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 But in the Metaphysics, he treats this as only a starting point that is quickly superseded by an identification of substance with form or “what it was to have been” a thing, before moving into an account of substance as potentiality and actuality.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.)

Next in this series: “The Subject” in Medieval Times

“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.

Averroes

The Andalusian Arab Ibn Rushd (1126-1198 CE), known to the Latins as Averroes, was the most highly regarded commentator on Aristotle in the medieval and Renaissance Latin- and Hebrew-speaking worlds. Many of Aristotle’s central works first became available in Latin due to the translation of commentaries by Averroes that included Aristotle’s full text. In the early 14th century, the pope directed that European universities should teach Aristotle from the commentaries of Averroes, except where the opinions of “the Commentator” contradicted Christian faith. The first printed editions of Aristotle in the Renaissance were actually editions of Averroes with the works of Aristotle embedded in them.

Averroes was an Islamic judge in the Maliki tradition, and also an important medical authority. He maintained that philosophy and Islam taught the same truth in different ways. In addition to commentaries on Aristotle and works on law and medicine, he wrote several works on religion, and a short commentary on Plato’s Republic. The voluntaristic Sunni theologian al-Ghazali had written an influential denunciation of philosophy, which Averroes famously refuted in his Incoherence of the Incoherence. For most of his life he enjoyed the patronage of the Almohad caliphate, which controlled southern Spain and northwest Africa, but the situation was tenuous. Further East, the the Islamic Golden Age’s marvelous flowering of all sorts of learning and popular interest in “ancient wisdom” had already passed, as religious conservatives acquired greater influence.

As a reader of Aristotle, Averroes contributed greatly to distinguishing Aristotle’s own thought from that of the neoplatonically influenced commentary tradition. Though he only had access to Arabic translations of Syriac translations of the Greek, he did an amazing job of close textual analysis, comparing different translations of the same work to get better insight. He still inherited al-Farabi’s over-emphasis on demonstrative “science”, underestimation of the place of dialectic in Aristotle’s thought, and privileging of theory over practical ethical judgment, but on countless other points promoted textually sound and interesting readings of Aristotle’s works.

I feel a little guilty for perpetuating the Western obsession with a very narrow if important strand of his thought, concerned with his unique views on the nature of “intellect”, but I don’t read Arabic and my Latin is very poor, so my acquaintance is mainly based on sources in modern European languages. I also find the whole debate about intellect fascinating in its own right. (See also “This Human Understands”; “This Human”, Again; Averroes as Read by de Libera; Fortunes of Aristotle; Errors of the Philosophers; 1277.)

“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.)

Commitment to Commitment

A commitment to the practices associated with commitment is more fundamental than any particular commitment we may have. To say it another way, taking our committedness seriously is more important than the exact content of our particular commitments as to what is good and true, or to what we will do.

A high level of seriousness about commitments does not mean sticking to our guns at all cost. If we truly take our commitments seriously, that ought to mean that we also want to improve them when we have the opportunity, and to fix them when they are broken.

The American transcendentalist Ralph Waldo Emerson (1803-1882) famously made the remark that “a foolish consistency is the hobgoblin of little minds…. With consistency a great soul has simply nothing to do”. One might hope that he really meant to distinguish between a foolish consistency and a wise one — between a kind of rigid adherence to mere formalisms, and what I might call consistency in substance or essence or deep meaning. The latter would be more akin to personal integrity.

Emerson himself was a bit intemperate in the passage that followed (“Speak what you think now in hard words, and tomorrow speak what tomorrow thinks in hard words again, though it contradict every thing you said today”). He further confuses the matter by connecting this message with the theme that “great souls are always misunderstood”. This is all in his essay “Self-Reliance”. The rhetoric is quite memorable and there is a sense in which each of these sayings has validity, but they are both what Hegel would call “one-sided” formulations that are highly vulnerable to misuse. Their combination suggests the dangerous implication that it must be our fault if we don’t understand the one who says contradictory things. This clearly goes too far.

In the course of arguing that it is actually possible for a human to have a kind of general knowledge of being, Aristotle in Metaphysics book IV chapter 3 famously defends a principle of noncontradiction that is not merely formal.

He says in part, “For that which is necessary for one who understands any of the beings whatever to have is not a hypothesis” (Sachs translation, p. 58).

“[W]hat it is, after this prelude, let us state. It is not possible for the same thing at the same time both to belong and not to belong to the same thing in the same respect (and as many other things as we ought to specify in addition for the sake of logical difficulties, let them have been specified in addition). And this is the most certain of principles” (p. 59).

“[T]he starting point… is not the demand that one say something either to be or not to be (for perhaps one might suppose that this would require from the outset the things to be shown), but that what he says must mean something to both himself and someone else; for this is necessary, if he is going to say anything” (p. 60).

Robert Brandom argues that all the most important and valuable parts of Kant’s thought can be reconstructed in terms of the process of synthesizing a unity of apperception. This process is not a sequence of events that happen in the world; it is an ethical task for which we are responsible.

No truths follow from the principle of noncontradiction alone. In particular, it is not a deductive source of metaphysical conclusions.

On the other hand, it is what in Kantian language might be called a moral imperative. To be committed to commitment, I would argue, is to embrace that imperative. Stubborn persistence in self-contradiction destroys the possibility of shareable meaning and dialogue. In real life, self-contradiction happens to good people, but that should be an occasion for learning and humility, never something to proudly affirm.

As soon as we acknowledge piecemeal responsibility for the integrity of our commitments, we implicitly have responsibility for the integrity of the whole constituted by all our commitments. Commitment to commitment is an implicit condition of all our particular commitments, and it involves a responsibility for safeguarding and improving the integrity of the whole of our commitments. However fallible it may be, by its very nature it involves at least the germ of the crucial ability to learn, to improve itself and to correct itself.

This also has important consequences for what Kantian respect for others and the related notion of Hegelian mutual recognition look like in practice. First and foremost, respect for others takes the form of recognition of their implicit commitment to commitment, even when we do not endorse all the others’ particular commitments. (See also Brandomian Forgiveness.)

Predication

It is extremely common to see references to “predication” as if it were a central concept of Aristotelian logic. We are so used to a grammatical interpretation in terms of relations between subjects and predicates that it is hard to disengage from that. However, historically it was Aristotelian logic that influenced ancient Greek accounts of grammar, not vice versa.

Modern logicians distinguish between a neutral proposition — which might be merely mentioned, rather than asserted — and the assertion of the proposition. Grammatical predication in itself does not imply any logical assertion, only a normatively neutral syntactic relation between sentence components. But “said of” in Aristotle always refers to some kind of meaningful assertion that has a normative character, not to grammatical predication.

Aristotle talks about what we might call kinds of “sayables” (“categories”). He famously says that we can only have truth or falsity when one kind of sayable is “said of” another. Mere words or phrases by themselves don’t assert anything, and hence cannot be true or false; for that we need what modern writers have referred to as a “complete thought”.

The ordinary meaning of “to categorize” in ancient Greek was “to accuse in a court of law”. Aristotle used it to talk about assertions. It didn’t originally connote a classification. The modern connotation of classification seems to stem from the accident that independent of what “category” meant in his usage, Aristotle famously developed a classification of “categories”.

Aristotle also talks about logical “judgment” (apophansis, a different word from practical judgment or phronesis). Husserl for instance transliterated this to German, and followed the traditional association of logical judgment with “predication”. But the ordinary Greek verb apophainein just means to show or make known. Aristotle’s usage suggests a kind of definite assertion or expressive clarification related to demonstration, which makes sense, because demonstrations work by interrelating logical judgments.

All of Aristotle’s words and phrases that get translated with connotations of “predication” actually have to do with normative logical assertion, not any connecting of a grammatical subject with a grammatical predicate. Nietzsche and others have complained about the metaphysical status foisted on grammatical subjects, implicitly blaming Aristotle, but all these connotations are of later date.

The great 20th century scholar of ancient and medieval logic and semantics L. M. de Rijk in his Aristotle: Semantics and Ontology (2002) argued at length that Aristotle’s logical “is” and “is not” should be understood as not as binary operators connecting subjects and predicates, but as unary operators of assertion and negation on whole propositions formed from pairs of terms. (See also Aristotelian Propositions.)

As in similar cases, by no means do I wish to suggest that all the work done on the basis of the common translation of “predication” is valueless; far from it. But I think we can get additional clarity by carefully distinguishing the views and modes of expression of Aristotle himself from those of later commentators and logicians, and I think Aristotle’s own more unique perspectives are far fresher and more interesting than even good traditional readings would allow.

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.

Hume on Causes

The great British empiricist philosopher David Hume (1711-1776) wrote that “There are no ideas which occur in metaphysics more obscure and uncertain than those of ‘power’, ‘force’, ‘energy’, or ‘necessary connection'” (An Inquiry Concerning Human Understanding, Library of Liberal Arts ed., p. 73).

Hume is most famous for his critique of naive or dogmatic assumptions about causality. “[T]here is not, in any particular instance of cause and effect, anything which can suggest the idea of power and necessary connection” (p. 75). To me, it seems to be the idea of an underlying power or force responsible for causality that he is mainly questioning. He has no doubt that we continually experience instances of cause and effect.

“[There is] no such thing as chance in the world” (p. 69). “[T]he conjunction between motives and voluntary actions is as regular and uniform as that between the cause and effect in any part of nature” (p. 98). Clearly, then, he did believe in the reality of cause and effect, but only wanted to reject naive claims about our knowledge of the world that purport to link experienced instances of cause and effect to explanations in terms of the operation of underlying powers. What we actually experience in these cases is just lawful regularity.

“It is certain that the easy and obvious philosophy will always, with the generality of mankind, have the preference above the accurate and abstruse…. The fame of Cicero flourishes at present, but that of Aristotle is utterly decayed” (pp. 16-17). But on the other hand, “All polite letters are nothing but pictures of human life in various attitudes and situations…. An artist must be better qualified to succeed in this undertaking who, besides a delicate taste and a quick apprehension, possesses an accurate knowledge of the internal fabric, the operations of the understanding, the workings of the passions…. However painful soever this inward search or inquiry may appear, it becomes in some manner requisite to those who would describe with success the obvious and outward appearances of life and manners…. Accuracy is, in every case, advantageous to beauty, and just reasoning to delicate sentiment. In vain would we exalt the one by depreciating the other” (p. 19). Clearly, then, Hume’s polemic against scholastic modes of reasoning does not at all mean he simply rejects the values of “accurate and abstruse” philosophy.

Neoplatonizing tendencies in the Aristotelian commentary tradition led to the common Latin scholastic view of causes as metaphysical powers operating behind the scenes that Hume is mainly concerned to criticize. Aristotle himself identified causes more broadly and much less speculatively with every kind of “reasons why” things are as they are and behave as they do. He did so without making extravagant claims to certain knowledge. Whereas scholastic philosophers characteristically debated the pros and cons of accepting various abstract propositions, Aristotle himself was fundamentally concerned with the use of reason to help interpret concrete human experience (see Aristotelian Causes).

Hume is a great philosopher, and so far I have focused on a positive appropriation of his work, having some points in common with themes I have been pursuing about causality and the notion of power. Robert Brandom’s innovative reading of Kant’s response to Hume points out that there are distinct limits to Hume’s approach.

“Kant read Hume’s practical and theoretical philosophies as raising variants of a single question. On the side of practical reasoning, Hume asks what our warrant is for moving from descriptions of how things are to prescriptions of how they ought to be. How can we rationally justify the move from ‘is’ to ‘ought’? On the side of theoretical reasoning, Hume asks what our warrant is for moving from descriptions of what in fact happens to characterizations of what must happen and what could not happen…. Hume’s predicament is that he finds that even his best understanding of facts doesn’t yield an understanding of either of the two sorts of rules governing and relating those facts, underwriting assessments of which of the things that actually happen (all he thought we can directly experience) ought to happen (are normatively necessary) or must happen (are naturally necessary).”

“Kant’s response to the proposed predicament is that we cannot be in the situation that Hume envisages: understanding matter-of-factual empirical claims perfectly well, but having no idea what is meant by modal or normative ones” (Brandom, Reason in Philosophy, p. 54).

Brandom continues, “To judge, claim, or believe that the cat is on the mat, one must have at least a minimal practical ability to sort material inferences in which that content is involved (as premise or conclusion) into good ones and bad ones, and to discriminate what is from what is not materially incompatible with it. Part of doing that is associating with those inferences ranges of counterfactual robustness…. So, for example, one must have such dispositions as to treat the cat’s being on the mat as compatible with a nearby tree being somewhat nearer, or the temperature a few degrees higher, but not with the sun being as close as the tree or the temperature being thousands of degrees higher. One must know such things as that the cat might chase a mouse or flee from a dog, but that the mat can do neither, and that the mat would remain essentially as it is if one jumped up and down on it or beat it with a stick, while the cat would not. It is not that there is any one of the counterfactual inferences I have mentioned that is necessary for understanding what it is for the cat to be on the mat. But if one makes no distinctions of this sort — treats the possibility of the cat’s jumping off the mat or yawning as on a par with is sprouting wings and starting to fly, or suddenly becoming microscopically small; does not at all distinguish between what can and cannot happen to the cat and what can and cannot happen to the mat — then one does not count as understanding the claim well enough to endorse it” (pp. 54-55).

Brandom concludes, “If that is right, then in being able to employ concepts such as cat and mat in ordinary empirical descriptive claims one already knows how to do everything one needs to know how to do in order to deploy concepts such as possible and necessary — albeit fallibly and imperfectly” (p. 55).

I am actually a little more sympathetic to Hume, in that I don’t read him as categorically rejecting the validity of concepts of necessity, only any possibility of certain knowledge of how they apply to the real world. I personally like the position of Leibnitz that necessity is real but always hypothetical, never categorical. But Brandom is right that Hume does not go on to emphasize how essential our fallible understanding of necessity is to our understanding of ordinary experience.

Mechanical Metaphors

Perhaps the greatest contribution of the Italian physicist, astronomer, and engineer Galileo Galilei (1564-1642) — regarded by many as the single most important originator of modern, mathematically oriented natural science — was a unified explanation of both astronomical and earthly phenomena by the same set of mathematical principles for analysis of the behavior of physical bodies and matter. This was a generalized mechanics of solid bodies.

The tremendous power of this new way of understanding the physical behavior of bodies is undeniable. At least until the computer age, it has been the main basis of modern engineering and technology.

A historical side effect of this immensely successful development has been the promotion of solid-body mechanics as a kind of privileged metaphor for causality in general. I’ve several times discussed the transformation of Aristotle’s notion of efficient cause (most fundamentally, the means to actualization of an end) into the very different notion of “driving” cause or “motor” by medieval and early modern authors (see Efficient Cause, Again; Suárez on Agents and Action; Effective vs “Driving”; Not Power and Action). In combination with a very un-Aristotelian tendency to reduce other causes to efficient causes, this created a ripe condition for the spread of a view of causality in general in terms of metaphors based on solid-body mechanics. We are now so used to this that it takes effort to imagine any other view.

But the solid-body interaction metaphor ultimately leads to an impoverished, overly narrow view of causality in general. (For an alternative, see Aristotelian Causes.) Even within mechanics proper, solid bodies are no longer the paradigmatic, privileged case. At scales that are too small or too large, analogies to the behavior of medium-sized solid bodies break down. In broader contexts, wave phenomena are as important as the analysis of solid bodies. The great Roman poet-physicist Lucretius already had the insight that in the general case, atoms in aggregate behave more like liquids than like solids.

Irreducible to any purely mechanical paradigm, disciplines like earth sciences, ecology, medicine, economics, and computer science provide many examples of more complex and subtle interactions and structures that suggest a new need for something more like an Aristotelian view of causality, as having more to do with forms of things than with force.

Time and Eternity

One of Kant’s innovations was a new analysis of the constitution of temporal experience. His famous theses about the role of synthesis in experience provide new insight into the paradoxes of temporal being or “becoming”, and its relation or non-relation to something outside of time. These had been raised by pre-Socratics like Heraclitus and Zeno of Elea, and more satisfactorily treated by Plato and Aristotle.

Heraclitus famously said that everything flows, you can’t step into the same river twice, and things change into their opposites. Zeno went in the opposite direction, conceiving space and time in terms of instants and points, neither of which have any magnitude. He then pointed out that motion at a durationless instant is a logical contradiction. On this basis, Zeno claimed to prove various things that violate common sense, such as that an arrow can’t fly, and that the speedy Achilles could never catch up with a turtle that had a head start. From this he concluded that motion, space, and time were mere illusions.

Plato seems to have at first focused on a sharp distinction between true “being” as eternal on the one hand, and becoming in time as mere appearance on the other. This distinction allowed him to have it both ways. But in dialogues that are thought to have been written later such as Theaetetus and The Sophist, he came to suggest that being and time are not simply two disjunct categories.

Aristotle made time and space more intelligible by developing notions of duration and extension. For Aristotle, duration and extension come first, while durationless instants, magnitudeless points, and pure flux are all abstractions. I see him as an early advocate of the primacy of process. For Aristotle, the key to making this viable is to be able to explain how becoming as we experience it is really not just a pure flux, but rather is full of islands of relative stability that allow us — contrary to Heraclitus — to reidentify objects as having an underlying basis of sameness that persists through various kinds of change. It turns out that the edges of the islands are not rigidly distinct, but he developed the notion conventionally translated as “substance” to explain our experience of the relatively persistent form of their middles.

It is here that Kant’s contribution is significant. Aristotle develops a plausible account of the persistence of form through change, but he discusses it mainly from the point of view of how things are, even though he separately suggests that experience is also shaped by processes of interpretation by us. Kant took up that suggestion, and developed it in considerable detail. Kant consistently emphasizes our role in constituting the stability of form of things we experience in time, though he also insists on an “empirical realism” that justifies most of what we get from so-called common sense. This implies that for Kant as well, there implicitly must be some basis in the way things are, for the stable constructs we come up with. Much of Hegel’s Phenomenology was devoted to a further development of these Kantian insights.

The neoplatonists and Augustine insisted that things in time have a source and destination in eternity. Classic neoplatonism attempted to treat this relation as a sort of quasi-logical unfolding of the divine essence, while Augustine identified it with the act of creation. The relation of temporal being to eternity remained a notorious point of difficulty in neoplatonism, while Augustine called it a mystery.

Hegel thought that Augustine ended up locating all reality in the Eternal, and that this resulted in a devaluation of actual life and experience. Aquinas already used ideas from Aristotle to allow for a more positive evaluation of temporal being. Some spiritual traditions go further and suggest that we humans have a sort of co-creator role in the world we experience. But it was Kant who mainly developed the basis for a non-supernatural explanation consonant with the spirit of this. The main point is that the world is not initially given in the form of pre-existing objects. We separate out objects from the sensible continuum, but at the same time this is not an arbitrary operation. We can’t just materialize a unicorn by thinking of one, but we do play a major active role in the construction of universals like “horse”, and in the recognition of persistent individuals.

Essences of things, once constituted, seem to “subsist” in some virtual way outside of time. The traditional view was that essences are straightforwardly built into the nature of things, or else simply dictated by God. Either way, this means that for us, they would be pre-given. I don’t think Aristotle really regards them this way, but only in the special case of biological organisms does he investigate their genealogy. Kant on the other hand effectively develops a generalized genealogy of essences, showing how they can be understood as temporally constituted.

Another of Kant’s big innovations is in explaining how we play a significant role in our own constitution. I think it is a grievous error to regard such processes of self-constitution as beginning with a blank slate, or as magically independent of real-world constraints, but there is a very important way in which we end up defining who we are — not by an explicit decision, but indirectly through the sum total of our commitments, actions, and responses to things.

That ethical “who we are”, while originating in time, is itself an essence with virtual subsistence. As with all essences, considered in its virtual subsistence, it is eternal. Aristotle would say that our essence stops evolving when our temporal being comes to an end. At that point, who we were is finally stabilized, as the total act of a life.