The thoroughly modern Aristotle: Was he really a functionalist?

Christopher D. Green
York University

(1998) History of Psychology, 1, 8-20.

©1998 American Psychological Association.


In recent years a debate has developed over whether Aristotle's theory of the psuchê is properly characterized as having been "functionalist" in the sense that contemporary computational cognitive scientists claim to be adherents of that position. It is argued here that there are indeed some similarities between Aristotle's theory and that of contemporary functionalists, but that the differences between them make it misleading, at best, for functionalists to look to Aristotle for ancient support. In particular, it is argued that Aristotle would not have -- indeed, specifically did not -- support the claim, central to functionalism, that the mind can, in principle, be transported from one body to another simply by instantiating in the new body some set of organizational properties that were instantiated in the old.


Aristotle's theory of the psuchê was firmly rooted in his broader metaphysics, according to which all things are a combination of matter or hulê -- a sometimes shadowy, indefinite stuff with the potential to become most anything -- and form or morphê, which transforms matter into actual particular things. For instance, take some bronze, add the form of Pericles, and you have a statue of the great Athenian general. In this very simple case, "form" reduces to something very much like "shape." The meaning is much broader than this, however. Take some wood, for instance, add the form of a chair and you have a chair. Notice here that the "form" does not just mean the shape of a chair, but includes something of its functional characteristics as well. If you doubt this, imagine what would happen if you tried to add the "form" of a chair to some soap suds. Although form was clearly dominant in Aristotle's metaphysical thinking, matter was not by any means excluded utterly, as is sometimes implied. Matter was thought to be necessary, just not sufficient. Finally, consider a third example that brings us closer to the topic of this paper: take a human body, combine it with the "form" of life and you have a living human. In this case, the term "form" has to do almost entirely with function -- biological and psychological function, broadly speaking -- rather than shape. This particular form -- the one that turns a body into a living human -- was what Aristotle identified as the psuchê. To be fair, Aristotle did not believe that matter and form were "added" together, like so many things in a recipe. That aspect of these examples is purely pedagogical. Matter and form were tools of conceptual analysis; ways of getting at the definitions and explanations of things. This metaphysical framework, in which things are analyzed with respect to their form and matter, is called "hylomorphism."

Beyond these basic principles, however, almost every aspect of the interpretation of Aristotle's theory of the psuchê has generated controversy. Perhaps not surprisingly, the debate about what sort of theory Aristotle proposed has, at least over the last few decades, pretty well tracked the debate about what sort of a theory of mind is actually true. Because Aristotle's theory of the psuchê seems to have so much to do with "function," there has been a movement of late to assimilate his thought on the topic to contemporary computational functionalism.[1] In this paper I will critically review the leading interpretations of Aristotle's theory of the psuchê over the last 15 years, particularly those that claim that Aristotle was a functionalist with respect to the relation between body and psuchê. It is not the sole purpose of the paper to review, however. I will conclude by arguing that there is a general sense in which Aristotle might be considered to have been a distant relative of computational functionalists, but that it courts serious error and glaring anachronism to construe this in a way that puts Aristotle at the head of a line of thought that leads directly to that school of thought (viz., artificial intelligence-inspired cognitive science).

I should first examine some of the historically more significant options with respect to mind-body relations. Substance dualism is a position advanced by René Descartes in the 17th century. It holds that there are separate "substances" corresponding to the body (viz., matter) and the mind. Descartes called this mental substance the res cogitans. Descartes' position came under attack almost immediately. One of the most damaging criticisms was that if the mind is thought to cause the body to move, as Descartes believed, how can an immaterial mental substance cause the material substance of the body to do anything? Cause is a relation traditionally thought to hold only between two (or more) material entities. Partly as a result of this critique, people very soon began working to develop monist theories -- theories that posit only one kind of basic substance.

There are, obviously, two basic monist alternatives to Decartes: idealism, which posits that there is only mental substance (and that the body, and all other matter, is just a "projection," or somesuch, of the mind), and materialism, which posits that there is only material substance (and that the mind is somehow material, or doesn't exist at all). One very well-known sort of materialist theory of the mind (perhaps, better, an "anti-theory" of mind) is behaviorism. Behaviorism[2] holds that all mental talk (e.g., "Horatio wants to play baseball.") is really just talk about dispositions to behave in certain ways (e.g., "Given appropriate conditions, Horatio is likely to play baseball."). (Some behaviorists have argued that they are not materialists, but are "agnostic" about all metaphysical questions, in the manner of the logical positivists. For my present purposes they count as materialists in at least the minimal sense that they do not propose any non-material substances, and are inclined to treat the investigation of animal behavior in precisely the same way they would treat the behavior of non-living entities, such as planets, stars, and chemicals.)

Another materialist theory of mind, called physicalism, was also popular in the middle of the 20th century. One form of physicalism[3] popular in the 1950s held that anything one says about the mind can -- and should, if one wants to be scientific -- be redescribed as something about the activity of the brain. This is a strongly reductive form of materialism in that it claims that descriptions of mental events can be "reduced" to descriptions about neurological ones. Put another way, it claims that mental events and brain events are identical. For this reason this form of physicalism is sometimes called identity theory. One important implication of physicalism is that there is no such thing as consciousness, one of the primary attributes of Descartes' res cogitans (but see Place, 1956).

At about the same time as physicalism rose to prominence, it also became popular to claim that Aristotle's theory was of renewed importance precisely because it had been physicalist (though Aristotle, or course, never said so, specifically); he never seemed to say anything specifically about consciousness in De anima[4] or his other works (given some narrow interpretations of certain words such as aisthesis, "sensation" or "perception"). This is where our story about the modern interpretation of Aristotle begins.

Preliminary Sparring: Early Departures from the Physicalist Interpretation of Aristotle

In the early 1970s Jonathan Barnes (1971-2/1979) argued that the position in favor of Aristotle's having been a physicalist is erroneous (p. 32). Although he conceded that Aristotle never proposed a mental substance, as had Descartes, this did not commit him to physicalism, as had often been supposed (p. 34). Instead, Barnes claimed that Aristotle's theory is both non-substantialist (i.e., there is no mental substance) and non-physicalist (i.e., the psuchê is not completely redescribable in purely physical terms). The question, then for Barnes was to articulate a materialist interpretation of Aristotle (for if Aristotle were not a materialist, then there would be little point in discussing him seriously at all in the Zeitgeist of the early 1970s), without its being strictly physicalist. What Barnes ultimately argued was that Aristotle's theory holds that the psuchê is only an attribute or property of the matter of which the body is composed (in the sense that a functioning body can be said to have the property of being alive, but there is no particular material part that can be credited with giving life to the body). This position is sometimes called property dualism because, although it denies that there is a mental substance of the sort that Descartes proposed, it accepts that there may be mental properties (such as sensations and consciousness) that are somehow products of the (organization of the) matter of the body. Although Barnes denied believing Aristotle's theory to be correct, he said that it seems "at least as good a buy as anything else currently on the philosophical market. Philosophy of mind has for centuries been whirled between a Cartesian Charybdis and a scientific [i.e., physicalist] Scylla: Aristotle has the look of an Odysseus" (p. 41).[5]

Richard Sorabji (1974) argued against both the traditional physicalist view of Aristotle's theory and Barnes' "attribute theory," as well as against the view, which he said was still held by some, that Aristotle was a dualist of the Cartesian sort.[6] Instead, he claimed, "Aristotle's view is something sui generis. It is not to be identified with the positions of more recent philosophers" (p. 64). Sorabji was most impressed with Aristotle's comparison of the relation of the psuchê and the body to that holding between a house and the bricks that make it up. These cannot be identical, as physicalism argues, because, as Sorabji points out, the "bricks can outlast the house" (p. 78). Aristotle's view was not Cartesian either, however, because he believed the psuchê to be dependent for its existence on the body in a way Descartes did not (just like a house is dependent upon the bricks out of which it is made for its existence). Descartes believed the mind to be separable from the body, at least in principle. Aristotle states several times, however, that it is not.[7] Thus, Sorabji claims, "Aristotle improves on some present-day materialists, and on Descartes" (p. 78). Sorabji's ultimate interpretation of Aristotle's theory is difficult to paraphrase. He focuses on Aristotle's claim (in De motu animalium) that desire is just a heating of the blood around the heart. This heating is said to cause an expansion which, in turn, moves the body. Given this account, Sorabji argues, the fact "that desire should cause movement is no more (and no less) puzzling than that heating around the heart would cause expansion. But if desires lead to movement, then there is a sense in which the capacity for desire is responsible for movement" (p. 86). The capacity itself is not material, though it is dependent upon being composed of particular materials, just as the house is dependent on being made of certain materials in order to satisfy its function of being a shelter (consider, for instance, a house made of tissues). Since Aristotle says repeatedly that the psuchê is a set of functions or capacities (for nutrition, perception, etc.), Sorabji concludes that "this in turn means that the [psuchê] is responsible for movement" (p. 86).

Even though Sorabji claimed not to want to assimilate Aristotle's theory to any modern one, Howard M. Robinson (1978) argued that Sorabji's interpretation is very close to being "functionalist." Functionalism[8] is another (at least faintly) materialist view of mind that rose to ascendancy when physicalism and behaviorism began to fall out of favor in the 1960s and '70s. Recall that behaviorism says, roughly, that mental talk is "really" just talk about dispositions to behave in certain ways. Functionalism, to a first approximation, is the claim that this is not quite good enough. According to functionalists, the disposition to behave in a certain way must be accompanied by some sort of "internal state" for that disposition to be considered "psychological." A cone, for instance, when set upon its point might be said to have a "disposition" to fall over, but this does not warrant psychological descriptions of its behavior (e.g., that is wants to fall). Psychology, then, according to the functionalist is the study of the structure of these internal states, not just the identification of the dispositions for which they are responsible. In the 1960s, the structures of these internal states began to be explored by way of attempts to simulate them with computer programs of various kinds. The claim that the internal states must operate in the same way as computer programs is called computational functionalism and is the ground of much of the work done in artificial intelligence and contemporary cognitive science.[9]

One of the key implications of functionalism is that minds can, in principle, be "transported" into any physical system that can be arranged so as to preserve the functional relations. Thus, a human mind could, for instance, be instantiated in an electronic computer, provided the computer was programmed properly (the famous artificial intelligence researcher Marvin Minsky has even suggested this as a solution to the problem of human mortality!). This is known as the "transportability thesis" and figures crucially in the argument below.

Round 1: The First Functionalist Interpretation of Aristotle, and Its Rebuttal

Although Robinson criticized Sorabji for assimilating Aristotle's theory to contemporary functionalism despite Sorabji's denial that this is what he had attempted to do, Robinson's critique was not completely misplaced, for the arch-functionalist of the early 1970s, Hilary Putnam (1973), quipped that "what we [functionalists] are really interested in, as Aristotle saw, is form and not matter. What is our intellectual form? is the question, not what the matter is" (1973/1975, p. 302, original italics). Robinson (1978, p. 115) countered that Aristotle's theory is not functionalist because Aristotle is, after all, crucially concerned with the issue of "awareness" (or consciousness) of sensations, something that functionalism denies (or, at best, ignores). Notice that this view is exactly the opposite of that which led physicalists to show renewed interest in Aristotle's theory earlier in the century. Putnam's quip was developed by Martha Nussbaum (1978) into a full-blown interpretation of Aristotle's psychology. In an extended mock-dialogue between Aristotle and the ancient materialist, Democritus, she explicitly linked hylomorphism to functionalism, though she was silent on the question of whether computational structure might be even one of the kinds of "forms" Aristotle could have accepted.

In an article critical of Martha Nussbaum's (1978) functionalist interpretation of Aristotle, Robinson (1983) argued that Aristotle's theory is, contrary to most 20th century interpretations, dualistic after all. The primary piece of evidence he brings forward for this view is Aristotle's account of the active intellect (De anima, III.5), which is plainly said to be immaterial and separable from the body. Most 20th century interpreters of Aristotle have tended to ignore this fact, focusing instead on the possibility that the rest of Aristotle's theory of psychology might help extricate us from the dilemma in which Descartes is often blamed for having caught us. Robinson (p. 124) says that materialists have typically tried to dismiss the active intellect as the "unfortunate" effect of Aristotle's overall metaphysical position, and not a central part of his psychological theory in any case. According to Robinson (p. 127), however, the active intellect is essential to Aristotle's theory if he is to have an account of how people can think about abstract properties (such as being a triangle). Recognizing that most people would not be convinced by this argument, however, Robinson goes on to argue that there is other evidence that Aristotle's theory is dualistic through and through. In particular, he points to an analogy Aristotle offers in Book I of De anima -- that the psuchê bears the same relation to the body as does a sailor to his ship. By Robinson's light no plausible non-dualistic interpretation of this analogy is possible. Others, however, have dismissed the sailor analogy as a mere turn of phrase, indicating nothing essential about Aristotle's position.

Robinson is quick to point out, however, that he does not take Aristotle's dualism to have been equivalent to Descartes'. It is, he says, "more sophisticated" (p. 132) than Descartes' because of the hylomorphic (i.e., matter and form) relation posited between body and mind is "more intimate" (p. 132) than the simple causal relation proposed by Descartes. His attempts, however, to articulate the differences between Aristotle's and Descartes dualisms are obscure. Most clearly, he notes (pp. 141-142) that for Aristotle the conscious subject is the compound of mind and body, rather than, as for Descartes, the mental substance alone, somehow "trapped" in the body. Thus, Aristotle's theory goes some way towards explaining why consciousness cannot exist apart from a body (viz., it requires bodily sense organs in order to get thought-objects to be conscious of). Robinson does little, however, to explain just how Aristotle's supposed dualism differs from Descartes' without itself becoming non-dualistic.

In response to Robinson, Nussbaum (1984) rightly points out some of the tremendous differences between Aristotle's and Descartes' positions. The most important of these has to do with the metaphysical scope of Aristotle's hylomorphism as opposed to Descartes' dualism. Dualism addresses only the issue of the relation of the body to the mind (or soul). Hylomorphism, by contrast, addresses the much broader question of just what a substance -- any substance -- is. The application of this framework to the mind-body problem (and I use the term "mind" here quite broadly, recognizing that Aristotle's psuchê does not map on to our "mind" very exactly) is but a special case of a larger metaphysical position. To put things perhaps more concretely, dualism has nothing to say about the existence of chairs and houses, whereas hylomorphism is specifically directed at just such problems; the difference between a pile of bricks and a building is, roughly, that the building-form has been combined with brick-matter to result in a new kind of thing; one that can function as a shelter. Neither the bricks alone, nor the building-form alone (whatever that might be) could do that.

Between Rounds: Functionalism Licks its Wounds

Another well-known attempt to explicate Aristotle's theory is Christopher Shields' (1988) paper, "Soul and body in Aristotle." Shields considers four options with respect to the interpretation of Aristotle: (1) that the psuchê is identical with the body, (2) that the psuchê is an attribute of the body, (3) that the body "constitutes" the psuchê, and (4) that the psuchê is an immaterial substance. The first of these options -- identity theory -- is quickly dispensed with: Aristotle himself says in the Metaphysics, "when the [components of some thing] have been broken up, something no longer exits...but the elements [continue to] exist (1041b). If body and psuchê were identical, one could not cease to exist and the other continue to exist.

The second option, attribute theory, is described by Shields as being the claim that "persons are material substances which none the less have immaterial properties which are causally or non-causally necessitated by physical states of the body" (p. 112). For instance, we may continue to talk coherently about thoughts and beliefs as we traditionally have as long as we recognize that they are immaterial properties of the activity of the brain (in much the same way we may talk about the value of a house, even though we recognize that it is ontologically dependent -- though obviously in quite complex ways -- on the matter of which the house, and perhaps other nearby objects, are constructed). Shields identifies Barnes (1971-1972) as the primary advocate of this position, and glosses his argument as follows:

    1. Persons have some immaterial states;
    2. These cannot be states of the soul, since it is not substantial;
    3. Therefore, they must be states of the body or compound [of body and soul], both of which are material;

Therefore, Aristotle is an attribute theorist. (p. 112)

Shields rejects premise 2, "on the ground that souls are forms and so are substantial" (p. 112). At first blush this would seems to be a highly tendentious claim, dependent entirely on how one chooses to interpret "substance." The threat of equivocating between the Aristotelian and normal contemporary meanings looms large. Shields recognizes this, however, admitting that "the possibility that Aristotle is any sort of attribute theorist collapses into the question of whether the soul is constituted by matter," and thus moves on to option 3; viz., that the body constitutes the psychê.

The notion of "constitution" being used here is a tricky one. Shields defines it thus: "Let us say that the body constitutes the [psuchê] if and only if at any given point in its history, the [psuchê] has all and only the non-historical and non-modal properties the body has" (p. 113). To understand these caveats, it may be easier to work with the example of a house. Imagine a certain house which is the home of a man named Klink. If it were identical with Klink's home, you would not be able to say anything about it qua house that cannot be said about it qua Klink's home. One thing that can be said about the house, however, is that it was previously owned by someone else, say another man named Krank. It is not true, however, of Klink's home that it was previously owned by Krank. It was not then Klink's home. Klink's home was then someplace else, presumably. Thus the house and the home are not identical. According to Shields' definition of "constitution," however, historical properties, such as this one, are excluded from the constitution relation, so this argument cannot be run against the claim that the house constitutes Klink's home.

Another thing that could be said of the house is that it could possibly have been owned by someone else now (if, for instance, Klink had died before buying it). In the situation in which Klink were dead, however, it would not be right to say that Klinks' home could possibly be owned by someone else (for there would not be a "Klink's home" to own). Thus, again, they are shown not to be identical. Possibility, however, is a modal property, and these are excluded from the definition of constitution. So, if all the other properties hold -- e.g., that both the house and the home can be said to be painted white -- this house may be said to constitute Klink's home, but not be identical with it.

Among the properties that both the constituting and the constituted thing must share are all their causal properties. For instance, if a storm wrecks the house, it must also wreck the home. It is on this ground that Shields attempts to refute the idea that the body, in Aristotle, may be said to constitute the psuchê. To do so he cites Aristotle's own words to the effect that (1) the psuchê cannot be moved, (2) cannot be generated out of pre-existing stuff, (3) cannot be divided, and (4) is not decomposable into elements. All of these, however, are causal properties of the body: viz., it can be moved, generated, divided, and decomposed. If the body constituted the psuchê, however, they would be causal properties of the psuchê as well. This point figures particularly crucially in the present discussion because Shields next writes that the most plausible form of this sort of constitutionalism is contemporary functionalism. So it would thus seem that Shields believes that Aristotle was not a functionalist. As I shall soon show, however, Shields would shortly change his position dramatically.

Having rejected the first three options for interpreting Aristotle's view of the relation between psuchê and body, Shields opts for the fourth one: that the psuchê is an immaterial substance. He is quick to point out, however, that he does not believe Aristotle's position to have been the same as Descartes'. Instead of the psuchê being an immaterial substance utterly independent of the body, as in Descartes, Shields argues that Aristotle was a "supervenient dualist." The definition Shields gives of supervenient dualism is very -- one is inclined to say "overly" -- complicated. In essence, it comes down to the idea that the immaterial substance of the psuchê is in some (not very well-specified) way ontologically dependent on the material substance of the body, but not necessarily this body, or even a body very much like this one. Now except for the claim that this form of dependence, whatever it may be precisely, results in an immaterial substance being produced, this position sounds very much like contemporary functionalism. But recall that functionalism is a position that Shields had rejected in his discussion of constitutionalism. Recall also that it strongly implies the "transportability thesis" that psuchai can be moved from one "body" (biological, computational, or what have you) to another, assuming that the new "body" is suitably arranged to receive it.

Round 2: Functionalism Goes on the Attack

The question of Aristotle and computational functionalism was finally blown wide open when Shields (1990) bluntly asserted that "Aristotle and contemporary functionalists share deep theoretical commitments. So deep are these commitments that it is fair to regard Aristotle as the first functionalist" (p. 19). This seems to be a flat contradiction of his 1988 claim that functionalism is a form a constitutionalism, and that constitutionalism is an inadequate characterization of Aristotle's position. Gone from the 1990 paper is the careful, subtle argumentation of the 1988, replaced by a tendentious, quasi-historical argument that leads to a radical new view of Aristotle. I will try to show that this view goes much too far and is, in fact, false.

Shields (p. 20) argues that Aristotle's theory was a response to theoretical pressures analogous to those that gave rise to contemporary functionalism; viz., the need to remain within the confines of materialism and the recognition that physicalist versions of materialism are too constraining to be plausible. He responds to Robinson's caution that Aristotle was committed to conscious phenomena that have no place in strict functionalism with the claim that "weak" functionalism need not restrict the use of "mentalist vocabulary." Not content to leave it at that, however, he continues that because Aristotle sometimes presented definitions of mental states that do not include such vocabulary (such as anger being the heating of the blood around the heart), "there is reason to suppose that Aristotle accepts strong functionalism" (p. 28).

Most striking about Shield's 1990 thesis, however, was the confidence with which he asserts that Aristotle wholly endorsed the contemporary "transportability" thesis (viz., that psuchai can be moved from one material base to other possibly quite different ones). His defense of this radical interpretation is based on what must be regarded as dubious textual evidence, at best.

First, in a passage in the De anima (412b), Aristotle claims that the eye is defined by the function of seeing. Shields takes this to mean that Aristotle believed that anything that sees is an eye. In a certain sense this is true, but Aristotle gives no hint of believing that anything other than a conventional, biological eye could possibly see. The possibility is simply given no consideration. Shields has taken the comment out of its context. Aristotle's point here was that a dead eye is, in a certain sense, no longer an eye because it can no longer see, not that something else, endowed with sight, would therefore be an eye endowed with psuchê. This latter possibility seems literally to have never occurred to him.

Second, in a passage in De anima (408b) Aristotle speculates that if an old man had his eyes replaced with a younger man's eyes he would "see just as a young man." Shields construes this as meaning that "one could gradually replace body parts at will with others of the right sort [italics added]...and still end up with a functioning human being". (p. 21). But again, there is no indication anywhere that Aristotle believed that anything but the conventional biological parts could possibly be "of the right sort." There is no question of prosthetic eyes here.

Finally, in the Metaphysics, Aristotle asks the following question: "the form of man always appears in flesh and bones and these sorts of parts; are these, therefore, the parts of the form and account [of man]?" He then answers his own question, "No, they are but matter, but because [man is not seen] coming to be in other [materials], we are not able to separate them" (1037a-b). On this basis Shields argues that in Aristotle's mind, "'nothing hinders' [man's] being realized in other ways" (p. 23). There is little to warrant this inference, however. At best Aristotle is saying that we cannot tell if people could be realized in other materials. At worst it is simply inconceivable to him that it could be done in any other way. One can only be stunned at the anachronism that seems to be being perpetrated by Shields in such interpretations. There is simply no evidence that the notion transportability of psuchai was ever seriously considered by Aristotle.

In a much more sober article published in 1992, Myles Burnyeat argues against the claim that Aristotle was a functionalist in the modern sense of the term. His argument, like many others, is premised on the belief that Aristotle, unlike contemporary functionalists, thought awareness to be a crucial part of mental processes. Burnyeat goes further than most however, claiming, contra Sorabji (1974), that when Aristotle says that perception results from a sense organ being "affected" by the sensed object, he is not referring to a physiological change (e.g., the eye-jelly becoming red when a red thing is perceived). It is, rather, according to Burnyeat, a case of awareness of the object being realized in the organ (e.g., the eye "registering" red). As evidence, he turns to another of Aristotle's analogies: that the eye perceiving is like the block of wax receiving an impression from a stamp. Burnyeat notes that when the a circular object is pressed into a square block of wax, the block does not itself become circular; "it has registered, and now displays, a circle" (p. 22). Thus, he continues, the eye perceiving a red object does not itself become red; it only registers the red impression made upon it. This "registration," according to Burnyeat, is only in awareness, not in its physical being. If so, Burnyeat goes on, functionalism, which because of its essential materialism is trying to outline an account of the physical process of perception (among other mental activities), is at odds with the Aristotelian project.

A passage from De anima that Burnyeat himself cites seems to show where he may have gone astray: "What then is smelling apart from being affected? Or is smelling also awareness...?" (II.12, italics added). It seems that Burnyeat is trying to drive a wedge between the physical and the conscious where Aristotle himself resisted doing so: perception is clearly said to be both the organ "being affected" (presumably physiologically) and a kind of "awareness" in the organ. Contrary to Burnyeat's implication, most contemporary functionalists would have little difficulty with this. They would simply concede that they have no account of the "awareness" side of the equation. Burnyeat tries to rebut this, however. He argues that the parallel the functionalists see between Aristotle and themselves is illusory because Aristotle took vital functions, rather than physical ones, to be basic. According to Burnyeat the aim for Aristotle, in contrast to us, was not to explain vital processes in terms of physical ones. Because matter was considered to be so lowly and "insubstantial" -- mere potential -- it could not possibly ground an explanation of life. Because Aristotle's conception of matter was so radically different from the one we have inherited from the Cartesian revolution, we could not possibly believe Aristotle's theory of psuchê; nor he ours. Thus, according to Burnyeat, he could not possibly have been a functionalist. As Burnyeat puts it, "if we want to get away from Cartesian dualism, we cannot do it by traveling backwards to Aristotle, because although Aristotle had a non-Cartesian concept of the soul, we are stuck with a more or less Cartesian concept of the physical. To be truly Aristotelian, we would have to stop believing that the emergence of life or mind requires an explanation" (p. 26).

Split Decision?: Functionalists Make a Concession

Nussbaum and Putnam (1992) respond directly to Burnyeat's article, but they do not openly support Shields' radical claims. First, they repeat many of the arguments that Nussbaum (1984) had made against Robinsion (1983) with respect to hylomorphism being a much broader metaphysical thesis that cannot be properly evaluated when the discussion is restricted to the question of the psuchê; if you deny the importance of matter with respect to the psuchê, then you are committed to denying it with respect to, say, chairs as well. Second, with this argument in hand, they deny outright that Aristotle considered life to be essentially inexplicable:

when Aristotle argues against materialistic reductionism he could not possibly be relying on the 'primitive' nature of intentionality, or on the inexplicable character of life and mind -- for the simple reason that his defence of form is meant to apply...across the board to all substances, whether or not they have 'mind' or even life. (Nussbaum & Putnam, 1992, p. 30)

Nussbaum and Putnam then present textual support for the claim that Aristotle was crucially concerned with the physiological side of the psychological equation, not only from De anima, but from De motu animalium and De sensu. They regard it as "especially unwise to regard [De anima] as the [original italics] central text when discussing this particular problem" (p. 37) because Aristotle himself says in De anima he is restricting himself to "structural" matters with respect to the psuchê, issues of the physiological base having been discussed other works. Thus, absence of evidence should, here especially, not be interpreted as evidence of absence.

Finally they get down to the matter of whether or not Aristotle should be characterized as a functionalist. Aristotle rejects Democritean reductive materialism and Platonic idealism in favor of a position in which the organization, or form, of matter is key to understanding the nature of a thing, even when that "thing" is the psuchê. Certainly, however, the kind of organization Aristotle had in mind was not computational. Of course, this was not made very clear when Putnam made his famous quip about functionalists having the same interest in form as Aristotle in the 1970s. It all seemed much more obvious to them in 1992, however, by which time Putnam had repudiated computational functionalism (1988). This is a much weaker notion of what counts as functionalism than is found in Shields, and it makes Aristotle a distant cousin of contemporary functionalists, many times removed, rather than a direct lineal ancestor.


Nussbaum and Putnam have, I think, gotten things approximately right here (though there is an attempt to assimilate Aristotle to Wittgenstein near the end of the piece of which one should be deeply suspicious). Even so, I believe they read Aristotle a little too liberally. Contemporary functionalism puts virtually no restriction on what kind of matter might underpin a particular computational state, save that it be "complex enough" to be able to realize the computational state in question. Aristotle, I think, would have had no truck with this. He is quite clear that the only material object that has the potential to be a living thing is a (biological) body. In fact he goes so far as to say that only a living body has this potential (and, thus, that this potential has already been actualized) (De anima, 412b). Even dead bodies, it would seem, no longer have the potential for life.

Now, if Aristotle was not the sort of fellow who could envision bringing a dead body back to life (i.e., rejecting the possibility that after death it retains within it a potential for life that could be "re-actualized" by the "application" of psuchê), it would seem a fair bet that neither was he the sort who would attribute that potential to computers (or thermostats, or liquid running through plastic tubes, or assemblages of beer cans and string, to use a few of contemporary cognitive scientists' more fanciful suggestions). Perhaps it is fair to say that he was a functionalist in the general sense that he believed the psuchê to be the functioning of a particular body, but it seems unlikely that he would have endorsed even a limited form of the "transportability" thesis (except perhaps in the limiting case of an identical clone down to, say, the molecular level). The kind of life a body has is, for Aristotle, too intimately connected to the kind of body it has for it to be shifted around willy-nilly. In fact, he is quite explicit about this in the oft-ignored Book I of De anima: "[Other philosophers of the psuchê] do not try to determine anything about the nature of that which is to receive [the psuchê], as if it were possible, as in the Pythagorean myths, that any psuchê could be clothed in any body -- an absurd view, since it is apparent that each body has its own particular form and shape" (407b, translation from Everson, 1995). If Aristotle is right about this, then it is, perhaps, Pythagoras we should be looking to as a precursor to the functionalists, not Aristotle.

In summary, then, Aristotle might be considered to have been a functionalist in the very general sense that he did not believe it possible to explain life and mind in reductive physiological terms. His definitions of vital processes, such as perception, are functional. There is no hint, however, that he believed, even in principle, that these functions might be "lifted out" of the body in which they are found, and moved or reproduced somewhere else. In this Aristotle is at odds with contemporary functionalism. That is, his position is distant enough from that advocated by contemporary functionalists that it seems more misleading to include him among them, than to regard his theory as something apart -- something sui generis, as Sorabji called it. The temptation to assimilate it to our current accounts, partly in an effort to gain for them and air of ancient authority, is ever-present. As far back as the 6th century John Philoponus noted that "commentators on Aristotle are inclined to try to attribute to him doctrines which they themselves think sound." (ca. 550/1991, p. 12).[10] Ancient as the temptation is, it is one that we should resist. If we can, we may find that Aristotle's account of the psuchê is a theory from which we can still learn a thing or two.

(soon after the paper was accepted for publication in History of Psychology)

At a talk in 1997 Ronald de Sousa suggested that a passage from the opening of Metaphysics, VII.11 shows that Aristotle might have been a functionalist after all. It reads:

Another question is naturally raised, viz. what sort of parts belong to the form and what sort not to the form, but to the concrete thing. Yet if this is not plain it is not possible to define any thing; for definition is of the universal and of the form. If then it is not evident what sort of parts are of the nature of matter and what sort are not, neither will the formula of the thing be evident. In the case of things which are found to occur in specifically different materials, as a circle may exist in bronze or stone or wood, it seems plain that these, the bronze or the stone, are no part of the essence of the circle, since it is found apart from them. Of things which are not seen to exist apart, there is no reason why the same may not be true, just as if all circles that had ever been seen were of bronze; for none the less the bronze would be no part of the form; but it is hard to eliminate it in thought. E.g. the form of man is always found in flesh and bones and parts of this kind; are these then also parts of the form and the formula? No, they are matter; but because man is not found also in other matters we are unable to perform the abstraction.

When one reads the rest of the passage, however, Aristotle is decidedly ambivalent, and recognizes the danger of falling in with the Pythagoreans, whom he mentions by name--a fate he seems to think to be foolish.[11]


Barnes, J. (1979). Aristotle's concept of mind. In J. Barnes, M. Schofield, & R. Sorabji (Eds.), Articles on Aristotle: Vol. 4. Psychology and aesthetics (pp. 32-41). London: Duckworth. (Originally published in Proceedings of the Aristotelian Society, 1971-2)

Burnyeat, M. F. (1992). Is an Aristotelian philosophy of mind still credible? (A draft). In Nussbaum, M. C. & Rorty, A. O. (Eds.), Essays on Aristotle's De anima (pp. 15-26). Oxford: Clarendon Press.

Durrant, M. (Ed.) (1993). Aristotle's De anima in focus. London: Routledge.

Everson, S. (1995). Psychology. In J. Barnes (Ed.), The Cambridge companion to Aristotle (pp. 168-194). Cambridge, England: Cambridge University Press.

Feigl, H. (1970). Mind-body, not a pseudo-problem. In C. V. Borst (Ed.), The mind-brain identity theory (pp. 33-42). London: Macmillan. (Original work published 1960)

Fodor, J. A. (1968). Psychological explanation: An introduction to the philosophy of psychology. New York: Random House.

Fodor, J. A. (1975). The language of thought. Cambridge, MA: Harvard University Press.

Fodor, J. A. (1981). Representations: Philosophical essays on the foundations of cognitive science. Cambridge, MA: MIT Press.

Lawson-Tancred, H. (1986). Introduction. In Aristotle, De anima (H. Lawson-Tancred, Trans., pp. 11-116). London: Penguin.

Nussbaum, M. C. (1978). Aristotle's De motu animalium. Princeton, NJ: Princeton University Press.

Nussbaum, M. C. (1984). Aristotelian dualism: Reply to Howard Robinson. In J. Annas (Ed.), Oxford studies in ancient philosophy (Vol. 2, pp. 197-207). Oxford: Clarendon Press.

Nussbaum, M. C. & Putnam, H. (1992). Changing Aristotle's mind. In Nussbaum, M. C. & Rorty, A. O. (Eds.), Essays on Aristotle's De anima (pp. 27-56). Oxford: Clarendon Press.

Philoponus, John (1991). On Aristotle on the intellect (W. Charlton, Trans.). London: Duckwoth. (Original work written ca. 550)

Place, U. T. (1956). Is consciousness a brain process? British Journal of Psychology, 47, 44-50.

Putnam, H. (1975). Minds and machines. In H. Putnam, Mind, language, and reality: Philosophical Papers (Vol. 2). Cambridge: Cambridge University Press. (Original work published 1960)

Putnam, H. (1975). Philosophy and our mental life. Philosophical papers: Vol. 2. Mind, language, and reality (pp. 291-303). Cambridge: Cambridge University Press. (Paper originally presented in 1973)

Putnam, H. (1988). Representation and reality. Cambridge, MA: MIT Press.

Robinson, H. M. (1978). Mind and body in Aristotle. Classical Quarterly, N.S. 28, 105-124.

Robinson, H. M. (1983). Aristotelian dualism. In J. Annas (Ed.), Oxford studies in ancient philosophy (Vol. 1, pp. 123-144). Oxford: Clarendon Press.

Rorty, R. (1970). Incorrigibility as the mark of the mental. Journal of Philosophy, 67, 399-424.

Ryle, G. (1949). The concept of mind. New York: Barnes & Noble.

Shields, C. (1988). Soul and body in Aristotle. In J. Annas (Ed.), Oxford studies in ancient philosophy (Vol. 6, pp. 103-136). Oxford: Clarendon Press.

Shields, C. (1990). The first functionalist. In J-C. Smith (Ed.), Historical foundations of cognitive science (pp. 19-33). Dordrecht, Netherlands: Kluwer.

Smart, J. J. C. (1970). Sensation and brain processes. In C. V. Borst (Ed.), The mind-brain identity theory (pp. 52-66). London: Macmillan. (Original work published 1959)

Sorabji, R. (1974). Body and soul in Aristotle. Philosophy, 49, 63-89.

Author Note

Christopher D. Green, Department of Psychology, York University, North York, Ontario, M3J 1P3, CANADA. E-mail: WWW:


[1] Lest there be any confusion, this paper does not discuss the possibility that there may be some sort of connection between Aristotle's position on the psuchê and position called functionalism that was advocated by Dewey, Angell, Carr, and others during the late 19th and early 20th centuries.

[2] The are many different specific formulations of behaviorism. The one discussed here is the one entertained by philosophers, particularly Gilbert Ryle (1949), during the middle of the 20th century. Others, formulated by psychologists such as Watson, Tolman, Hull, and Skinner, differ somewhat.

[3] See, in particular, Feigl (1960/1970) and Smart (1959/1970).

[4] I have made use of several translations of De anima in the writing of this paper. Among these were H. Lawson-Tancred's (1986, Penguin), R. D. Hicks' (1993, in M. Durrant's Aristotle's De anima in focus, Routledge), and W. S. Hett's (1986, Loeb). I have also, of course, had some recourse to J. A. Smith's (1941, in R. McKeon's The basic works of Aristotle, Random House), and J. Barnes' (1984, in The complete works of Aristotle, Princeton).

[5] Scylla and Charybdis were said in Greek myth to be two monsters that guard the Straits of Messina, between Italy and Sicily. The story of Odysseus' navigation past them is told in Book XII of the Odyssey.

[6] Sorabji (p. 70), in fact, assimilates Barnes' view to that of the Cartesian, arguing that the true materialist (he cites Rorty, 1970) must give up talk of mental properties altogether.

[7] Only the "active intellect," discussed briefly and obscurely in III.5 of De anima, was said to be immortal, unchangeable, and separable from the body. It apparently flies in the face of the rest of Aristotle's theory of the psuchê, and thus haunts much of the current discussion, in the sense that few discuss it openly but everyone knows it is there, hanging in the background. As do most, I will discuss it below only very briefly, for if it is taken at face value, then there is no point in Aristotle's theory as an interesting alternative to Cartesian dualism much at all. The rest of the theory, however, has much of interest to offer.

[8] Again, this should not be confused with the evolutionary functionalism of Dewey, Angell, Carr et al.

[9] See, in particular, Putnam (1960/1975) and Fodor (1968, 1975, 1981).

[10] I would like to thank Simon Kemp for brining this passage to my attention.

[11] I would like to thank Michael Gemar for bringing this passage to my attention.