Diana Mertz Hsieh (email@example.com)
Aristotle (Phil 5081, Robinson)
29 October 2002
In the three books of De Anima, Aristotle ranges over a diverse array of philosophical and scientific topics, such as the nature of life, self-movement, the senses, perception, imagination, thought, and the relation between mind and body. As a result, this work may seem to be a strange collection of only marginally related philosophical and biological topics given our modern sensibilities. Nonetheless it is united by Aristotle’s basic concern for the nature and functioning of life in all its diverse forms. This sweeping inquiry, when combined with Aristotle’s well-established philosophical methods, offers modern readers significant insight into contemporary debates in the philosophy of mind.
Aristotle’s Three Methods of Inquiry
Perhaps owing to the relative brevity of the work, De Anima clearly highlights three of Aristotle’s common methods of philosophizing, namely his focus on basic biological facts, his integration of ideas with the basic principles of his philosophical system, and his analyses of his predecessors. By briefly examining each of these methods before turning to the substance of Aristotle’s reasoning about the soul, we may make more sense of Aristotle’s arguments and conclusions.
First and foremost, Aristotle consistently appeals to his considerable knowledge of biology to support his arguments. For example, in Book I Aristotle argues that his predecessors “fail to take into consideration all kinds of soul” because not all living things engage in the activities so designated as those of the soul, such as movement and breathing (DE 410b16-411a2). Similarly, his discussions of the functions of the senses all rely upon his biological understanding of how the sense organs function (DE 418a26-424a15). The errors and gaps in Aristotle’s scientific understanding of living organisms are not as significant here as we might initially suspect, as Aristotle’s concern with the nature of all living organisms by itself is sufficient for his connection between questions about the nature of mind and questions about the nature of life. For Aristotle, perceiving, eating, moving, growing, thinking, and imagining are all activities of living things, whether plant, animal, or human (DE 413a23-25). Thus Aristotle emphasizes “the continuity, rather than the differences, between process in plants and processes in humans” (Sorabji 165). This deeply biological approach to the human mind is a fruitful one, but unfortunately at variance with much contemporary debate about the mind.
The second principle of method running throughout Aristotle’s works – but particularly evident in De Anima – is Aristotle’s consistent integration of his investigations with the basic principles of his philosophical system. This practice is clearly seen in the opening paragraphs of Book I, Chapter 1 of De Anima. In the first paragraph Aristotle invites us to make “a completely fresh start” by asking, “What is soul?” (DE 412a1-5). Then, with breathtaking rapidity, he formulates an answer to that question using his ideas of substance, form, matter, actuality, and potentiality – all in three short paragraphs (DE 412a6-26). The form/matter distinction proves particularly useful to Aristotle, as it allows him to describe the living organism as an inseparable “complex” of soul qua form and body qua matter (DE 414a16-17). Additionally, Aristotle also integrates his account of soul with his theory of the four causes in arguing that the soul is “the source of movement” (the efficient cause), “the end” (the final cause), and “the essence” (the formal cause) of the “whole living body” (DE 415b8-11; Hammond xxii). The physical body is thus simply the material cause of the organism. One significant consequence of this integrative approach is that Aristotle has the conceptual framework to offer an account of the mind that is neither materialism nor dualism.
Aristotle’s third common method of philosophizing found is the review of the strengths and weaknesses of the views of his predecessors in order to “profit by whatever is sound in their suggestions and avoid their errors” (DE 403b22-3). Hence in Book I Aristotle examines and rejects the ideas that soul is “what moves (or is capable of moving) itself,” that it is “a kind of harmony … of contraries”, and that it is “the subtlest and most incorporeal of all kinds of body” (DE 406a1; DE 407b30; DE 409b21-2). These analyses often prove particularly valuable in discerning what Aristotle’s views actually are by showing what they cannot possibly be.
By using these three philosophical methods throughout De Anima – by focusing on basic biological facts, by integrating with the basic principles of his system, and by analyzing his predecessors – Aristotle’s basic conclusions gain an empirical strength and coherence often lacking in contemporary discussions of philosophy of mind.
The Basic Account of the Soul
In Book II, Chapter 1 of De Anima, we find Aristotle’s “sketch or outline of the nature of soul” (DE 413a10). By this point in the text, Aristotle has already reviewed and discarded the common views of his predecessors, so Aristotle now seeks to “formulate the most general possible account” of soul (DE 412a5).
But precisely what does Aristotle mean by “soul”? What exactly are we investigating? In the essay “Body and Soul in Aristotle,” Richard Sorabji explains the possibility of confusion over the concept “soul” thusly:
The word ‘soul’ may sound archaic to some modern ears, and people may be tempted to substitute ‘mind’. But then they are likely to confine the functions of the soul to what we call mental acts, and this will take them away from Aristotle’s conception of the soul (Sorabji 164).
Instead, as Sorabji persuasively argues, we ought to recognize Aristotle’s “conception of soul [as] co-extensive with life, that is, with all life” (Sorabji 165). Indeed, the only way for us to make sense of Aristotle’s talk of the “nutritive soul” of plants and the “sensitive soul” of animals is to understand the soul as applicable to all life rather than simply mental life (DA 434a22-30). This emphasis on life itself is a direct outgrowth of Aristotle’s first method of focusing on basic biological facts.
Aristotle begins his account of the soul with a brief review of his theory of form and matter. Summarizing his arguments from Metaphysics, Aristotle notes that substance can mean form, matter, or the combination of form and matter in an individual particular (M 1043a13-28; DE 412a6-9). Matter is associated with potentiality, for (as Apostle notes) it “underlies … change and can take on various … forms” (DE 412a9-10, Apostle 95). On the other hand, form is actuality because (as Aquinas notes) it is “that in virtue of which there is … in actuality an individual thing” (DE 412a9-10; Aquinas 412A6-11). Or, as Aristotle says in Metaphysics, “matter exists in a potential state, just because it may attain to its form; and when it exists actually, then it is in its form” (M 1050a15-16).
Aristotle then differentiates between two types of actuality, “one as e.g. knowledge, the other as e.g. reflecting” (DE 412a10-11). According to commentators on De Anima, this distinction separates unexercised capacities from exercised capacities (Apostle 97n14; Aquinas 412A6-11; Kosman 145; Wedin 15). So Avogadro’s Number is knowledge (an unexercised capacity) in a person’s mind until that person reflects upon it (exercises the capacity) in order to compare the molecular weight of nitrogen to oxygen. Thus we might think of knowledge-type actuality as a passive power and reflecting-type actuality as the active exercise of that power (Apostle 99n34).
Having reviewed these basic principles of his system, Aristotle then uses his second method of systematic integration in order to arrive at his “sketch or outline of the nature of soul” (DE 413a10). Aristotle argues that the living organism is a substance in the sense of a “composite” of soul qua form and body qua matter (DE 412a17-22). Thus soul is the “actuality” of “a natural body having life potentially within it” (DE 412a20-22). But what sort of actuality is soul? It is a passive power like knowledge or an active exercise of that power like reflection? Aristotle reasons that “the soul is an actuality like knowledge” on the grounds that “both sleeping and waking presuppose the existence of a soul” where sleeping corresponds to “knowledge possessed but not employed” and waking to “reflecting” (DE 412a 22-26). Thus Aristotle describes the soul as “an actuality of the first kind” where “first” means “prior in time and existence” because any power must be prior to the exercise of that power (DE 412a26-27; Apostle 97n16). For Aristotle, the active exercise of these capacities cannot be the essence of soul, for that would preclude the dormant plant, the sleeping animal, and the unthinking man from possessing a soul (Wedin 15).
Thus, we have good reason to adhere to the common interpretation of Aristotle’s conception of the soul as designating certain types of capacities. One such commentator, Michael Wedin, argues that Aristotle regards the soul as “a complex of … actual capacities” (Wedin 15). Richard Sorabji similarly argues that soul for Aristotle is “a set of capacities, such the capacity for nutrition, the capacity of sense-perception, and the capacity for thought, … related to each other in intimate ways so as to form a unity” (Sorabji 163). Such an interpretation makes good sense of Aristotle’s analogy of soul to sight where he observes, “if the eye were an animal – sight would [be] its soul” (DE 412b18-19). Sight is the capacity of the eye for seeing, just as soul is the capacity of the organism for the actions that characterize life.
To say a soul is really just a set of certain capacities is far from a complete account of the nature of life or mind, but it is a promising start.
Neither Materialism Nor Dualism
Given this theory of the soul, including its implications for the nature of the mind, Aristotle’s views cannot be assimilated into the seemingly strict either-or choice between materialism and dualism1 that often characterizes contemporary debates about philosophy of mind (Searle 204). Aristotle cannot be a dualist because he clearly rejects the idea of the soul as something ontologically distinct from the body. But neither can Aristotle be a materialist, for such an interpretation would make his basic contrast between soul as the form of the living organism and body as the matter incoherent. Aristotle, it seems, is offering us a third and new choice in the philosophy of mind, despite the propensity to interpret him as either a kind of materialist or a kind of dualist (Sorabji 163).2
Examining the possibility of a dualist interpretation of Aristotle in greater detail, we quickly find that we are far too easily misled by language. To speak of “souls” and “bodies” often sounds as if we are speaking of soul as a substance on par with body and capable of independent existence, as we find in Plato and Descartes (Plato 64c; Descartes 25). But Aristotle’s conception of the soul as the form of the living organism absolutely denies the possibility of it as a substance in that sense. The whole living organism is the primary substance for Aristotle; that organism is not an amalgam of the primary substance of soul and the primary substance of body.3
Further reason to reject a dualistic interpretation of Aristotle is found in his analysis of the problems associated with the view of the soul as self-moving in Book I, Chapter 4. There, Aristotle notes that “we speak of the soul as being pained or pleased, being bold or fearful, being angry, perceiving, [and] thinking” (DE 408b1-2). These descriptions of movement seem to indicate “that the soul is moved” and thereby lend support to the idea of the soul as that which moves itself (DE 408b2-3). While admitting that such “movement is originated by the soul,” Aristotle admonishes us to be careful about our use of language in writing, “it is doubtless better to avoid saying that it is the soul that pities or learns or thinks, and rather to say that it is the man who does this with his soul” (DE 408b5-14). This argument is a direct rejection of the language associated with dualism; the whole argument is only coherent if we take Aristotle to be advocating the view that the soul is a set of capacities rather than a separate substance. Thus, once again we have been helped along by Aristotle’s method of analyzing the views of his predecessors.
However, we might wonder whether Aristotle abandons his commitment to the inextricable unity of matter and form where human thought is concerned (Sorabji 170). Although Aristotle may consider the possibility of thought independent of body, his conclusions concerning the relationship between sensation, imagination, and thinking preclude accepting it. For Aristotle, “the soul never thinks without an image” and all imagination is “movement resulting from an actual exercise of a power of sense” (DE 431a17; DE 429a2). As a result, all thinking “requires a body as a condition of its existence” (DE 403a7-10). Mind cannot exist independent of body.4
Given these considerations, the temptation to interpret Aristotle as a dualist disappears. But in order to determine whether Aristotle’s views fall outside of the choice between dualism and materialism, we must obviously still consider whether Aristotle’s views preclude materialism as well. This time, Aristotle’s own concern for proper philosophical methodology proves invaluable.
In Chapter 1 of Book 1, in the discussion of the proper approach to the subject of soul, Aristotle seems to be endorsing a materialist conception of mental states in speaking favorably of a physicist’s understanding of anger as “the boiling of the blood or warm substance surrounding the heart” (DE 403a31-32). But any attempted materialist interpretation of this passage disintegrates as we continue reading (Sorabji 175). Aristotle’s argument is that such a purely physical account of anger is incomplete. Similarly, a purely psychological explanation of anger as “the appetite for returning pain for pain” is also incomplete (DE 403a30-31). The complete explanation of anger (and other affections of the soul) consists in the combination of both the “material conditions” and the “form or account” (DE 403b1-2; DE 403b 7-8). A materialist conception of the mind, in contrast, is seeking only the material conditions.
Interestingly enough, Aristotle’s requirement that there be both material and formal conditions in an explanation, as illustrated through his house analogy, precludes not only identity theory, but also reductionism. Aristotle argues that understanding the nature of a house is directly analogous to understanding the nature of anger. We would be remiss if we described a house as “stones, bricks, and timbers” without any reference to its end and form as “a shelter against destruction by wind, rain, and heat” – or vice versa (DE 403b4-6). A proper description, Aristotle argues, “would say that it was that form in that material with that purpose or end” (DE 403b7). Identity theory is thus rejected as making the mistake of thinking that the “stones, bricks, and timbers” are identical with “a shelter against destruction by wind, rain, and heat.” But such an identity relation cannot withstand scrutiny, as the material compounds of a house will both predate and postdate the house itself (Sorabji 175). Similarly, to advocate reductionism would be to make the mistake of asserting that “a shelter against destruction by wind, rain, and heat” is nothing but “stones, bricks, and timbers.” But we cannot reduce formal causes to material causes within the Aristotelian system.
Thus although Aristotle’s biological focus may seem to push us towards a materialist interpretation of the mind, it is an untenable interpretation. Aristotle is neither a dualist nor a materialist, but rather something else entirely.
A Radically Different Approach
The particulars of Aristotle’s theory of mind are unlikely to withstand intense scrutiny. After all, the form/matter distinction essential to his account is difficult (if not impossible) to integrate with our modern scientific understanding of the world in terms of the atomic theory. But we should not relegate Aristotle’s views to the dustbin of philosophical history yet, for Aristotle’s focus upon the organism as a whole as the proper object of study may well be a fruitful approach to the question of the nature of and relationship between mind and body. This approach itself is contrary to both the dualist and the materialist approach to the mind.
Speaking somewhat loosely, we might say that the dualist takes the existence of minds as obvious and then proceeds to wonder how we might possibly account for bodies. Thus in Meditations on First Philosophy, Descartes argues for the indubitable existence of minds in the Second Meditation, but only gets around to arguing for the existence of bodies in the Sixth Meditation (Descartes 24-25, 71, 80). Materialism takes the reverse approach by regarding the existence of bodies as obvious and then wondering how we might possibly account for the existence of minds. So in Philosophy of Mind, Jaegwon Kim formulates the basic mind-body problem as that of “accounting for the place of mind in a world that is essentially physical” (Kim 9). On either of these approaches to the mind-body problem, accounting for the unity of and causal relations between mind and body becomes a Herculean task because the organism has already been severed into two competing aspects, one self-evident, the other mysterious and seemingly inexplicable.
In contrast, Aristotle’s basic approach offers us a way out of this dilemma. As we have said, Aristotle regards the whole organism, the unity of soul and body that is a living being, as the proper starting point of the inquiry. He does not, as the dualist and materialist do, presuppose the existence of one aspect of the organism and then wonder fruitlessly about how to account for the existence of and relations with other aspect. Rather, from Aristotle’s deeply biological perspective, every organism is a “unit” such that any divisions between soul and body or between parts of the soul are only “convenient abstraction[s]” (Hammond xxi). As a result, explaining the relationship between mind and body is no more difficult than explaining the unity of features found in any individual particular entity.
In fact, Aristotle is quite explicit about the problems we can create for ourselves in speaking of the unity of things in Metaphysics Book 8, Chapter 6. There, Aristotle explains that understanding unity is impossible if we start off by wondering how all the features of an entity are glued together (M 1045a7-20). He writes,
Clearly, then, if people proceed thus in their usual manner of definition and speech, they cannot explain and solve the difficulty [of the unity of features of an entity]. But if, as we say, one element is matter and another is form, and one is potentially and the other actually, the question will no longer be thought a difficulty. For this difficulty is the same as would arise if 'round bronze' were the definition of 'cloak'; for this word would be a sign of the definitory formula, so that the question is, what is the cause of the unity of 'round' and 'bronze'? The difficulty disappears, because the one is matter, the other form (M 1045a21-30).
Thus we resolve the apparently intractable problem of unity by adopting a different approach to the subject, by designating one aspect the matter and the other aspect the form. To resolve the problem in this way, however, still requires us to make use of Aristotle’s questionable form/matter distinction, but we need not follow Aristotle down that route. We may think of the mind as a particular type of action of the organism as a whole or as an emergent property in the Searlean sense (Searle 111-112). The point is simply that we ought not make the unity and causality of mind and body a harder problem than it really is. We can, as Aristotle does, simply accept that unity as a brute fact, perhaps requiring an explanation in terms of efficient cause but no more:
Therefore it is like asking what in general is the cause of unity and of a thing's being one; for each thing is a unity, and the potential and the actual are somehow one. Therefore there is no other cause here unless there is something which caused the movement from potency into actuality.
In other words, the problem of mind-body unity and causality is only a terrible problem if we first bifurcate the human organism into mind and body before even beginning the investigation in the way that both dualism and materialism do.
Of course, we are still left with a great many questions about philosophy of mind. Aristotle’s particular answers are unsatisfactory because they rely upon outdated science. But Aristotle’s basic approach to the subject of life and mind, driven as it is by his philosophical methodology, offers us hope that reasonable answers may be found – if we are careful to ask questions in a sensible way.
Apostle, Hippocrates. 1981. Aristotle’s On The Soul. Grinnell, Iowa: The Peripatetic Press.
Aquinas, Thomas. 1999. A Commentary on Aristotle’s De Anima. Translated by Robert Pasnau. New Haven: Yale UP.
Aristotle. De Anima. Translated by J.A. Smith.
Aristotle. Metaphysics. Translated by W.D. Ross.
Charlton, William. 1993. “Aristotle’s Definition of Soul.” In Aristotle’s De Anima in Focus. Edited by Michael Durant. New York: Routledge.
Descartes, René. 1988. Descartes: Selected Philosophical Writings. Translated by John Cottingham, Robert Stoothoff, and Dugald Murdoch. New York: Cambridge UP.
Green, Christopher. 1997. “The Thoroughly Modern Aristotle: Was he really a functionalist?” Presented at Aristotle and Contemporary Science, Thessaloniki, Greece in September 1997. Available at .
Hammond, William. 1902. Aristotle’s Psychology. New York: MacMillian.
Kim, Jaegwon. 1998. Philosophy of Mind. Boulder: Westview Press.
Losman, Aryeh. 1994. “Aristotle’s Prime Mover” in Self-Motion: From Aristotle to Newton. Edited by Mary Louise Gill and James Lennox. Princeton: Princeton UP.
Plato. Phaedo. Translated by Hugh Tredennick.
Searle, John. 1992. The Rediscovery of the Mind. Cambridge: The MIT Press.
Sorabji, Richard. 1993. “Body and Soul in Aristotle.” In Aristotle’s De Anima in Focus. Edited by Michael Durant. New York: Routledge.
Wedin, Michael. 1988. Mind and Imagination in Aristotle. New Haven: Yale UP.