Lesson 1: The Importance of the Study of the Soul: An Historical Introduction

The human soul, St. Thomas Aquinas writes, exists on the "confines of the spiritual and corporeal" (Summa Theologiae [hereafter ST], I, 77, 2). The human person is thus a microcosm of the whole universe, a little world, in whom the perfections of both the spiritual and the material orders coincide. St. Thomas adopts Aristotle's account of human beings as composites of soul and body, wherein soul is related to body as form to matter. This is the so-called hylomorphic theory of human nature. Composed of matter and form, human beings are akin to all other natural substances. But, since the highest capacity of the human soul is the intellect, which is an immaterial power, human beings are peculiar examples of matter-form composition. Nowhere else do we find an immaterial power united to a body.

St. Thomas's position eludes categorization in terms of the fundamental modern and contemporary alternatives of dualism and materialism. Nor does it help to depict hylomorphism as a compromise or middle position between dualism and materialism. The latter are closer to one another than either is to Aquinas. Descartes' emphatic rejection in his Meditations of the body as constitutive of whom we are as human beings provides a classic statement of dualism and sets the terms of debate over human nature well into this century.1 What are the motives behind his project, the defining project for modern philosophy?

In the opening of his Meditations, Descartes laments the lack of certitude in all that he has learned. Except for some of the proofs of mathematics, Descartes' education has given him nothing more than probable knowledge, most of which rests upon the opinions he has inherited from tradition and his elders. Even were the knowledge handed on to him without error, he would still be in a position of doubt; for, he has accepted it on trust. If he is ever to arrive at absolutely certain knowledge, he will have to raze to the ground all the opinions that he has inherited from others and build his knowledge upon a more secure foundation. He puts doubt in the service of certitude, as he sets out to establish indubitable knowledge by rejecting whatever admits of any doubt. Thus he dismisses the senses which are sometimes deceptive. The most radical proposal is that, because it is possible that some immensely powerful, malevolent being could deceive him about even such seemingly certain truths as those taught in mathematics, he also sets these aside. It is important to note here that Descartes' doubt applies solely to thought not to action; he admits that it would be absurd to try to live in accord with such doubt. But if one wants to provide an unshakable foundation for all of knowledge, the method is the appropriate means. Where then do we arrive at a certain basis for knowledge? In the very hypothesis of a deceptive evil genius. For, if he is deceiving me it follows that I am being deceived, and, if I am being deceived, I am thinking and thus I must exist. Having reached this first certainty, Descartes asks: But what am I? "A man, of course. But what is a man? Might I not say 'rational animal'? No, because then I would have to inquire what 'animal' and 'rational' mean. And thus from one question I would slide into many more difficult ones." Rejecting as too complex the Aristotelian definition of man, he proceeds to inquire whether he can affirm of himself anything bodily.

But what about being nourished or moving about? Since I now do not have a body, these are surely nothing but fictions. What about sensing? Surely this too does not take place without a body.... What about thinking? Here I make my discovery: thought exists; it alone cannot be separated from me. I am; I exist--this is certain. But for how long? For as long as I am thinking... I am therefore precisely nothing but a thinking thing. (Meditations, II)

The remainder of the meditations is familiar. Descartes offers an argument for the existence of an infinitely perfect being, thus eliminating the hypothesis of the evil genius and providing an avenue back to the external world. If God is infinitely perfect, he is not a deceiver and our trust in the deliverances of the senses is reasonable. It turns out not only that there is an external world but that we are somehow united to a body. But, like all physical things, the body is merely extended matter in motion. We can have clear and distinct, that is, certain, ideas about the physical world only in so far as we construe nature in mathematical terms.

As much as Descartes' thought breaks with the thought of Aristotle and Aquinas, it retains certain themes and assumptions. Descartes thinks that the basic truths about human nature and the world, even God, are accessible to human understanding. Indeed, he is quite, perhaps inordinately, optimistic about the clarity of the knowledge we can achieve in these areas. He also refers to the intellect as a light of nature. But the crucial break has been made. There is no natural goal or telos to human nature and the place of human beings as parts of the whole is rendered inscrutable. The relationship of mind and body is especially bewitching. The novelist Walker Percy speaks of the "dread chasm that has rent the soul of Western man ever since the famous philosopher Descartes ripped body lose from mind and turned the very soul into a ghost that haunts its own house."2 The entire physical world is raw material upon which we exercise our control. Thus does the argument of the Meditations provide a basis for Descartes' mathematical physics, whose goal is to render us "masters and possessors of nature."

The dualism espoused by Descartes is often contrasted with materialism, which refuses to countenance a mind or intellect distinct from the operations of bodily organs or physiological processes. In this, dualism and materialism are indeed polar opposites. But a proponent of materialism like Hobbes is equally unsympathetic to the Aristotelian conception of the soul as animating principle of the body. On this issue, it makes little difference whether one follows Cartesian dualism or one of the many variants of materialism in modernity. Hobbes writes,

For seeing life is but a motion of limbs, the beginning whereof is in some principal part within, why may we not say that all automata (engines that move themselves by springs and wheels as does a watch) have an artificial life? For what is the heart, but a spring, and the nerves, but so many strings; and the joints, but so many wheels, giving motion to the whole body, such as was intended by the artificer?

Human beings are merely complicated machines.3 Reason is simply a complicated device of calculation; as he puts it, the activity of reason is coextensive with the operations of addition, subtraction, multiplication, and division (Leviathan, chapter 5). The consequences of Hobbes' banishing of the soul as animating, organizing, and directing principle of the body are immediate and striking. Freedom and coercion are indistinguishable, and reason is but a slave of the passions (Leviathan, chapter 6). There is no ultimate end or natural goal to human life; there is thus no shared common good in light of which ethical reflection and political life might be conducted. We are isolated individuals, threatened at every moment by the potential attacks of every other individual. Our only end is the "restless desire for power after power." But even this fails to provide security and we are haunted by the fear of violent death. Since reason can discern no goods or ends shared in common by all human beings, Hobbes turns our attention away from properly human goods to the sub-rational, to the sub-human, to animal necessity, to the fear of violent death. The only way out of the natural state of war is by the establishment of a commonwealth, to whose leader we cede our natural right to do whatever we deem necessary to enhancing our prospects of survival. Much of modern philosophy involves an attempt to circumvent the seemingly endless debates over which goods are properly human and how a regime should be constituted so as to embody these goods. Even John Locke, who is often regarded as having a much milder account of the state of nature, still grounds human government in the animal necessity of hunger, allied to the human capacity of labor.

In response to Hobbes' determinism and materialism, to his degrading depiction of the human condition, thinkers from Rousseau through Kant and up to the existentialists have sought to defend the dignity and freedom of human beings. Rousseau is the earliest and most powerful critic of Hobbes. Rousseau counters that Hobbes simply imposes upon the state of nature all the vices that accrue to human beings only after they have entered civilization. To arrive at the state of nature is to reach the childhood of mankind, a condition of humanity prior to the invention of language, reason, and imagination. By stripping away the adult capacities, whose invention accompanies the complexities of civilization, we can see that prior to civilization human beings would have had neither the motives nor the forethought to be combative in the way that Hobbes depicts them. "The same cause that prevents savages from using their reason... prevents them from abusing their faculties." In this period before human beings develop self-consciousness, they lack the "egocentrism" of later man. Their lack of reason and their limited conception of the future make it impossible for them to be burdened by a multitude of passions. Thus, the concern for self-preservation is hardly "prejudicial" to that of others. Rousseau compares us with our first parents in this way: "So much more profitable to these [primitive men] is the ignorance of vice than the knowledge of virtue is to those [civilized men]" (Discourse on the Origin of Inequality, Pt. I, Hackett, p. 869). Rousseau provides us with a much more harmonious and pleasant picture of our first parents, but he saddles us with other problems. Most of the capacities that we celebrate as properly human--such as reason, language, and will--are, for Rousseau, precisely the instruments of our corruption and wickedness, of our alienation from nature, ourselves, and one another. In that sense, the comparison of the state of nature to the childhood of mankind is not apt. The transition from our original state to our present one is not the result of a natural development, the actualization of proper potencies present within our original state; instead, the transition is the result of a violent, revolutionary rupture. Indeed, we are so far removed from the state of nature that to call the pre-civilized beings and civilized beings by the name "man" is highly questionable. It's almost as if one species replaced another.

As we shall see more clearly in later lectures, most efforts to overcome the reduction of human life to animal necessity (fear of violent death in Hobbes or labor in Locke) return us to some form of dualism, where, in order to protect human autonomy, the body is denigrated as merely biological. Not surprisingly, dualism fails to alleviate the problems we have inherited from Descartes: of the place of human beings in the natural world and of whether there are any limits on the exercise of human mastery over nature--the goal, you may recall, of Descartes' scientific enterprise. The vanishing of man, the evanescent self, that so-called post-modern philosophers have proclaimed as our fate--this can be seen as the logical term of the modern eschewal of soul.

Since the time of these classical modern debates over the state of nature and the human condition, philosophical investigations of human nature have been in steady decline. There are a number of reasons for the demise of the philosophy of human nature. There is, first, the splitting up of the perspectives on human life into various disciplines: sociology, biology, economics, and ethics and religion. The suggestion that out of these disciplines could emerge a unified and comprehensive conception of human nature is dismissed as quixotic. There is, second, an influential scientific project that would consign the study of human nature to the biological and chemical sciences and reduce human thought and volition to physiological processes. Third, there is the philosophical reaction, especially prominent in certain strains of existentialism, against scientific reductionism; this reaction denies the relevance of natural science to understanding the human world of freedom. Science is said to study natures; it tells us what something is and is not capable of studying a person, a "who" not a "what." Finally, there is the project of modern political liberalism that eschews any determinate conception of human nature as an impediment to democratic politics; instead of nature, the basis of politics is consensus and freedom. These are important obstacles to the recovery of Aquinas's account of human nature, but the seeds of all of them can be found in the doctrines concerning nature and the human condition in the early modern period.

Reading Assignments

Descartes, Meditations, especially meditations I-II; Hobbes, Leviathan, introduction, chapters I- 6, 11, and 13-14.

Writing Assignments

1. Compare the approaches to human nature and human knowledge in Descartes and Hobbes.

2. How does Descartes reach the truth that he is a thinking thing? Raise one or two objections to his approach to knowledge and/or human nature?

Suggested Reading 

Pierre Manent, The City of Man (Princeton University Press, 1998).


1. See Meditations, II, transl. Donald Cress, Hackett Pub., 1993.

2. Love in the Ruins, p. 191.

3. Leviathan, introduction, ed. E. Curley, Hackett Pub., 1994.


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