Summa I q.84 a.6: Does Our Knowledge Come from the Senses? Democritus, Plato, and Aristotle's Middle Way

Orientation #

He does not say what was done last time, apart from “as has been said before” for Plato’s separated forms and “we’ve talked about this before” for the truth-in-the-middle theme and for the question whether the way we know must be the way things are (prev. lecture, unresolved by the context block). He ends: “you want to take a little break?” The source-matcher also flags a handout on Metaphysics VI (Aquinas’s commentary, lectio 4), but nothing of that appears in this transcript; possibly it belongs to the portion after the break.

The class, in order #

1. Objection 1: Augustine, truth not from the bodily senses (“the sincerity of truth, Augustine says”) #

The point: Augustine’s 83 Questions says the sincerity of truth ought not to be expected from the senses of the body, and proves it two ways.

• Aside on the title: the 83 Questions is a bit like Thomas’s quodlibetales (“whatever you wish”), which lack the order of the quaestiones disputatae and cover whatever people happen to wonder about; Augustine’s probably has more unity of subject.
• Proof (a): everything the bodily sense attains is changing “without any intermission of time”; what does not remain cannot be perceived. He remarks Augustine “sounds almost like Heraclitus” and his followers, who said you can’t say anything because the thing changes before you finish.
  • Aside on sensing motion: do you actually see a skier’s motion coming down the mountain? You are not in two places on the hill at once, yet “we do sense it in a way”; motion “stretches our senses more than anything else.”
• Proof (b): even when sensibles are absent we undergo their images (asleep, or mad), and we cannot discern by sense which are false; nothing is perceived that is not discerned from the false.
• His comment: here you see “how much more of a Platonist than an Aristotelian Augustine is,” at least in his way of speaking, compared with Thomas.

2. Objections 2 and 3, and how Thomas will answer (“the lower would be what producing the higher”) #

• Obj. 2 (Augustine, Gen. ad litt. XII): no body makes something in the spirit; the spirit is not subject to the body as matter to a maker; everything that makes is more outstanding than that on which it works; so the spirit by itself makes the image of the body. Otherwise “the lower would be producing the higher.” Preview of the reply: Thomas will say the images are only a tool of the active reason acting on the reason that undergoes.
• Obj. 3: an effect does not exceed the power of its cause; but we understand things we do not sense, such as truth or God.
• His preview of the whole answer: the things we don’t sense we come to know naturally through the things we sense; the senses are not the complete and primary cause; that is the active intellect, which acts on the images and makes what is understandable in ability understandable in act.
• The order of our knowing, “you see this yourself”: sensing, then memory of what was sensed, then a collection of many memories of the same sort, called experience, then the active intellect separates out what the many singulars have in common. Example: mother says “see the dog” repeatedly; after a number of dogs the child separates out what they have in common, something universal, and that is the beginning of the knowledge of reason. Boethius: a thing is singular when sensed, remembered, even in experience; only when understood is it universal. Then one recognizes new instances (the dog lying on the rug when he came in). The chief cause of the universal, of its being actually separated from the singulars, is the act of understanding.

3. Sed contra and an aside on Thomas as student of Aristotle (“humble and faithful student of Aristotle”) #

The point: Aristotle proves in Metaphysics I that the beginning of our knowledge is from sense; the proem to wisdom treats sensing, memory, experience, and Thomas has something like it at the end of book I or start of book II of the Summa Contra Gentiles.

• Aside: a Summa text where Thomas gives three reasons no creature is its own goodness (its substance is not its existence; its goodness needs added accidents, e.g. the virtues; its end is other than itself), and a similar place in the De Veritate (which “should be called Quaestiones Disputatae de Veritate et de Bonitate,” since around question twenty it turns to the good) where he brings together Boethius, Augustine and Aristotle or the Liber de Causis; Cajetan’s remark that Thomas seems to have inherited the mind of all the Church Fathers because he so reverenced them, yet he had a great debt to Aristotle.

4. The body: Democritus and Plato as the two extremes (“there was a threefold opinion among the philosophers”) #

• Democritus: no cause of knowledge but the images that flow out of bodies and enter the soul (Augustine’s letter to Dioscorus; Aristotle, On Sleeping and Being Awake, “de fluxionibus”). Reason: he and the other ancient natural philosophers did not hold that understanding differs from sense (De anima); since sense is changed by the sensible, all knowledge comes by the change sensibles produce.
• Plato, “a contrario,” furthest away: understanding differs from sense and is an immaterial power not using a bodily organ; since the incorporeal cannot be changed by the bodily, intellectual knowledge comes by partaking of separated understandable forms (“ideas,” better “forms”).
• The question he raises: does truth lie in the middle between two extreme errors, as a synthesis of what is true in each?

5. Digression: truth lies between adding and subtracting (“the truth, the whole truth, and nothing but the truth”) #

The point: to say the truth is to say that what is, is, and what is not, is not; so there are two ways of being false.

1. Saying what is, is not: subtracting from the truth (“Berquist is not standing now”).
2. Saying what is not, is: adding to the truth (“Berquist is sitting now”).

• Billfold: forty dollars; “I’ve got sixty” adds, “I’ve only got twenty” subtracts.
• Shakespeare: Kent in King Lear, “all my reports go with the modest truth, nor more, nor clipped, but so”; note Shakespeare’s grammar says “nor … nor” and “or … or” where we say “neither … nor,” “either … or.” Falstaff: those who say more or less than the truth “are villains and the sons of darkness.”
• Courtroom oath: “the truth” = what is is, what is not is not; “the whole truth” = no subtracting; “nothing but the truth” = no adding. Bartender: John and Henry were at the bar between nine and ten; leaving one out says what was was not; adding Tom or Paul says who was not there was there.
• The sign of the cross touches Trinity and Incarnation, whose mysteries are reversed: one nature, three persons; one person, two natures. Heresies as adding and subtracting: in the Trinity, three persons so three natures (Arius, as he names it) adds; one nature so one person (Sabellius; he also says “like Eutyches says”) subtracts. In the Incarnation, two natures so two persons (Nestorius: not Mother of God but Mother of Christ) adds a human person; one person so one nature (“Word was really made into flesh or something”) subtracts a nature.
• A further sign that truth is in the middle: the middle explains the extremes, because it contains a part of the truth in each. The three-natures man shares the truth that there are three persons; the one-person man shares the truth that there is one nature. If the truth were one person and one nature, there would be “no part of the truth” and so “no basis for any probability” in the contrary positions; likewise for the Incarnation.
• Applied back: Plato derives reason’s knowledge entirely from the immaterial; Democritus takes the sensible as by itself sufficient; Aristotle says there is an immaterial power, the act of understanding, but the senses also play a role, which everybody experiences.
• Baroque music: with no formal music education he recognizes baroque when he hears it, might mix a Haydn with a Mozart but not a baroque piece with a Mozart, though he could not say distinctly what the baroque thing is; he has separated out something common.

6. Plato on sense, and Aristotle’s test for the soul’s separate operation (“Does the human soul have some operation or activity by itself”) #

• Plato on sense: sense too is a spiritual power operating by itself; sensibles change the organs, and the soul, aroused by that change, forms in itself the species of sensible things.
• Aristotle at the beginning of the De anima: whether the soul is immortal depends on whether it has an operation not in the body, because existence is presupposed to doing (“like Descartes said, I think therefore I am”: you have to be before you can do). If the soul’s being were only in the body, its doing would be only in the body; if it does something not in the body, its existence is not entirely immersed in the body.
• The three positions on this: the men before Plato, no operation not through the body (“the brain is the organ of thought”); Plato, senses and reason are of the soul alone; Aristotle in between: the intellect and will are not in the body, sensing and imagining are bodily. So both Plato and the early Greeks have an element of truth; Aristotle’s position “has the whole truth” divided among the others.
• Boethius, Consolation: Lady Wisdom appears with torn garments; the commentator says men grabbing for the truth have dismembered it, each taking a part and saying “I got the whole.” Empedocles had warned that we live briefly, amid miseries, see a part of the truth, and boast of having seen the whole, a form of pride. A man does not convince others unless he has seen some part of the truth; the danger is boasting of the whole.
• Augustine (Gen. ad litt. XII) seems to touch Plato’s opinion: the body does not sense, but the soul through the body, using it as a messenger to form in itself what is announced from outside. So for Plato neither intellectual nor sensible knowledge proceeds wholly from sensibles; sensibles arouse the sensible soul to sense, and the senses arouse the understanding soul to understand. He compares it to being reminded: what reminds you is not the source of what you recall. Meno: a surface that looks flat but has little indentations makes you recall the flat surface, as a picture of you reminds me of you.

7. Aristotle’s media via in the body of the article (“Aristotle went forward in the media via”) #

1. With Plato: understanding differs from sense.
2. Against Plato: sense has no operation without the communication of the body; sensing is an act of the conjunction (conjunctum) of soul and body, and so are all operations of the sensing part. Signs of the bodily nature of sensing: too bright a thing destroys the eye; kids going deaf next to the rock band; a too-strong taste prevents tasting afterwards; whereas thinking about God does not prevent thinking about lesser things but makes one more able, “for I exercise my mind.”
3. With Democritus: since sensibles outside the soul can cause something in the conjunction, the operations of the sensitive part are caused by the impression of sensibles on the senses; but not by an outflow, for Democritus held every action comes by the flowing out of atoms (De generatione). The main point he shares with Democritus: our senses sense because they have been acted upon by sensible things.
4. The understanding operates without communication of the body, and nothing bodily can impress itself on a bodiless thing; so for the intellectual operation the impression of sensibles does not suffice; something “more noble” is required. This answers objection 2. The italicised words quote De anima III: the agent intellect is more honourable than the one that undergoes; “that’s why we say it’s more divine to give than to receive.”
5. Not, as Plato held, from the impression of superior things alone; but the agent intellect makes the images (phantasmata) taken from the senses understandable in act by abstraction, separating out what they have in common; the singular as such is not understandable in act. Conclusion: from the side of the images the intellectual operation is caused by sense; but since images cannot change the possible understanding without being made understandable in act, sensible knowledge is not the whole and perfect cause but “more the matter of the cause” (“that’s interesting”). So there is an element of truth in Plato.

• Plato’s problem: he put what man, dog, cat, horse is by itself in an immaterial world, so what a man is would involve no matter, “obviously false.” Aristotle: these exist by themselves only in the understanding, separated from many images and memories; what is common to many exists as common only in the mind. Hence Albert the Great: the first thing considered in logic is the universal, what is said of many; we define man not Socrates, wisdom not the wisdom of Socrates.
• Student: say more about “more the matter of the cause.” Answer: matter is what the agent acts upon; the many images of dogs are that out of which reason, comparing them, abstracts what they have in common. The chief cause is the agent intellect, “the light which enlightens every man,” or a sharing of that light.

8. Reply to objection 1: knowing changing things changelessly (“Does what change is change?”) #

Thomas’s brief reply: truth is not to be wholly expected from the senses; the light of the agent intellect is required, through which we know truth in changeable things in an unchangeable way and discern them from their images.

• “Does what change is change?” The mind knows changing things in universal in a changeless way, so the way we know is not the way things are; but we don’t attribute the changelessness of our knowledge to the things. He calls this “the central question in philosophy”: does truth require that the way we know be the way things are? Is the definition of stupidity stupid, the definition of evil evil?
• Knowing vs loving: to know evil is good, to love evil is always bad, because love goes out to the thing in itself. Thomas: the love of God is better than the knowledge of God, since knowledge puts God into a mind inadequate to grasp him while love goes out to him in himself; but the knowledge of a stone is better than the love of stones; a fortiori the knowledge of evil is good and the love of evil is evil. Wisdom: we are shaped to what we love; the Old Testament: they became abominable like the things they loved. “If you love disgusting things, you are disgusting. If you know what is disgusting, that doesn’t make it disgusting.”

9. Reply to objection 2: Augustine speaks of imagination (“imagining is a motion made according to the sense”) #

• Augustine speaks not of the understanding but of the imagination; since for Plato imagining is of the soul alone, Augustine uses the same reason (agent more honourable than patient) to show that bodies do not impress their likenesses on the imagination, that Aristotle uses to prove the agent intellect separate. On Plato’s position one would need an active as well as a passive power in the imagination. If, with Aristotle, imagining is of the conjunction, no difficulty: the sensible body is more noble than the animal’s organ as act to potency, as colour in act to the pupil coloured in potency.
• Second answer: the first change of the imagination is through sensible things, because imagining is a motion made by the sense in act (De anima III). Look at me, close your eyes: the image persists. After an accident they take sworn testimony at once, because there is more agreement half an hour later than a month later. His boyhood game: look at a house a few seconds, close your eyes, and answer how many windows, whether there were shutters, their colour.
• But stored images can be twisted, divided and composed into things never sensed, the gold mountain, the fairy-tale glass mountain the horse tries to climb; there is an active aspect there, and Thomas allows an operation of the soul that forms diverse images even of things not taken from sense. Of this one can take Augustine’s words. This subsequent activity is what we now usually call imagination.
• Imagining is thus much like thinking: we form an image, we form a thought, unlike the senses’ direct knowledge of the thing. The English philosophers using “idea” mostly don’t know whether they mean a thought or an image; we too say “I think that’s so” and “I imagine that’s so” interchangeably.

10. Reply to objection 3 and close (“we have to know God by way of negation”) #

Sense knowledge is not the whole, nor even the chief, cause of intellectual knowledge, so it is no wonder it extends beyond the sensible; but we know those other things through sensibles. Hence we know God by negation, incorporeal, without parts, through what is a body and has parts. Not so in the beatific vision, which is not through the senses. “You want to take a little break?”

His words #

• “quodlibetales”: whatever you wish; questions on anything people wonder about.
• “sincerity of truth”: Augustine’s phrase for truth not to be expected from the bodily senses.
• “active intellect” / “acting upon understanding” / “agent intellect”: the power that makes what is understandable in ability understandable in act [ed.: intellectus agens].
• “reason that understands, reason undergoes”: the receiving intellect [ed.: possible intellect]; later “the undergoing, the possible understanding.”
• “experience”: a collection of many memories of the same sort of thing.
• “de fluxionibus”: Democritus’s knowledge by things flowing out of bodies.
• “a contrario”: Plato’s position as the contrary extreme.
• “media via”: Aristotle’s middle way.
• “conjunctum”: the conjunction of soul and body, subject of sensing.
• “phantasmata”: the Greek for images.
• “the matter of the cause”: images as that out of which the agent intellect makes something understandable in act.
• “the light which enlightens every man”: his gloss on the agent intellect.

Texts #

Read in class

• Thomas Aquinas, Summa Theologiae I, q. 84, a. 6, objections, sed contra, body, replies 1-3 (translated line by line). Mentioned
• Augustine, 83 Questions (obj. 1); De Genesi ad litteram XII (obj. 2, body); letter to Dioscorus (body).
• Thomas, Quaestiones quodlibetales (Marietti volume); Summa Contra Gentiles end of book I / book II; a Summa text on God as goodness itself; De Veritate around q. 20; Cajetan’s preface to the Summa.
• Aristotle, Metaphysics I (proem); De anima I (soul’s separate operation) and III (agent intellect more honourable; imagination a motion made by sense in act); On Sleeping and Being Awake; De generatione; Liber de Causis.
• Boethius (singular vs universal; Consolation of Philosophy, Lady Wisdom’s torn garments and the commentator).
• Plato, Meno; Empedocles; Heraclitus; Democritus; Albert the Great on the universal; Descartes.
• Shakespeare, King Lear (Kent), Falstaff; Wisdom and the Old Testament on becoming what we love.
• Flagged by the source-matcher but not present in this transcript: Aquinas, commentary on Metaphysics VI, lectio 4 (handout).

His questions #

• Do you actually see the skier’s motion coming down the hill? We do sense it in a way; motion stretches our senses more than anything.
• Does virtue lie in the middle, and does truth lie in the middle between two extreme errors? Yes, between an error that adds and one that subtracts, containing the part of truth in each.
• What two mysteries does the sign of the cross touch on? Trinity and Incarnation, reversed in structure: one nature three persons; one person two natures.
• Does the human soul have some operation by itself, not in the body? Aristotle: yes, understanding and willing, but not sensing and imagining.
• Why is sense knowledge “more the matter of the cause”? (student) Images are that out of which the agent intellect abstracts; the agent intellect is the chief cause.
• Does what change is change? No; the mind knows changing things changelessly, and the way we know is not the way things are.
• Is the definition of stupidity stupid, the definition of evil evil? No; to know evil is good, to love evil is evil.
• Will the beatific vision be through the senses? No.