Aristotle on Explanation

Book 1 chapter 1 of Parts of Animals provides an overview of Aristotle’s perspective on explanation in general. It is a nice synthetic text that brings together many of Aristotle’s core concerns, and shows his vision of how natural science ought to fit in with broader philosophy.

He begins by distinguishing between mere acquaintance with an area of study and being educated in it. “For an educated [person] should be able to form a fair judgment as to the goodness or badness of an exposition” (Complete Works, Barnes ed., vol. 1, p. 994). This seems to apply to any subject whatsoever.

Next he raises the more specific question of method. “It is plain then that, in the science which inquires into nature, there must be certain canons, by reference to which a hearer shall be able to criticize the method of a professed exposition, quite independently of the question whether the statements made be true or false” (ibid).

Continuing to emphasize the critical thinking that is the mark of an educated person, he makes it explicit that some of the most important questions about a subject are what I would call second-order questions, having to do with how we ought to approach the matter at hand. The educated person will give due emphasis to these, rather than naively rushing to deliver judgments on questions of fact.

“Ought we, for example (to give an illustration of what I mean) to begin by discussing each separate substance — man, lion, ox, and the like — taking each kind in hand independently of the rest, or ought we rather to lay down the attributes which they have in common in virtue of some common element of their nature? For genera that are quite distinct present many identical phenomena, sleep, for instance, respiration, growth, decay, death, and other similar affections and conditions…. Now it is plain that if we deal with each species independently of the rest, we shall frequently be obliged to repeat ourselves over and over again; for horse and dog and man present every one of the phenomena just enumerated” (ibid).

The educated person looks for explanations, not just facts or correspondences. The specific “dogginess” of a dog, for example, does not explain its sleeping, breathing, and so on. Instead these activities, which it shares with many other animals, are explained by natures common to all of them.

Further, the kind of method Aristotle commends to us is not a matter of following recipes by rote. Instead, it is a thinking approach that involves persistently following the thread of explanations wherever it leads.

“So also there is a like uncertainty as to another point now to be mentioned. Ought the student of nature follow the plan adopted by the mathematicians in their astronomical demonstrations, and after considering the phenomena presented by animals, and their several parts, proceed subsequently to treat of the causes and the reason why; or ought he to follow some other method? Furthermore, the causes concerned in natural generation are, as we see, more than one. There is the cause for the sake of which, and the cause whence the beginning of motion comes. Now we must decide which of these two causes comes first, which second. Plainly, however, that cause is the first which we call that for the sake of which. For this is the account of the thing, and the account forms the starting-point, alike in the works of art and in works of nature. For the doctor and the builder define health or house, either by the intellect or by perception, and then proceed to give the accounts and the causes of each of the things they do and of why they should do it thus” (p. 995).

He raises the question of which kind of cause comes first, because he wants to suggest a different answer from that of the pre-Socratic “physicists” who attempted to explain everything by properties of different kinds of matter. Elsewhere he says that Plato and the atomist Democritus (whose writings are lost) did better than others at following the thread of explanation, but he considers the elaborated account of ends or “that for the sake of which” to be one of his own most important contributions.

Notably he only mentions two kinds of cause here, rather than the classic four. Similarly, there are passages in other texts where he lists a different number of categories than the canonical ten from the Categories. Later authors often viewed things like causes and categories in a reified, univocal way, as susceptible to exact enumeration. But for Aristotle, these are abstractions from a concrete reality that comes first, to be wielded in a context-sensitive way, so the canonical enumerations are not absolute.

Aristotle’s understanding of the “beginning of motion” is different from that promoted by early modern physics. Conventionally in the reading of Aristotle, the “beginning of motion” is associated with the efficient cause, and these two terms are understood in a somewhat circular way, which is really informed by some broadly intuitive sense of what a “beginning” of motion is. Early modern writers assumed that this “beginning” must be some kind of immediate impulse or force. Aquinas associated it with God’s act of creation and with the free acts of created beings. For Aristotle himself it is neither of these.

My best reading of efficient cause is that it is the means by which an end is realized. In many cases the end is realized not by just one means but by a hierarchy of means (e.g., art of building, carpenter, carpenter’s hammer, hammer’s blow). Aristotle and the scholastics emphasized the top of such hierarchies (e.g., the art of building for Aristotle; God or some metaphysical principle for the scholastics), whereas the early moderns emphasized the bottom (e.g., the hammer’s blow), akin to the proximate cause of concern to liability lawyers. For Aristotle, the art of building and not the hammer’s blow is the true “beginning” of the motion of house construction, because it provides the guiding thread of explanation for the whole process of building the house. But even the art of building is still just a means that gets its meaning from the reasons why we would want to build a house in the first place.

He continues, “Now in the works of nature the good and that for the sake of which is still more dominant than in works of art, nor is necessity a factor with the same significance in them all; though almost all writers try to refer their accounts to this, failing to distinguish the several ways in which necessity is spoken of. For there is absolute necessity, manifested in eternal phenomena; and there is hypothetical necessity, manifested in everything that is generated as in everything that is produced by art, be it a house or what it may. For if a house or other such final object is to be realized, it is necessary that first this and then that shall be produced and set in motion, and so on in continuous succession, until the end is reached, for the sake of which each prior thing is produced and exists. So also is it with the productions of nature. The mode of necessity, however, and the mode of demonstration are different in natural science from what they are in the theoretical sciences [e.g., mathematics]…. For in the latter the starting-point is that which is; in the former that which is to be. For since health, or a man, is of such and such a character, it is necessary for this or that to exist or be produced; it is not the case that, since this or that exists or has been produced, that of necessity exists or will exist. Nor is it possible to trace back the necessity of demonstrations of this sort to a starting-point, of which you can say that, since this exists, that exists [as one might do in mathematics]” (ibid).

In Aristotle’s usage, “nature” applies to terrestrial things that are observably subject to generation and corruption. He earlier referred to astronomical phenomena like the apparent motions of the stars and planets as “eternal” because on a human scale of time, these are not observably subject to generation and corruption. For Aristotle, absolute necessity could only apply to things that are absolutely unchanging. We may have a different perspective on astronomy, but that does not affect the logical distinction Aristotle is making. His key point here is that things subject to generation are not subject to absolute necessity. Leibniz took this a step further and argued that hypothetical necessity is the only kind there is. Kant, in arguing that hypothetical and disjunctive judgment (“if A then B” and “not both A and B“) are more fundamental than categorical judgment (“A is B“), made a related move.

Hypothetical necessity has a particular form that is worth noting. As Aristotle points out in the quote above, under hypothetical necessity “it is not the case that, since this or that exists or has been produced, that of necessity exists or will exist”. To give a positive example, hypothetical necessity says that to continue living, we must eat. But it does not in any way dictate a particular series of motions that is the only way this can be accomplished, let alone the whole series of eating-related actions throughout one’s life. Neither does it dictate that we will eat in any particular instance.

How we meet a particular need is up to us. The reality of this flexibility built into nature is all we need to explain freedom of action. Humans can also affirmatively embrace commitments and act on them; that too is up to us. Freedom is not an arbitrary or supernatural power; it simply consists in the fact that nature is flexible, and many things are up to us.

Aristotle contrasts the way a thing is naturally generated with the way it is. “The best course appears to be that we follow the method already mentioned — begin with the phenomena presented by each group of animals, and, when this is done, proceed afterwards to state the causes of those phenomena — in the case of generation too. For in house building too, these things come about because the form of the house is such and such, rather than its being the case that the house is such and such because it comes about thus…. Art indeed consists in the account of the product without its matter. So too with chance products; for they are produced in the same way as products of art” (pp. 995-996).

“The fittest mode, then, of treatment is to say, a man has such and such parts, because the essence of man is such and such, and because they are necessarily conditions of his existence, or, if we cannot quite say this then the next thing to it, namely, that it is either quite impossible for a man to exist without them, or, at any rate, that it is good that they should be there. And this follows: because man is such and such the process of his development is necessarily such as it is; and therefore this part is formed first, that next; and after a like fashion should we explain the generation of all other works of nature” (p. 996).

This way of reasoning backwards from an essence to its prerequisites is complemented by the fact that for Aristotle (and Plato) essences themselves are a prime subject of investigation, and not something assumed. “Begin with the phenomena”, he says.

Many 20th century philosophers have objected to presumptuous talk about the “essence of man”, and to any explanation in terms of essence. But these objections presuppose that the essence is something assumed, rather than being an object of investigation as it clearly was for Plato and Aristotle. Here also it is needful to distinguish between what we might call the distinguishing essence of humanity used to pick out humans — e.g., “rational/talking animal” — and what Leibniz later called the complete essence of each individual. Clearly also, the parts of the human body do not follow directly from “rational/talking animal”, but from many other attributes “presented in the phenomena”. It turns out that humans share these attributes with other animals, and they can therefore be conceptualized as attributes of common genera to which we and those other animals belong.

Because essences themselves are a prime subject of investigation and are ultimately inferred from phenomena, the kind of teleological reasoning Aristotle recommends always has a contingent character, which is how it naturally accounts for what the moderns call freedom. This contingency is built into in the “hypothetical” character of hypothetical necessity.

“Does, then, configuration and color constitute the essence of the various animals and their several parts? For if so, what Democritus says will be correct…. And yet a dead body has exactly the same configuration as a living one; but for all that it is not a man. So also no hand of bronze or wood or constituted in any but the appropriate way can possibly be a hand in more than name. For like a physician in a painting, or like a flute in a sculpture, it will be unable to perform its function” (p. 997).

Aristotle was the historic pioneer of “functional” explanation. Here he insists that the essences of living beings and their parts must be understood in terms of their characteristic activities. This development for the sake of biology parallels the deeper development of the meaning of “substance” in the Metaphysics as “what it was to be” a thing, and as actuality and potentiality.

“If now the form of the living being is the soul, or part of the soul, or something that without the soul cannot exist; as would seem to be the case, seeing at any rate that when the soul departs, what is left is no longer an animal, and that none of the parts remain what they were before, excepting in mere configuration, like the animals that in the fable are turned into stone; if, I say, this is so, then it will come within the province of the natural scientist to inform himself concerning the soul, and to treat of it, either in its entirety, or, at any rate, of that part of it which constitutes the essential character of an animal; and it will be his duty to say what a soul or this part of a soul is” (ibid).

Here it is important that we consider soul in the “phenomena first” way that Aristotle develops it.

“What has been said suggests the question, whether it is the whole soul or only some part of it, the consideration of which comes within the province of natural science. Now if it be of the whole soul that this should treat, then there is no place for any philosophy beside it…. But perhaps it is not the whole soul, nor all of its parts collectively, that constitutes the source of motion; but there may be one part, identical with that in plants, which is the source of growth, another, namely the sensory part, which is the source of change of quality, while still another, and this is not the intellectual part, is the source of locomotion. For other animals than man have the power of locomotion, but in none but him is there intellect. Thus it is plain that it is not of the whole soul that we have to treat. For it is not the whole soul that constitutes the animal nature, but only some part or parts of it” (p. 998).

Aristotle’s opposition to treating the soul as a single lump reflects his overall functional, activity-oriented, and phenomena-first approach.

“Again, whenever there is plainly some final end, to which a motion tends should nothing stand in its way, we always say that the one is for the sake of the other; and from this it is evident that there must be something of the kind, corresponding to what we call nature” (ibid).

Overall teleology always has to do with tendencies, not absolute determinations. He begins to wrap up this introduction by giving another example of the hypothetical necessity whose concept he pioneered.

“For if a piece of wood is to be split with an axe, the axe must of necessity be hard; and, if hard, must of necessity be made of bronze or iron. Now in exactly the same way the body, since it is an instrument — for both the body as a whole and its several parts individually are for the sake of something — if it is to do its work, must of necessity be of such and such a character, and made of such and such materials.”

“It is plain then that there are two modes of causation, and that both of these must, so far as possible, be taken into account, or at any rate an attempt must be made to include them both; and that those who fail in this tell us in reality nothing about nature” (p. 999).

Again, the two modes here are “that for the sake of which” and the phenomena associated with generation. Considering either of these in isolation yields an incomplete understanding, as we see respectively in bad scholasticism and bad empiricism.

“The reason why our predecessors failed to hit on this method of treatment was, that they were not in possession of the notion of essence, nor of any definition of substance. The first who came near it was Democritus, and he was far from adopting it as a necessary method in natural science, but was merely brought to it by constraint of facts. In the time of Socrates a nearer approach was made to the method. But at this period men gave up inquiring into nature, and philosophers diverted their attention to political science and to the virtues that benefit mankind” (ibid).

Socrates and Plato initially pioneered the notion of “that for the sake of which”, but in turning away from the phenomena of generation and becoming, they gave it a somewhat one-sided character.

The subtle way in which Aristotle wields the concept of essence avoids treating it as an absolute, or as something strictly univocal. In any given context, there is a clear relative distinction between essence and accident, but the distinction is not the same across all contexts. Hypothetical necessity provides the mechanism by which what is “accident” at one level of analysis can be incorporated into “essence” at another level. (See also Hermeneutic Biology?; Aristotelian Causes; Secondary Causes; Aristotle’s Critique of Dichotomy; Classification.)

The Human in Siger of Brabant

Those whom modern scholars called Averroists were supposed to be unoriginal, dogmatic followers of Averroes. This turns out to be as inaccurate as the supposition that the Latin scholastics as a whole were unoriginal, dogmatic followers of Aristotle.

At issue here is what it is to be human, and in particular how the difficult Aristotelian concept of “intellect” relates to human beings. There were not just two but a wide variety of nuanced and well-argued positions on this.

Among the so-called Averroists, Siger of Brabant (1240-1280) is the best known name, but no full book has yet been devoted to his work. According to Alain de Libera, in his later works Siger developed original responses to Thomas Aquinas’ famous critique of Averroes.

Siger argued against Aquinas that the act of thought is not purely immanent but simultaneously immanent and transitive. That is to say, for Siger it is immanent in the human, but transitive in the separate intellect. While affirming a “separate” intellect, Siger emphasized against Aquinas that the total act of thinking is attributable to the whole human, and not just to the human’s intellective soul. Intellect is an “intrinsic operation” in the human that in a way does, and in a way does not, make it the “substantial form” and perfection of a material body. According to Siger, Aquinas’ claim that the intellective soul unequivocally is the substantial form of the body cannot be reconciled with Aquinas’ other claim that intellect as a power of the intellective soul is entirely independent of the body. Siger adopts Albert and Thomas’ term “intellective soul”, but for Siger only the animal and vegetative soul are united with the body in being. Intellective soul is naturally united with the body in operation but not in being, whereas Aquinas says they are united in being.

According to de Libera, Siger in his Questions on the Book of Causes argues that the form of the human is not simple, but is rather a composite comprising an intellect that “comes from outside” (in Aristotle’s phrase), and a vegetative and sensitive substance that is “educed from the power of matter” (de Libera, Archéologie du sujet vol. 3 part 1, p. 411, my translation). Intellect is said by Siger to be a “form subsistent in itself”. It is not a “substantial form” in the proper sense, which would imply that it was inherent in the human body. It is not in the body “as in a subject”. However, intellect has need of the human body (specifically, the phantasms of the imagination) as an object, and intellect is in turn attributable to the human as a whole, though it is not reducible to the biological organism. Intellect for Siger is neither the inherent form of the human nor a separate, external mover of the human, but a separate form with an operation that is intrinsic to the whole human, in which it participates by composition.

De Libera remarks in passing that the act of thought owes more to intelligible objects than to “intellect”. I would suggest that it is through language and culture and ethical practice that Aristotelian intellect “comes to us from outside”. We talking, encultured animals then acquire a spiritual essence that comes to be intrinsic to us, through our ethical practice, in which acquired intellect and animal imagination cooperate.

According to de Libera, for Siger “The ‘intelligent whole’ is composed of many psychic parts, which are not of the same nature, or of the same origin, or of the same ontological status” (p. 362).

Siger objects that Aquinas’ notion of intellect as united with the body in being “makes the act of thought a perfection of matter” (ibid). This makes the body intellect’s “subject of inherence”. But at the same time, applying Thomas’ own axiom that nothing is accomplished by a power separated from itself, Siger reproaches Thomas for being unable to account for “the integrality of the known” (p. 378), and specifically the knowledge of material things.

For Aquinas, establishing that there is an operation proper to the soul is essential to the possibility of the soul’s existence independent of the body, and thus to his philosophical argument for personal immortality. But Siger argues that in making intellect an operation proper (i.e., uniquely attributable) to the soul, Aquinas implicitly negates its attributability to the whole human. Intellection for Siger is “an operation common to the human composite as an integral whole” (p. 377). In other words, I think with my whole being, not just my “mind”.

De Libera concludes that Siger does preserve the possibility of personal immortality, which was a principal concern of Averroes’ critics. However, he finds that the texts do not support the claims of some recent scholars that Siger in his later works abandoned “Averroism” in favor of Thomism.

The phrase “form subsistent in itself”, according to de Libera, does not have the same meaning for Siger that it does for Thomas. Albert the Great had analyzed three logical possibilities for an “intermediate” kind of form that is neither fully separate nor inseparable from matter. According to de Libera, Siger’s work is consistent with this. Siger aimed at a mean between a Platonist excess of separation between form and matter, and what he perceived as a Thomist excess of union with respect to so-called substantial forms. De Libera does find, however, that Siger, like other authors, is too anxious to simplify the issues at stake, and that he goes too far in identifying the position of Aquinas with that of Alexander of Aphrodisias, who was regarded as having a “materialist” view of the human soul. He also says Siger goes too far in reducing Aquinas’ notion of form to the simple analogy of a stamp in wax.

De Libera meanwhile also raises doubts about Aquinas’ insistence on the absence of any intermediary between the intellective soul and the body. He notes that in a very different context, the Franciscan Augustinian Peter Olivi argued that the intellective soul is united with the body via the intermediary of the sensitive soul. Olivi’s position was rejected by the Council of Vienna in 1312.

De Libera accepts the notion of “substantial form” as genuinely Aristotelian, but appears to endorse the argument of Bernardo Carlos Bazán that Aquinas’ notion of intellective soul gives it a privileged ontological status that makes it more than a substantial form. According to Bazán, Aquinas’ anthropology from the very start goes beyond the Aristotelian hylomorphism that Thomas generally endorses. The form of a human in Aquinas — unlike anything in Aristotle — is such that it could not be the result of any natural generative process, but could only be created by God. Siger comes across as closer to Aristotle.

De Libera notes that in the wake of the English theologian Thomas Wylton (1288-1322), later so-called Averroists “invested massively” in a distinction between an inherent form and an assisting form, and regarded human intellect as an “assisting form”. (See also “This Human Understands”; “This Human”, Again; Averroes as Read by de Libera.)

Aquinas on the Soul

Lately I’ve repeatedly mentioned Thomas Aquinas (1225-1274), and I feel some additional due diligence is in order. Though I have browsed his major works, I am assuredly no Aquinas scholar, so I want to tread carefully. This is an exploration, and conclusions may be revised.

My currently interrupted arc treating Alain de Libera’s Archaeology of the Subject has brought to light some unfamiliar suggestions regarding Aquinas’ role in the formation of the modern concept of action as a central explanatory term. Act, action, and actuality are three distinct things in Aristotle, and they seem to be three different distinct things in Aquinas. We have to be careful that all these distinctions are not confused. So, I am embarking on a little detour to get a clearer sense of what they specifically mean in Aquinas.

The most famous theologian of the Catholic church, Aquinas is a very substantial figure whose work has given rise to diverse interpretations. His principal concern was what is called revealed theology, which properly speaking is outside my scope here, but he was perhaps best known (and initially controversial) for his philosophical theology, and for fusing discourses of theology and philosophy. Without ever losing sight of things he considered to be known by faith, he gave an unprecedented place to philosophical arguments in his theological works, and also developed a highly original purely philosophical theology, which he held to independently point in the same direction as his revealed theology.

Contrary to the myth that the Latin middle ages were dogmatically Aristotelian, the place of Aristotelian learning and the social status of philosophy in Aquinas’ lifetime were actually quite precarious, encountering widespread opposition from religious conservatives. Were it not for the conciliatory work of Aquinas and its eventual acceptance by the Church, conservatives might have succeeded in rolling back the great cultural advances that began in the 12th and 13th centuries with the influx of Arabic, Hebrew, and Greek learning into the hitherto rather barbarous world of Latin-speaking Europe. If I often sound critical of Aquinas and disagree with his extraordinarily original redeployment of some key Aristotelian terms, that should be taken in the context of this larger historical debt.

On the question of the soul, Thomist scholar Ralph McInerny explains in the Stanford Encyclopedia of Philosophy that Aquinas in questions 75 and 76 of the first part of Summa Theologica distinguishes between a substance and a “subsistent”. He also develops a concept of a being’s actus essendi or “act of existence”. Both of these details — which have no precedent in Aristotle — are new to me. This is the same part of Summa Theologica that de Libera was focusing on.

The human soul for Aquinas is not an independent spiritual substance as an angel would be; rather it is the subsistent substantial form and formal principle of an embodied human being. It makes the human what she is, but is not complete in itself. As a principle of a nature, it has no nature of its own, and is not a substance in its own right. Its nature is to be the formal element of a complete (embodied) substance.

According to McInerny, Aquinas stresses that “the soul exists in a living being as the substantial form of an animal”. Socrates as a human has all the vital activities of a living animal. For Aquinas none of these are distinctive activities of the soul itself, because they are involved with bodily functions. On the other hand, the intellect of Socrates is said by Aquinas to be a distinctive activity or “operation” of Socrates’ soul itself that involves no corporeal organ, and this operation is said to be able to exist independent of the body.

Aquinas acknowledges this to be an unnatural state, since the soul is not complete in itself. But he holds that it is enough to establish that the human soul has an operation that does not depend on a bodily organ, in order to show that the human soul is an incorporeal subsistent that can exist independent of the body. Souls of nonhuman animals have no nonbodily operation, and therefore are not immaterial subsistents. At the same time, the intellectual soul of a human is distinguished from an angel precisely because it is the substantial form of an animal.

Taking it as established that Socrates as an embodied human being is not the same as the soul of Socrates, Aquinas according to McInerny argues that Socrates and his soul nonetheless are both “subjects” of one identical activity or operation. Intellect is an activity of Socrates’ soul that is equally an activity of Socrates the complete human. Aquinas holds that for an animal with an intellectual operation, the intellectual soul and the animal (and vegetable) soul are one and the same.

McInerny summarizes, “In the case of other animals it is the animal itself, the living substance, that is the subject of the act of existence, and both soul and body have existence through the substance. Here in the human case, the soul is said to be the subject of the act of existence because it has its own operation.”

Rationality — or acting knowingly and willingly — “is the distinctive form that intelligence takes in human beings as animals. Rationality involves the back and forth of argument moving from one thing known to another, and advancing in knowledge by such movement. Thus, for Thomas, while angels and God can be said to be intelligent, they are not rational.”

“Reason does not distinguish us from animals; it distinguishes us as animals. So according to Aquinas, while it is true that the activities of intellect and will are not the actualities of any physical organs, they are nonetheless the activities of the living human animal. It is Socrates the animal who knows and wills, not his mind interacting with his body.”

If acting knowingly and willingly has the plain ordinary meaning it does in the discussions of responsibility in Aristotle’s Nicomachean Ethics, I could fully subscribe to each individual statement in the last two paragraphs. This has no fancy metaphysical prerequisites. But a premise about acting knowingly and willingly does not seem to me to justify a conclusion about the activities of knowing and willing as such. Nor do I think that knowing and willing is the proper activity of Aristotelian nous or “intellect”.

(I think even Averroes would agree that it is Socrates the animal who “knows and wills”, in the sense that those terms have in Aristotle’s ethics. I think he would like the distinction between intellect and the reason of the rational animal. But I think Averroes would go on to specify that knowing and willing and rationality attach to the animal by way of a development of the animal’s “imagination”. I would myself also emphasize the role of language and ethos.)

I am not sure about calling intellect an operation “of the soul itself”, or indeed an “operation” at all. But I truly have no idea what an “act of existence” would be in Aristotelian terms. Plotinus spoke of the natural act of a being as its good. But “act of existence” to my ear suggests something more like Spinoza’s conatus or effort to exist, which seems at least in part to have a Stoic heritage. Neither of these meanings seems applicable to God. But then, neither is it yet clear to me how the “act of existence” of a created being is related to Aquinas’ notion of the pure act of pure Being, which I have understood as conferring the existence of beings.

A “Mind-Soul Problem”?

Still slowly making my way through volume 3 part 1 of Alain de Libera’s Archéologie du sujet, I’ve passed through a section in which he raises the question of a “mind-soul problem”. In the wake of Descartes’ mind/body dualism, many modern authors have spoken of a “mind-body problem”, and proposed materialist or spiritualist alternatives to the dualism of Descartes. Hardly anyone in modern times has addressed a “mind-soul problem”.

My own usage of “soul” is intended purely as a translation of what Aristotle called psyche. I usually avoid “mind”, which has a heritage going back to Augustine’s mens, but has come to be widely used both for everything in the sphere of conscious awareness and for the object studied by modern psychology. Modern philosophers may speak of a philosophy of mind, but what is mind, really? In French and German, the word for spirit takes the place of the English “mind”.

The medieval term “intellect” (a translation of Aristotle’s nous) has much more specific connotations than any of these, though it might be argued that the role Aquinas gave it relative to underwriting the soul’s immortality played an important role in the emergence of modern notions of mind or spirit as something assumed to be a relatively uniform singular thing. Mind in Augustine does seem to have a kind of simplicity also, though Augustine’s soul/body dualism was very different from Aquinas’ combination of Aristotelian hylomorphism with his own non-Aristotelian metaphysical notion of intellectual soul.

De Libera points out that numerous medieval authors discussed the contrast between intellectio (thought, concerned with universals) and cogitatio (the soul’s awareness, concerned with particulars and grounded in what was called imagination). I like to read the discourse about intellect as pointing toward what Kant would later call transcendental considerations, whereas cogitation would belong to the empirical domain.

The common translation of Descartes’ cogito as “I think” confusingly crosses this boundary. The “I” part has also been questioned by various authors, but clearly Descartes was talking about a concrete awareness informed by many particulars, although he gave it a privileged metaphysical status. Locke’s Essay Concerning Human Understanding was certainly also concerned with concrete, empirical awareness, but when he had it translated to Latin, the Latin for “intellect” was used to render “understanding”.

As de Libera says, the “mind-soul problem” is concerned with questions like whether the being that has awareness of sensation is the same as the being that thinks. I imagine that there is a kind of sharing, overlap, and community between the two, but not an identity. Many ancient cultures East and West saw distinctions in this area, where most of the Latin Scholastics and Western modernity insisted on an overarching strong unity or formal uniformity of the “intellectual soul” or mind.

And again, what is thinking?

Speaking in the common way, “I think” that thinking is something more profound than the action of an ego. It’s not at all clear to me that it is entirely “mine”; I tend to think the contrary. And I think there is a big element of receptivity in the apprehension of reality. I don’t mean that anything is just handed to us ready-made, but I think it is equally wrong to say that we make it all. What’s interesting to me is the region in between. Thinking has an active component, but it is not simply an “action”. Models for action include creation from nothing and mechanical impulse; neither of these seems to me like a good analogy for thought. Activity is much wider than action.

“The Subject” in Medieval Times

According to Alain de Libera in the second half of Archéologie du sujet vol. 1, Thomas Aquinas was instrumental in developing a view of the soul that was neither Aristotelian nor Augustinian, and that paved the way for the modern concept of “the subject” as an agent, long before Descartes. De Libera says that Aquinas did this in part by introducing the different, very abstract Aristotelian notion of subject (hypokeimenon, “thing underlying”, with no connotations of mind or agency) into the Augustinian model of the soul as an image of the Christian Trinity, and simultaneously introducing the Augustinian biblical Word into an Aristotelian model of abstractive knowledge. Aquinas also drew indirectly on Plotinus, and directly on his teacher Albert the Great’s use of pseudo-Dionysius. In doing so, he effectively removed the stigma Augustine had placed on treating the human soul as a “subject”.

Aristotle had suggested that there is a kind of identity between thinking and what it thinks. It is perhaps not accidental that we use different senses of the same English word “thought” for both. These should not be equated with subject and object in the modern sense; they both occupy parts of a kind of middle ground between what we call subject and object.

According to de Libera, Plotinus developed a kind of identity between three terms (nous, noeisis, noeton — intellect, intellection, intelligible object). His intellect and intelligible object are already somewhat closer to what we call subject and object. In between, he placed an act of thinking or intellection that was to have a kind of identity with both the intellect and the intelligible object.

Plotinus’ notion of act is also quite different from that of Aristotle. Aristotle calls the first principle a kind of pure act that is not an action in the ordinary sense, and has nothing else behind it; for Plotinus, the first principle is a power, and every act is the act of a power. For Aristotle, the first principle is also an end only; for Plotinus, it is both the end and the origin of all things.

The persons of the Trinity are supposed to have a sort of mutual immanence to one another that is completely unlike the case of something underlying something else. De Libera notes that Plotinus and his student Porphyry already used a similar concept of mutual immanence in their discussions of intellect. Augustine ranked his reading of Plotinus as a formative experience second only to his conversion to Christianity.

From the Christian neoplatonist pseudo-Dionysius, Albert the Great drew the notion of a “whole of powers” that is different from either a universal whole or an integral whole.

De Libera notes that the classic formula of the Trinity in Greek — one ousia, three hypostases — was confusingly translated into Latin as “one essence, three substances” or as “one substance, three persons”. By substitution, the coexistence of these two translations yields the obviously self-contradictory formula, “one substance, three substances”, which graphically illustrates the equivocation in medieval usages of “substance”.

(In deference to common usage, I have continued to use “substance” for Aristotle’s ousia, even though I think it is a terrible translation. “Essence” is better, provided we recognize that Plato and Aristotle had views of essence that were not “essentialist” in the sense of treating essences of things as pre-given or as something to take for granted.)

De Libera speaks of the need to parenthesize modern notions of subject and object in order to understand Augustine’s opposition to treating actions and passions of the soul as attributes of a substance. Conversely, for better or worse, Aquinas’ legitimation of this way of viewing the soul brings us closer to modern views. (I think Aristotle would have shared Augustine’s opposition to this formulation, but for different reasons. I think Aristotle regarded the whole human being — and not the soul or the body taken separately — as a “substance”.)

Aquinas introduced emphasis on both what de Libera calls an Aristotelian structure of subject-powers-activities and a pseudo-Dionysian structure of essence-power-operation into a Latin-speaking theological context that had been mainly dominated by Augustine. What I would call this double infusion of additional neoplatonic elements is said by some to have resulted in a more dynamic and relational way of viewing things. (In agreement with Gwenaëlle Aubry, however, I think Aristotelian potentiality is very different from neoplatonic power, even though they use the same Greek word.) Combined with Aquinas’ serious embrace of a version of Aristotelian hylomorphism, this infusion led to a simultaneously more positive and more dynamic view of worldly existence than had been common in the Augustinian tradition, which also helped lay the seeds of modernity.

A broadly neoplatonic view of the world in terms of powers and operations-of-powers thus turns out to have been very important for the emergence of the modern subject-as-agent (as well as, I would argue, the rise of the specific modern notion of causality). De Libera notes that Heidegger ignored both neoplatonism and theology in his famous account of the rise of the modern subject. Meanwhile, Aquinas’ legitimation of the treatment of actions and passions as attributes of a soul-subject-substance — coupled with the interweaving of such attribution with imputations of responsibility — seems to have contributed to a stronger notion of a self as something with univocal identity and sharp edges.

Origins of a Subject-Agent

How did the modern equation of subjecthood and agency come to be? How did the notion of “I” or ego come to be substantialized? An extremely influential argument of Heidegger makes this an innovation of Descartes. Alain de Libera argues that this is too hasty, and that the groundwork for this identification was actually laid in the later middle ages. I’m continuing a high-level treatment of de Libera’s extremely important archaeology of the subject (see also On a Philosophical Grammar).

Answering this question will involve an extended historical odyssey through complex interactions between Aristotelian and Augustinian views, and much more. De Libera sees Aquinas in his polemic against Averroes raising four interrelated questions of a more fundamental nature: Who thinks? What is the subject of thought? Who are we? What is man? The second of these seems to have been first asked by Averroes. The other three are largely attributable to Aquinas and his contemporaries, in their reactions to Averroes.

Several points of Aristotelian interpretation (What is substance? What is form? What is act? What is an efficient cause? What is the soul?) will be relevant to answering these, as will Augustine’s meditations on personhood and the nature of the Trinity. De Libera notes that John Locke — a major contributor to modern views on “the subject” — was deeply involved in debates on trinitarian theology. He also discusses Franz Brentano’s modern revival of the medieval notion of intentionality. The medieval version was closely bound up with a notion of “inexistence” or “existing in” of mental objects (forms separated from their matter) in the soul.

In the Categories, Aristotle gives substance the logical sense of something standing under something else. This influenced the Greek grammarians who formulated the notion of a grammatical subject. But in the Metaphysics, he treats this as only a starting point that is quickly superseded by an identification of substance with form or “what it was to have been” a thing, before moving into an account of substance as potentiality and actuality.

De Libera notes a historic division among readers of Aristotle’s treatise On the Soul between those who interpret the soul as an attribute of the body, and those who treat it as a substance in its own right. The latter position has different meanings, depending on whether substance is taken in the “standing under” sense or in the sense of form. De Libera will be particularly interested in the consequences of a further family of positions that make the non-obvious equation of human actions and passions with attributes of the soul.

He notes that “category” in Greek originally meant accusation, and relates this to Locke’s characterization of personhood as a “forensic” notion. We have here to do with subtle relations between attribution, inherence, and imputation with respect to actions and passions in relation to the soul. But what is an action? Must we explain an act in terms of a substantial subject’s power of efficient causation in a late scholastic sense that is far from Aristotle’s? (See also Expansive Agency; Brandomian Forgiveness.)

On a Philosophical Grammar

It seems like a good time to get back to a bit more detail on Alain de Libera’s “archaeology of the subject”, which I introduced a while back. Volume 1 is subtitled Naissance du sujet or “Birth of the Subject”. He begins with a series of questions asked by Vincent Descombes in a review of Paul Ricoeur’s Oneself as Another:

“1) What remarkable differences are there, from the point of view of use, between these words which we place too lazily in a single category of personal pronouns (and particularly here I, he, me, him, her, oneself)?

“2) What is the status of intentions to act? Are they first properties of the agent?

“3) Should we distinguish, as Ricoeur proposes, two concepts of identity, identity as sameness (idem) and identity as ipseity [“selfness”] (ipse)?

“4) What is this self that figures in the expression self-awareness?” (Archéologie du sujet vol. 1, p. 31).

The birth of the subject in the modern sense is what de Libera will investigate. He aims to show how “the Aristotelian ‘subject’ [hypokeimenon, or thing standing under] became the subject-agent of the moderns in becoming a kind of substrate for acts and operations” (p. 39). He quotes a famous passage from Nietzsche denouncing the “grammatical superstition” of the logicians who assume that wherever there is a predicate for an activity such as thinking, there must be something corresponding to a grammatical subject that performs it. Nietzsche says that a thought comes when it wants, not when I want.

De Libera asks, “How did the thinking subject, or if one prefers, man as subject and agent of thought, first enter into philosophy? And why?” (pp. 45-46). He points out the simple fact that a grammatical subject need not be an agent, as when we say “the boy’s timidity made him afraid”. He quotes Frédéric Nef to the effect that action is not a grammatical category. How then did “the subject” become bound up with agency?

He notes that something like this is already at play in Aquinas’ Disputed Questions on the Soul, when Aquinas develops the notion of a “subject of operation” related to sensibility, associating the subject of an action or passion with a power of the soul. How, de Libera asks, did we come to assume that every action requires “an agent that is a subject” and “a subject that is its agent” (p. 58)? (See also Not Power and Action.)

He will be looking for medieval roots of notions that most people, following Heidegger, consider to be innovations of Descartes. Meanwhile, de Libera recalls that Augustine had gone so far as to label it blasphemy to call the soul a “subject”. Knowledge and love, Augustine said, are not in the mind as in a subject.

“This Human”, Again

Stephen Ogden’s Averroes on Intellect (2022) is the first book-length treatment of this fascinating subject of medieval controversy that is centrally focused on an independent philosophical evaluation of the arguments of Averroes himself. Ogden develops a reading of Averroes in close relation both to the Aristotelian text and to the contrasting positions of Avicenna and Aquinas. Averroes, he says, deserves to be taken seriously both as a reader of Aristotle and as a philosopher in his own right. Averroes challenges us to question our assumptions as to what “intellect” might be.

Ultimately, Ogden suggests a sort of compromise between Averroes and Aquinas. This makes an interesting counterpoint to the interpretation of Deborah Black.

Like Black, Ogden highlights the common ground between Averroes and Aquinas. He develops the fact that unlike most earlier commentators on Aristotle, Averroes and Aquinas both explained actual and potential “intellect” in symmetrical ways that made them the same broad kind of being. They also both distinguished a third, “passive” intellect — said to be a kind of disposition of the human imagination — that others have often identified with the potential intellect.

Prior to Averroes, the most common type of reading made actual intellect a singular or universal cosmic or metaphysical principle, while treating potential intellect as something mortal and divided among many individuals. (While fascinating, this is to my mind anomalous with respect to the way Aristotle himself develops the relations between potentiality and actuality. I tend to think of these as only analytically distinguishable aspects, phases, or modes of the same real things.)

Averroes and Aquinas agree that both actual and potential “intellect” are immaterial things that are not dependent on the body. They both defend variants of what is termed “moderate realism” with respect to universals. In this kind of view, universals have reality independent of particulars, but they do not subsist in themselves as Plato thought. They are “abstracted” from human imagination by something called “intellect”.

On the other hand, Aquinas and Averroes approach the interpretation of “intellect” with very different concerns in mind. Ogden agrees with Deborah Black’s point that the role of intellect for Averroes lies in the constitution of intelligible objects. Further, for Averroes the universal singularity of “intellect” carries the whole burden of underwriting a non-Platonic reality of universals as universals.

For Aquinas on the other hand, I would say the primary role of intellect is to underwrite a metaphysically strong notion of personal identity. Aquinas uses a complex original theory of intelligible “species” to do most of the work of underwriting the reality of universals. This leaves him free to repurpose “intellect” as a basis of a philosophical argument for personal immortality that has no parallel in Averroes or Aristotle. Aquinas develops a nuanced account of how the soul exists in genuine union with the body, but each individual soul contains within it intellect that is separable from body. For Aquinas, the presence of intellect within the soul guarantees the immortality of the soul. Ogden mentions in passing Aquinas’ acceptance of Aristotle’s view that memory, however, is inseparable from the body.

Ogden agrees with Black that Averroes successfully explains the experience of human self-awareness in terms of imagination, without needing to appeal to intellect. But Ogden says that for Averroes, in a stricter sense it is indeed only the intellect as our perfective form that “understands”, so perhaps we should say that thought happens within us, rather than that we think.

He mentions that Bertrand Russell said that Descartes should have said “there is thought”, rather than “I think”. I would add that “I” am not a “thinking thing”, but an ethical being constituted by my commitments and practices of commitment.

“This Human Understands”

Imagination rather than intellect is actually the main locus of human consciousness for both Thomas Aquinas and the great Aristotelian commentator Averroes whom Aquinas famously criticized, according to medieval scholar Deborah Black.

“[W]ithin the Aristotelian framework which Aquinas and Averroes share, the psychological explanation and interpretation of intellectual consciousness is not itself a given, even if the experience of consciousness is. Consciousness of thinking may play a central role in Cartesian philosophy, and in the system of Averroes’s and Aquinas’s predecessor, Avicenna. But it has no such privileged status in the philosophies of Aristotle, Averroes, or Aquinas, in which the possible intellect ‘is actually nothing before it thinks,’ and is only able to think itself after it has been actualized by some other object”, she wrote in her 1993 essay “Consciousness and Self-Knowledge in Aquinas’s Critique of Averroes’s Psychology”.

The relation of so-called “intellect” (nous) to the human “soul” (psyche) in Aristotle has historically been a major point of contention. These words are used in subtly or extremely different ways by many authors. I strongly recommend holding off on any easy identification of either of them with what modern people think of as subjective mind or consciousness.

Aristotle seems to apply a variant of his fruitful pairing of potentiality and actuality in his rather minimalist account of intellect. These notions were developed in greater detail in the commentary tradition. To hazard an oversimplification, intellect in actuality was considered to be something immaterial that makes things intelligible, whereas intellect in potentiality was considered to be something with no form of its own that takes on intelligible forms.

The great Greek commentator Alexander of Aphrodisias identified the potential or “material” intellect with a part of the soul, which he considered to be inseparable from the body, and therefore mortal. The actual or “agent” intellect he identified with a divine principle that he also gave a cosmological role.

The brilliant Arabic commentator Averroes (Ibn Rushd) argued that both aspects of intellect were symmetrically unique immaterial principles, outside the soul but connected with it. He became convinced that all humans must share a common “material” (potential) intellect, which grounds the real existence of logical universals and intelligible forms, but gets its contents from human imagination, and would not exist if there were no rational animals.

Aquinas located both intellects within the human soul, while giving the latter the elevated, more neoplatonic metaphysical status of an “intellectual soul”, and strongly associating its intellectual character with personal immortality. Especially in later works, Aquinas polemicized sharply against Averroes, claiming that Averroes could not even consistently say that “this human understands”, because for Averroes in his Long Commentary on the De Anima, there is only one material intellect shared by all humans.

Deborah Black argues that the two phases of intellect in Aristotle work together to constitute objects and intelligible forms. This need not imply an experience of immediate self-awareness. For Aristotle, Averroes, and Aquinas, intellectual self-awareness emerges only indirectly.

Black points out that Aquinas typically uses words like “perceives” or “experiences” in talking about self-awareness, and seems to deliberately avoid words implying intellectual comprehension. She sees this as reflecting Aristotelian scruples, and notes the studied vagueness of Aquinas’ endorsement of Augustinian immediate self-awareness. In his refutation of Averroes, Aquinas does appeal to the experience of consciousness, but she notes that he does so initially to argue against Plato’s identification of human being solely with intellect, pointing out that the same person perceives herself both to understand and to sense. “This human understands” does not actually emphasize any deep reflexivity, only individuality.

Aquinas approves of the fact that for Averroes, intellect is in some way united with the body, but argues that because for Averroes that union occurs only through a working of intellect on the contents of imagination, the human individual for Averroes does not herself think. On the other hand, Black argues that Aquinas does not take into account the fact that although what Aquinas himself calls imagination is an entirely passive reception of images, the contents of imagination for Averroes have a much more active character. For Averroes, according to Black, it is the active character of the contents of imagination that manifests human self-awareness. Because Aquinas views imagination as entirely passive, he refuses to acknowledge any credibility to this at all, claiming that the contents of imagination Averroes appeals to are really nothing more than the equivalent of inert colors on an inert wall, and that this makes the human equivalent to a wall.

Averroes compares active intellect to light, and so-called “material” intellect to a transparent medium such as air. Aquinas makes it sound as though the material intellect for Averroes would be analogous to the eye, which would make the material intellect a sort of mind behind our minds. However, Black says Averroes always compared it to a transparent medium, not to the eye. She argues that neither of Averroes’ intellects is a mind or a knower or subject in the modern sense. In her 2004 essay “Models of the Mind: Metaphysical Presuppositions of the Averroist and Thomistic Accounts of Intellection”, she contends that for Averroes, far from being the mind behind our minds that would make us into mere puppets, the material intellect serves as a shared instrument for human agents who individually constitute themselves in imagination.

Averroes’ notion of intellect, Black suggests, is mainly concerned with the constitution of intelligible objects as universals from imaginative content. It does not act as a subject in the modern sense. She cites a number of passages from Aquinas indicating that he, too, often treated intellect as an instrument, rather than as our very essence. (See also Parts of the Soul; Aristotelian Subjectivity Revisited.)

Ideas Are Not Inert

In the British empiricist tradition, “ideas” are supposed to be inert contents of an active “mind”, and to be either identical with sensible contents or derived from sensory experience. They are supposed to have content that just “is what it is”, but is nonetheless sufficient to serve as a basis for our conclusions and motivations.

I want to argue instead that the only possible basis for our conclusions and motivations is other conclusions and motivations. As individuals we always start in the middle, with some already existing conclusions and motivations that were not necessarily individually ours to begin with. Language and culture and upbringing provide us with a stock of pre-existing conclusions and particularly shaped motivations.

Further, I don’t see ideas as inert. The notion that ideas are completely inert comes from an extreme polarization between active mind and passive idea that results from entirely subordinating this relation to the grammatical model of subject and predicate. Aristotle’s rather minimalist account of these matters effectively treats objects and ideas as having some activity of their own. For Aristotle, “we” do not hold a monopoly on activity. There is also activity in the world that is independent of us, and much of our activity is our particular reflection of the world’s activity. Indeed for Aristotle I take it to be thought rather than an assumed “thinker” that is primarily active.

Hegel has often been criticized for speaking as if “the Idea” had life of its own, independent of us humans. If one holds an empiricist view of ideas, this can only sound like nonsense, or some kind of animism. But with an Aristotelian view of thoughts as a kind of intrinsically active “contents”, that is not the case. If thoughts are intrinsically active, we need not posit a separate mental “subject” distinct from any actual thought or perception or content as the source of all activity, behind thought.

Plato compared the human soul to a city — a kind of unity to be sure, but a weak one consisting of a federated community and relatively specific “culture” of thoughts and perceptions, subject to varying degrees of coherence. Only under the influence of later theology did it come to be assumed that the soul must necessarily have the far stronger unity of a simple substance. A looser unity of the soul is very compatible with a view of thoughts and perceptions as multiple fibers of activity, from which the overall activity we attribute to the soul or mind is constituted.