unique, and common to all human beings. If the "possible intellect" were single and separate, then it would be divine and eternal, and as a result the senses and imagination would be only accidentally involved in intellection. He likewise opposed Avicenna and others who spoke of the oneness of the "agent intellect" (though admitting the plurality of possible intellects). Were it so, the intellectual operations would not belong to the one and same individual subject, since the latter would be a mere instrument of someone else, says Thomas Aquinas, adding: hic homo intelligit —it is "this" man who knows, understands, etc. (cf. Summa Theologiae, I, q. 76, a. 1). If a "unique" intellect is assumed for all, the human soul is nothing but a fragment of deity which is in act in every individual; likewise, the senses and immagination could play only a merely accidental role in human knowledge (cf. Summa Contra Gentiles, book II, ch. 76; Summa Theologiae, I, q. 79, aa. 4-5). The position maintained by Rahner and Pannenberg is not far from what Aquinas here intends to criticize. They both suggest what might be termed an "actualistic" view of the human soul: God is considered to be the one who enlivens each human being at the level of formal (or quasi-formal) causality. Significant drawbacks, however, are present in both approaches.

Rahner's hominization theory on the face of things offers a reasonably coherent solution to the dilemma posed by evolution. But it does so at a cost. First, there is no good reason why the divine action that brings finite beings to transcend themselves should be reserved to individuals that are genetically identifiable as humans. Put in another way, the difference between human and non-human beings can only be quantitative, not qualitative; spirit would constitute simply a more evolved state of matter. Second, if divine efficient causality is what brings about the self-transcendence of finite beings, then the actions attributed to the beings in question may remain unrelated to their respective natures. This would involve a confusion between "instrumental" and "second" causality (see Autonomy). Thomas Aquinas teaches that in the order of creation, and specifically in that of the spirituality of the human soul: "Nulla actio convenit alicui rei, nisi per aliquod principium formaliter ei inhaerens —no action can be performed by a subject without any principle that is inherent in that same subject" (Summa Theologiae, I, q. 79, a. 4). And elsewhere: "non dicimus quod calor calefacit, sed calidum —we do not say that heat makes something hot, but that a certain hot body makes something else hot" (ibidem, q. 75, a. 2). That is, immaterial actions of whatever kind (knowing, loving, acting freely) can be meaningfully attributed to humans only if they derive from a proper immaterial substance, that is, the human soul. Otherwise they can only be attributed to some distinct immaterial reality, an external, common "agent intellect," for instance, or the Divinity itself. It would be more correct to say that the direct action of God on man at the level of primary causality involves the creation of the human soul, the unique form that makes it possible for humans to will, to know, to be open to God, etc.

Likewise Pannenberg's position as regards the immortality and substantiality of the human soul does not give sufficient consistency to created reality as such. In a Christian context he is correct in considering God as the only one capable of granting immortality or permanence to the human being in its concrete lived identity. However, not unlike Rahner, he is mistaken in seeking out human identity (and thus immortality) only in the concrete history of the person, and not to the human subject of that history. Humans, before having a personal history and developing a concrete identity, were already human with a spiritual dignity written into their very being. In fact the doctrine of the immortality of the soul is not only meant to guarantee the identity of the singular history of each human being, but rather to ensure the metaphysical identity of their being human. Pannenberg's opposition between (eschatological) novelty and (Platonic) stability is problematic for the same reason. In the absence of a metaphysically stable subject, no novelty would be possible or meaningful, because any novelty would presuppose a discontinuity in respect of what was previously present. "Novelty" must be a novelty of something. The subject of such "novelty" in Pannenberg —certainly for as long as the intermediate period between death and resurrection lasts— could only be God himself, the objective Spirit, of which the individual human being (the "subjective spirit") would be a simple derivation or manifestation.

A document of the Roman Catholic Church issued from Congregation for the Doctrine of Faith provides a brief but helpful summary of what the Christian theology should maintain about the human soul, framed within an eschatological context: "The Church affirms that a spiritual element survives and subsists after death, an element endowed with consciousness and will, so that the "human self" subsists. To designate this element, the Church uses the word 'soul,' the accepted term in the usage of Scripture and Tradition. Although not unaware that this term has various meanings in the Bible, the Church thinks that there is no valid reason for rejecting it; moreover, she considers that the use of some word as a vehicle is absolutely indispensable in order to support the faith of Christians" (Letter on Certain Questions concerning Eschatology, May 17, 1979). Both serious scientific endeavour and religious and philosophical reflection over the centuries, have led to the reality of the human soul as the living, spiritual, "informing" centre of each human being. Historically speaking it can be argued that whereas science insists primarily on the inseparability of body and soul, that is, on the "psychosomatic" unity of the human person, religion leans towards the distinctness of the soul from the body, and thus, including the possibility of favouring a certain dualism between the two. Christian doctrine, however, on the basis of the oneness of the creating act of God, teaches that the spiritual soul is the only form of the human composite, yet, in the light of the doctrine of final resurrection, it allows also for the possibility of a temporary survival of the soul separated from the body. Besides, Christian doctrine understands the immortal dignity of each human being in terms in direct creation of human souls by God, and on this basis unequivocally teaches the priority of the specifically spiritual co-principle of the human beings (cf. Schönborn, 1984).

Documents of the Catholic Church related to the subject: 

Abbreviations and complete titles of the documents

Synod I of Toledo, DH 190; Leo I, Quam laudabiliter, DH 285; Anastasius II, Bonum atque iucundum, DH 360; DH 403; Synod of Braga, DH 456; Council of Vienne, DH 902; Lateran Council V, DH 1440; DH 2135; Gaudium et spes, 14; CDF, Letter on Certain Questions Concerning Eschatology, 17.5.1979, EV 6, 1528-1549; ITC, Contemporary Questions on Eschatology, 16.11.1991, EV 13, 448-572; John Paul II, General Audience, 27.5.1998.


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