Consciousness

Abstract: Speculation about the nature, scope, and structure of human consciousness has consistently made use of a vocabulary of terms for mind, soul, and spirit. The mind is always the seat of reason, intellect, and cognition. The soul always signifies life force. Spirit is usually a divine endowment added to an ensouled body and connecting the individual to god. Religion situates these ideas of mind and soul within its own doctrines of human creation, of obligations to God, and of possible salvation. These ideas have flowed from four principal sources: Plato’s separate immortal substance, Aristotle’s matter-form functionalism, Epicurus’ atomic materialism, and the three Christian doctrines of the Holy Spirit’s gift, the second life, and bodily resurrection. ⸙

Sources of Consciousness

Speculation about what makes humans conscious, in contrast to mere animal sentience, has consistently made use of a vocabulary of terms for mind, soul, and spirit. The mind (nous, mens) is always the seat of reason, intellect, and cognitive operations. The soul (psychē, anima) always signifies life force. The spirit (pneuma, spiritus) is (usually) a divine endowment added to an ensouled body, connecting the individual to god. Sometimes spirit signifies the presence of a fifth essence, a rarified, very fine matter. Various religions situate their pictures of human consciousness within their own distinctive doctrines of human creation, obligations to God, and possible salvation. Theories of consciousness in the West have flowed from (at least) four principal sources: Plato’s separate immortal substance, Aristotle’s matter-form functionalism, Epicurus’ atomic materialism, and the set of unique Christian doctrines of the Holy Spirit’s gift, the second life, and bodily resurrection.

Perhaps the most significant watershed in the history of modern speculation about consciousness occurs in the second of Rene Descartes’ Meditations. In two closely conjoined passages the meditator sums up his new, forward-looking affirmation of the concept of mind and his prior, backward-looking rejection of previous false beliefs. “What then did I formerly think I was? As to the nature of this soul, either I did not think about this or else I imagined it to be something tenuous, like a wind or fire or ether, which permeated my more solid parts …. [But] I am then in the strict sense only a thing that thinks; that is, I am a mind or intelligence or intellect or reason — words whose meaning I have been ignorant of until now” (1985: 17). In the earlier statement the meditator repudiates his previous belief that the soul is an analogue of a natural element. But why did he formerly believe just this about the soul? The very words that he uses to capture his previous views are image-based ideas from the previous two thousand years about the interior, hidden dimension of human nature. The earliest well-attested speculations occur in the Hebrew Bible and Homer, both dating from the same period (mid-700s B.C.E.).

Ancient Concepts

In ancient Hebrew, there are three main words — nepesh, ruach, and leb — for an inner aspect of human being. Each of these words has nuances, the meanings of which depend on whether the word is the subject or object of an action, whether it is predicated of an animal or a human or God, and with which verbs of action it is linked. In Hebrew leb is both the thoracic cage that holds the heart and the organ that “holds” thoughts and memories. The ruach is the breath that fills the lungs and carries the life force through the whole body. The nepesh is the desire manifest in an animal being the life force of which is instilled by God. The human being is a living thing (hayyim) composed of flesh (basar) or soft tissue and bones and sinews. Like an animal, a human has or is nepesh, a vital force responsible for self-moved action. Its key properties are breath and blood flow, which can increase or decrease during sleep or anger. Although Yahweh has instilled ruach in all animals, including humans, ruach has distinctive functions and effects in humans because the human heart confers additional features. The human heart is an inner fleshy organ like any other animal’s heart, but in rational humans the heart is also the seat of memory and intellect. Through the loss of nepesh in their animal being, humans also lose both ruach and leb, and thus the Hebrew human soul is mortal, the dead being consigned to the dusty shadows.

Homer employs various soul-related words. One group of terms is comprised of psychē, thymos, menos, and nous, all of them psychical functions dependent on an animal body, which is its host, though the “seat” or internal site of these functions is indefinite and underdetermined. Although these terms are unfocused and overlapping, they refer to some inner, hidden power which endows the soul with complex properties. It is psychē that uniquely differentiates human beings from other living animate beings by means of vital attributes such as self-moved action, desire for what is absent, and the ability to take counsel within oneself. In Homer and the Hebrew Bible these aspects of consciousness are articulated like the muscles and tissues depicted on archaic and geometric vases and bas-reliefs. They are pieces connected by means of joints, which are functional components that hinge around a more solid frame. Obvious emotional states, such as anger, sadness, and lust, were considered little more than the external manifestations of an inner, invisible, but concrete life force. Soul was believed to be present only when these affects were strongly displayed. Hence psychē and nepesh are absent or at least dormant when an animal or a human is quiet and immobile, sleeping, or unconscious. Like the Hebrew nepesh, perishability of the Homeric psychē means that humans are bound by death, except for the few lucky heroes who live again like gods.

The centuries from the Homeric age to the classical Greek age are transitional in the development of ideas about the nature, source, and functions of the soul. The conjecture that the human soul is immortal was deeply interlinked with exotic foreign ideas about ecstatic foresight, out-of-body projection, and magical practices. In some of Plato’s dialogues Socrates seems to be trying to reconcile the common traditional view of psychē with this radically new doctrine of the soul as an immortal and immaterial element in human nature. In the middle and late Platonic dialogues the soul becomes a unifying and unitary entity which has various powers and can be conceptually divided into forms or kinds. Plato’s soul is incorporeal, immortal, and divine, just like the eternal, immutable Forms.

In the Phaedrus Plato presents one of his great “myths,” using the archetypal imagery to arrive at truths of reason about the nature and powers of soul. He declares that his story applies to “soul in all its forms,” including the Form (eidos) of the human soul itself. The principal image of human being is a winged chariot: the chariot, its driver, and two horses, one of them noble and one of them base. Like all other animals, the human has (a) a chariot (the body), dragged along, inanimate, not self-moving; (b) a noble horse, which aspires to higher ideals; (c) a base horse, which craves desirable things; and (d) in humans alone, a driver (reason), which presides over the whole ensemble.

The well-known doctrine of the so-called tripartition, or three-part soul, occurs in Books Four and Ten of the Republic. Some traces of this doctrine also appear in the Timaeus and the Laws. The long and intricate argument in the Republic is devoted to the dialectical discovery of three distinct aspects of the human psyche: (a) logos or logistikon = the reasoning or that-which-reasons; (b) thumos or thumoeides = the spirited or that-which-inspires; and (c) epithumos or epithumētikon = the desiring or that-which-desires. The rational power of the whole human has to take account of the needs and desires made known to it through the non-rational power. Nevertheless, the rational power of the soul (nous) is itself an autonomous whole insofar as it accords with the cosmic plan of an order of beings. In this order that-which-reasons is not a power or function of some thing but an agent or entity the basic nature of which is expressed through human beings’ rational governance of their beliefs and actions, especially actions directed toward moral goods.

Plato’s greatest student, Aristotle, disagreed vehemently with his teacher’s view that the soul is an independent, immaterial, and immortal thing. Plato’s “mystical” description of the powers of the soul failed to explain why only certain kinds of living things had souls. Aristotle did not accept the concept of soul as a separate and separable substance. Rather, he maintained that the soul is the form of an animal being as a whole. Its special form (eidos) imparts or informs life-force to the body’s matter (hulē). Aristotle’s account (logos) of soul (psychē) makes excellent use of several conceptual templates: substance and attribute, matter and form, and explanatory factors (aitia). He characterizes psychē as the first actuality (entelecheia) of a natural body capable of sustaining life — that is, an organism composed of organs. Psychē expresses the living thing’s defining essence (ousia), its cause (aition), its principle (archē) and its goal or end-state (telos).

In common English phrase the psychē is “the life and soul” of an organism, engaged in natural activities to satisfy its bodily needs. Life is not a precondition of activity. Rather, to be alive is to be engaged in outwardly-directed activities that constitute one’s nature (phusis). But Aristotle’s matter-form template comes unstuck in his treatment of mind (nous), an argument that violates his strict functionalist account. In De Anima (III.5) he claims that nous has no bodily organ, so that the cognitive faculty or power (to nōetikon) is not only logically distinct but actually separable from the body and the rest of the psychē. Despite his materialist, functionalist inclinations he seems committed to the view that some aspect of the human being survives bodily death. By the next century Epicurus (and his later Latin expositor, Lucretius) had no qualms about embracing human mortality. For Epicurus, the soul is nothing more than highly refined “gas” diffused through the body and dispersed at death. The gods do not care anyway.

The most important change in early accounts of soul, mind, and spirit comes from Christianity, in efforts by St. Paul to accommodate Greek philosophical concepts to Christian eschatology and soteriology. In the New Testament psychē indicates something distinctive about human being as the carrier of life force. Psychē sets off identity criteria for what gives or keeps life in human nature, both in this world and in the next one. Often psychē is contrasted to pneuma since psychē marks out the individual human as such, the one who can be moved inwardly through reflection, the one who can be influenced by others, and the one who can suffer and undergo passions and affections.

Paul adopts the Greek term pneuma (Latin spiritus) to mean the divine gift of breath (as in Genesis “God’s breath,” which confers life), but in an entirely new sense. On the New Testament view not every human has “spirit” from birth or by nature. Rather, spirit is conferred by baptism, by accepting Christ as one’s savior. In virtue of having spirit, each individual will achieve redemption in heaven and resurrection at the Second Coming. Those without spirit are damned in both body and soul. They are not redeemed and are not resurrected. Paul also held the mysterious doctrine that in their earthly existence humans lived in an ensouled body and that after death the redeemed “live” in a spiritual body.

The Middle Ages and Renaissance

In the fifth century Augustine achieved an exceptional, comprehensive synthesis of Christian and Platonic doctrines of human nature. Plato’s mystical thought provided him with the vision of God and the soul, and Christ’s message with the path to that vision. Augustine offered an ingenious interpretation of Paul’s teaching about the soul’s taking upon itself a glorious, spiritual body after the Final Resurrection. In Genesis the human is created with an animal body made from organic parts, where the soul is not the whole human but his better part. As Paul stated, the soul is the inner human and the body the outer human.

Augustine read anew the enigmatic passage in 1 Corinthians 15, in which Paul writes about the first Adam made into an ensouled (psychikos) being and the last Adam made into a spiritual (pneumatikos) being. According to Augustine’s “double-life” thesis, after the body’s death in the first life it is a second life, granted by the Holy Spirit through God’s breath, that makes possible humans’ final post-resurrection status. There are thus two senses of death: the first death is the separation of soul from body in its earthly demise, to which all created animate things are subject; the second death is the separation of inbreathed spirit from the person in spiritual death, an event to which only the wicked and sinful are subject. In humans alone the ensouled and inspirited “parts” cohere in one nature.

In virtue of a human’s having or being a rational soul, God breathes in a spirit which the human can either accept or reject. In accepting, the human becomes a new being. In rejecting, the human becomes like a beast. In sum, human beings have a double nature, both a double life and a double death, such that every human exists in some sense as the first Adam. That is, our common humanity is our death-bound earthly existence. But we also have our own individual life, which began at conception, the ensoulment of this particular animal being.

Aristotle’s works passed into the Eastern Roman Empire and, from about 800 C.E. onward, into the Islamic world, where they were avidly taken up by Arabic and Persian scholars. Alfārābī’s (c. 870‒950) account of the animal soul, the rational intellect, and his theory of knowledge are rather crude mixtures of Aristotelian and Neo-Platonic doctrines, organized around two registers: one to account for the ordered appearance of the world-whole and the other to account for the place of humans in that world order.

Avicenna (980‒1037) thought of the soul as one unitary and unified substance and posited one organic agency in the body through which it governed: not the brain but the heart. Avicenna thereby carried forward one of the main Stoic psycho-physical hypotheses about the reciprocal relation of animal body to its hegemonic soul and bequeathed the medical-physical model to Albert the Great and Thomas Aquinas. Averroes (1126‒1198) located the human intellect in the vast storehouse of the cosmic Agent Intellect and thus uniquely distinguished his theory of mind from that of his Islamic predecessors. In positing the Agent Intellect as an entirely separate and eternal substance, he guaranteed the incorruptible nature of the material intellect, but he retained its dispositional character, thereby integrating the rational faculty with the whole process of cognition along Aristotelian lines.

With Aquinas (1224‒1274) medieval scholastic philosophy reaches its apogee — the New Testament married with Aristotle. Aquinas’ formulaic definition of soul is “the first principle of life,” and much of his early efforts are focused on the meaning of the concept of life as the basis of actual living things. There are, he maintains, vital activities that normally have bodies and bodily parts among their principles. Some principles of life clearly are in bodies and hence have material “natures,” but these principles are not souls. Aquinas accounts for the fact that only some specifically organized bodies have the principle of life by employing the Aristotelian concept of substantial form. The soul as the form of living organized matter is itself immaterial, and the human soul is the highest stage of all souls connected to animate bodies. The only being that can subsist by itself is a substance and not an accident of some thing more basic. Hence the human soul must be both substantial and immaterial. The rational soul or mind as an immaterial form is not affected by the corruption of its host’s animate body. Since it is able to “grasp” eternal truths though knowledge, it too is outside time and is immortal. The human body exists in virtue of the soul, whereas the soul does not exist in virtue of the body with which it is joined. Aquinas’ analysis of intellectual operations goes far beyond his ancient master Aristotle and poses questions relevant to theories of mind today.

Concurrent with the great Christian-Aristotelian summations of the 1300s, Italian humanist writers found scholastic accounts of the soul to be irrelevant to the pressing problems about how an average Christian should lead a good life. In many writers of this period, including Dante, Petrarch, and Nicholas of Cusa, one finds the persistent plea for a renewal of the religious doctrine of grace: the idea that divine force alone is capable of remaking the naturally selfish character of humankind toward higher ethical and spiritual goals. Charles Trinkhaus (1970) argues that for these humanists, an individual’s life was seen as the triumph of his energy, irrational desires, and selfish achievements, but now understood as the fulfillment of a high status in the hierarchy of beings granted by divine creation.

The most far-reaching and profound influence on the philosophical speculations of the next generation was the rediscovery, translation, and dissemination of Plato’s works and the Neo-Platonic commentaries and expansions. Largely through the intense labors of Marsilio Ficino in the late 1400s, the complete Greek texts of Plato’s dialogues, Plotinus’ Enneads, and the Hermetic Corpus were recovered and translated into Latin. In his own magnum opus Ficino adopted an explicitly Platonic attitude toward the central issue of the nature of the human soul and also toward the character of philosophy itself as the disciplined pursuit of truth and wisdom. He agreed with Plato that the soul is related to God as the power of vision is to the sun’s light. Human beings, in their search for the truth, are directed toward the contemplation and reverence of God, their creator. Insofar as the human soul is God’s greatest creation, in attempting to understand the natural truths that God has instituted in this world, we attempt to understand our own soul. The human soul bears within it the image of God’s work, and this image manifests an eternal destiny — namely, its final end, its return to its source in the divine. Yet the reliance of Renaissance thinkers on an animate, dynamic model of reality crumbled when overthrown by the mechanical, materialist model in the seventeenth century.

The Modern Period

The extraordinary achievements of Rene Descartes (1596‒1650) in algebraic geometry and the mechanics of causal interaction are closely tied to his metaphysical speculation about the nature of bodies and minds. Descartes’ place in the history of the concept of mind is decisive. His Meditations (1641) provided a turning point in the good fortune of the career of mind at the expense of the place of soul in the scheme of things. In the Meditations and elsewhere he offered two accounts of the basic nature of human being: a physical theory about soul, couched in medical-organic terms, and a metaphysical theory about the mind in its relation to ensouled living bodies. His theory of soul was solidly situated in the prevailing medical model of organic functions controlled by neural “spirits,” whereas his metaphysical theory marked a radical overthrow of the standard Neo-Aristotelian account and a return to Augustine’s Platonism. Descartes’ metaphysical thesis on the true nature of mind held that the concept of mind, not the concept of soul, can be made the content of a clear and distinct intuition only through the chain of reasons, and this task means securing it firmly as a link in the progressive stages of the Meditations.

According to the order of reasons, the essence of mind is a thinking immaterial thing, and the essence of body is an extended material thing. But according to the order of beings, a human being is a mindful body, an interdependent fundamental substance, one that cannot be reduced without loss to its parts. Descartes’ isolation of the concept of mind permitted him to designate it as conscious: aware of itself as a thinking thing, entirely responsible for its own thoughts, an autonomous individual agent.

Once the concept of the soul was banished from serious philosophical discussion, a novel concept of the mind as a hidden machine or incorporeal automaton became the principal model under which various proposals as to its true nature were offered. Until the modern era in the West, meaning, value, and order were thought to be characteristics of the cosmic whole. The philosopher’s task was to figure out the place of humans in this scheme, and that task meant properly situating the concepts of soul and mind. Thinkers in the seventeenth century inaugurated a movement of radical displacement and disengagement from this older view of the human situation toward a modern view of the mind, and in so doing they relegated the concept of soul to religious exhortation and contemplation.

In reaction to this rationalist picture, empiricists such as Thomas Hobbes, John Locke, and David Hume proposed that the mind is “a portion of matter suitably disposed to think,” and this view has become the dominant one in contemporary debates. The modern search for the meaning of life, the realization of personal aspirations, and the abiding sense of moral responsibility are the products of a profound reorientation in our picture of the mind that began almost four hundred years ago. But these core features of modern individualism are not obviously compatible with a picture of the mind as a machine.

The Twentieth Century

The nature of mind and of consciousness occupies a prominent place in much current philosophy, in “pure” or theoretical psychology, and in computer science, especially artificial intelligence. As one witty fellow recently said, consciousness is to the 2000s what sexuality was to the 1960s: everyone knows that everyone has it, but now they all want to talk about it. The enormous boom in consciousness studies reflects an ever increasing excitement that computer-based models for pattern-recognition, computation, and problem-solving provide the best explanation for the workings of the human brain. The further philosophical claim that the mind is identical with the brain, or that mental states can be entirely explicated in terms of brain states, has given rise to a wide-ranging and heated debate. Many researchers in cognitive science believe that with current significant advances in neuro-scientific understanding of brain processes, the “hard question” of the true nature of mind is at last on the verge of an answer.

In any case, one must grant some cogency to a materialist account — that is, that a natural entity must be realized in some material way in order for it to have the property of consciousness. One wants to say that, whatever consciousness may be, an entity must have a brain in order to have consciousness. But how can consciousness depend on the brain in any way? The general thesis known as functionalism identifies consciousness with certain higher-order properties of the brain — namely, the more abstract causal properties that neuro-chemical states of the brain evince. Pain, for example, is a higher-order property of physical states that consists in having a certain pattern of causes and effects in order to mediate bodily injury and to avoid further pain.

But functional explanations have been open to some serious criticisms. It does not seem plausible to claim that possession of functional properties is sufficient to explain conscious awareness. Is it not conceivable that something can have the functional properties of chemical structures in the human brain and yet still not be conscious? Brain-states may have different causal roles from kidney or liver states, but the causal roles of all these organs are defined in terms of physical causes and effects. Therefore how can brain-states give rise to consciousness but kidney and liver states not? The problem is that the suggested properties are not specific enough to the brain, and they turn out to be the wrong kind of properties to determine consciousness.

Another attempt to address the problem about the right kind of properties has focused on computation. Since one of the principal dimensions of human consciousness is thinking, and since it is now thought that computation can best explain thought processes, perhaps computation in general underlies the intrinsic feature of consciousness. If humans can design computing machines and if consciousness is basically computation, then we will know, at least in outline, how to design a conscious machine. The adherents of this view want to construct a computational structure isomorphic with the human brain. To assert that the brain carries out computation is to claim that the brain literally performs mathematical operations. All these functional ascriptions attribute propositional content — to believe that, to desire that — to neuro-chemical processes and structures. This mental content is representeded in terms of internal symbols, so that the brain’s computations involve manipulation of these symbols. The human brain performs many of these computations, and the results are integrated into higher-level computations. The full claim, then, is that mental attributes, especially conscious states, can be identified with these computational processes. To have a mind is to instantiate a computer program.

Contemporary theorists of mind are almost uniformly dismissive of pre-twentieth-century accounts of mind and soul — except for Hume, perhaps. They often make appeals to “our ordinary intuitions” about the absurdity of substance dualist claims for an autonomous, usually immortal entity. Apart from the Epicureans, every theorist before the seventeenth century held that the soul outlives the death of its feeble, corrupt host. Thomas Hobbes’ unabashed materialist thesis, only feasible from an anti-Catholic perspective, revived this long-despised Hellenistic model and set the course for later explorers.

Yet moral thinkers take Plato’s theory of justice seriously. Others draw strength from Aristotle’s virtue ethics. Semiotician theorists find insights in medieval sign-theory. Without doubt, ancient accounts of the nature and functions of mind and soul suffered from serious deficiencies in their understanding of biological processes and the physical laws that govern mechanical interactions. But it is also eminently clear that neither Plato’s nor Aristotle’s nor Augustine’s account of the functions of mind depends on his model of biological and physical laws. Some apocalyptic thinkers have recently held out the promise of “a grand theory of everything,” one that will unite all known physical and psychical principles in an as yet unknown, undefined theory of something even more basic than the realms of mind and body. But that promise is surely the same kind of cosmic, overarching theory that the pre-Socratics hoped to achieve. It is little wonder, then, that some “new age” cosmologists wistfully want to rehabilitate Heraclitus.