Summa I q.84 a.7: Why We Think Through Images, and Why the Brain Isn't the Organ of Thought

Orientation #

He begins directly on “the seventh” article and closes: “Next time we do Article Eight, and then we’ll start on the next one here … modus ordinarii intelligendi” [ed.: garbled; likely the next question on the mode and order of understanding]. The previous class worked through the earlier articles of q. 84 on whether intellectual knowledge is derived from sensible things. (The verified-sources list says a. 8 is matched for 5 minutes, but the transcript itself ends before a. 8 is read; the transcript is followed here.)

The class, in order #

1. The objection, and the brain-as-organ argument (“blow on the eye interferes with seeing”) #

Point: a. 7 asks whether the understanding can understand in act through the forms it already has, without turning to the phantasms; he frames it with Aristotle, De Anima III: even with the understandable in act in your mind, to think what a triangle is you must form an image of a triangle and consider the what-it-is of what you imagine — universal in itself, but the what-it-is of something imagined. Hence an injured imagination interferes with thinking.

• A “tough-minded modern” student’s argument (told as an anecdote): a blow on the eye interferes with seeing, so the eye is the organ of sight; a blow on the brain (or alcohol, or lesions) interferes with thinking; therefore the brain is the organ of thought.
• His reply, the light-bulb example: in a windowless room lit by one bulb, he smashes the bulb with a book and you can no longer see him — so “the light bulb is the organ of sight”? No: a blow on the eye interferes on the side of the organ; smashing the bulb, or your leaving the room, interferes on the side of the object. So the brain’s connection with thinking is real, but the fact of interference does not tell you whether the connection is one of organ or one of object.
• Since Aristotle’s other arguments show reason is not a body, the brain cannot be its organ; it must be related to thought as object. Aristotle’s proportion: images are to thinking as exterior things (colour, sound, odour) are to seeing, hearing, smelling. You cannot see the colour of something without the thing being there; you cannot think the what-it-is of something imagined without imagining it — yet that puts the image on the side of the object.
• Contrary to experience anyway: when the images are not there, we cannot think.

2. The three objections and the sed contra (“imagination does not transcend time”) #

He reads them, mostly without comment.

1. The understanding comes to be in act through the understandable form informing it; to be in act is to understand; so the forms suffice without turning to phantasms.
2. Imagination depends more on the senses than understanding on imagination; yet imagination can imagine in act with sensible things absent; a fortiori the understanding.
3. Of bodiless things there are no images, since imagination does not transcend time and the continuous; so if understanding needed phantasms it could not understand anything bodiless — clearly false, for we understand truth itself, God and the angels to some extent.

• Sed contra: the Philosopher, De Anima III: the soul understands nothing without an image.

3. The answer: two signs from experience (“as in those who are beside themselves”) #

Point: in this present life, joined to a body that undergoes, our understanding cannot understand in act except by turning to images — shown first by two signs (indications), then by a reason.

1. First sign: the understanding is a power using no bodily organ, so it could not be impeded by injury to a bodily organ unless its act required the act of a power that does use one (sense, imagination, memory, the other sense powers). Experience shows it is so impeded — the imagination is tired, or one is asleep and not in control of one’s images, or “phrenetic” (beside oneself), or the memory power is injured — and a man is then impeded from understanding even what he already knew. So turning to images is needed not only in first acquiring knowledge but in using knowledge already acquired: “I’ve acquired some geometry, but if I want to think about what a triangle is, I imagine a triangle.”
2. Second sign: everyone can experience in himself that when he tries to understand something he forms images for himself, as examples in which he inspects what he wants to understand; and when we want to make another understand, we propose examples to him from which he can form suitable images.

• Aside: doing Euclid’s solid geometry, his imagination was not good enough, so he built cardboard figures and hung one from the kitchen light “to pursue my higher studies” (student: “That drove your wife crazy”).

4. The reason: the knowing power is proportioned to the knowable (“of the nature of the stone that it be in this stone”) #

1. The knowing power is proportional to the knowable.
2. The angel’s understanding, wholly separated from body, has as its own object an understandable substance separated from body, and through such understandables knows material things.
3. Man’s understanding, joined to a body, has as its own object the quidditas — the what-it-is, or nature — existing in bodily matter; through these natures of visible things it ascends to some knowledge of invisible, immaterial things.
4. It belongs to such a nature to exist in some individual (unlike Plato’s world of forms): it is of the nature of stone to be in this stone, of horse to be in this horse. So the nature of stone cannot be known completely and truly except as existing in this particular.
5. The particular is apprehended by sense and imagination; therefore, to understand its own object in act, the understanding must turn to the images so as to look upon the universal nature existing in the particular (“when I think about what a cat is, I imagine a cat”).
6. Had the proper object been a separated form, or had natures of sensible things not subsisted in particulars, as the Platonists thought, this turning would not be necessary.

• The bookmark example (Aristotle’s proportion again): the colour of this bookmark is in no way the organ of his sight, and the seeing takes place “up here”, not in the bookmark; yet take the bookmark out of the room and he cannot see its colour. Likewise the proper object of understanding is the what-it-is not of an immaterial thing but of something sensible (man, dog, tree) or imaginable (square, circle); it cannot understand what a triangle is without at least an image of one, “because this is the what it is of what he’s imagining … not an object existing by itself.”
• This is what misleads people into calling the brain the organ of thought: injury interferes with thinking, but on the side of the object, because it impedes the production of the phantasms. (Student aside: that is why we imagine someone we have not met differently from how they are.)

5. Reply to the first objection (“exist in it habitually”) #

Point: the species conserved in the possible understanding exist in it habitually, which is not yet understanding in act; to understand in act it is not enough to conserve the species — we must use them according as they belong to the things of which they are the species, i.e. natures existing in particulars. So without the singular represented in the imagination, one cannot think its what-it-is. (He reads only this reply; replies to objections 2 and 3 are not taken up in the recording.)

• He goes back to the light-bulb and leaving-the-room examples to fix the organ/object distinction.
• Student’s example: smash the piano and there is no more piano music, but that does not prove there was no piano player. His verdict: “not exactly the same comparison.” His own: “if we blow you up, that interferes with my seeing you” — not because you are the organ of my sight but because the colour of your garment, the red machine, the bricks, the fire extinguisher, is its object.

6. Two bad arguments, two kinds of defect (“wishful thinking … not logical thinking”) #

Point: put the brain argument in logical form and it fails one way or the other.

• Argument 1: If the brain is the organ of thought, a blow on the brain interferes with thinking; a blow does interfere; therefore the brain is the organ of thought. Class: not good. Both premises are true, but the conclusion does not follow — “the matter is good, but the form is bad” (reasoning from affirmation of the consequent to affirmation of the antecedent).
• Argument 2: If a blow on the brain interferes with thinking, the brain is the organ of thought; a blow does interfere; therefore the brain is the organ. Here the conclusion follows, but the first premise is not necessarily true — “the form is good, but the matter is bad” — since the only connection need not be that of organ (the light bulb again).
• Two defects an argument can have: false premise(s), or conclusion not following. Either one makes the argument bad; a good argument needs both true premises and necessary consequence.
• Examples for affirming the consequent: “If Berquist dropped dead last night, he will be absent; he is absent; therefore he dropped dead” — wishful thinking. “If I’m a dog, I’m an animal; I’m an animal; therefore I’m a dog.” “If I’m the man who murdered his wife, I’m a man …”; “if you’re the man who robbed the bank today, you are a man; you are a man; therefore …” — “I put you all in jail today.”
• Note on if-then statements: they can be true though the simple statements are false — “if Socrates is a mother, Socrates is a woman”; “if I am the number two, I am half of four.” The conditional says only that if this is so, that will be so; it does not assert that in fact the brain is the organ of thought.
• Checkbook comparison: four people at $20 each is $100 — right numbers, multiplied correctly. “Three students at $20 is $60” — multiplied correctly but with a wrong number. Your checkbook goes off either because you added or subtracted wrongly or because you had the wrong number (illegible entry, misplaced decimal) — or both. Aristotle’s refutation of Melissus in Physics I: false premises and a conclusion that does not follow, both defects.
• Aside on Aristotle: the Prior Analytics looks at whether something follows necessarily, the Posterior Analytics at whether the premises are necessarily true; both are required for certainty. Demonstration: a syllogism whose premises are necessarily true, hence whose conclusion is necessarily true. Dialectical syllogism: premises only probable opinions, conclusion only probable. Induction, enthymeme, example: conclusion does not follow necessarily — “the last Honda I bought lasted ten years, so the next will” — yet we use such arguments all the time.

7. Extracting the form: when B can come from many things (“If Rosie is a horse, then Rosie is an animal”) #

Point (answering a student who asked for the shorthand): logicians extract the form — if A then B; B; therefore A — and it fails because B may result from many things.

• Case 1: A is less universal than B. If Rosie (the dog in the room) is a cat, Rosie is an animal; if Rosie is a horse, Rosie is an animal — all true; Rosie is an animal (“She’s a beast, actually”); nothing follows.
• Case 2: A is one of many possible causes of B. If Berquist is visiting his grandchildren, or sick, or his car broke down, or there is a snowstorm, he will be absent; his absence tells you none of these in particular — “you might have forgot.”
• Astronomical example: if the sun goes around the earth, there is day and night; there is day and night; therefore the sun goes around the earth — does not follow, since the earth’s turning on its axis would also yield day and night; the fact of day and night does not tell you which.
• Political example: if I am opposed to Wesley Clark on abortion I will vote against him — but someone else may vote against him for some other reason (“I’m not serious”).
• Conclusion: neither version shows that the brain is in fact the organ of thought. Student: “I couldn’t see it until you did the A and B.”

8. The four forms of the if-then argument (“if A is so, then B is so”) #

Point: a student asks how many forms have a necessary conclusion; he gives two valid and two invalid.

1. Valid, obvious: if A then B; A; therefore B. Admitting the conditional is admitting B follows necessarily from A, without yet saying either is in fact so.
2. Valid, less obvious: if A then B; not B; therefore not A. Shown through the first, since we show what is not obvious through what is obvious: the three statements “if A then B”, “A”, “not B” are incompatible (the first two, by form 1, contradict the third); so given the first and third as true, “A” must be false.

• So to show a statement by the if-then argument you look before it; to overthrow it you look after it. Socrates in the Meno uses both (arguing with probability): if virtue is knowledge it can be taught, virtue is knowledge, so it can be taught; and if it can be taught there will be teachers of it, there are none, so it cannot be taught.

3. Invalid: if A then B; not A; therefore not B — “if I am a dog I am an animal; I’m not a dog; therefore I’m not an animal — I’m a cat.”
4. Invalid: if A then B; B; therefore A (the dog/animal example again).

• You can disprove a form by examples but cannot prove one by examples: if it were necessary it would always hold when the premises hold; one example shows it is not always so, hence not necessary (using form 2: if necessarily so, then always so; not always so; therefore not necessarily so). One black man disproves “man is always white”; no number of white men proves it, even if the world went on forever; 3, 5, 7, 9 … never prove every number is odd.
• Applied: “if the brain is the organ of thought, a blow interferes; a blow does interfere; therefore…” — not a syllogism. The reverse conditional is false because there is another possibility: interference on the side of the object.

9. Back to the brain: organ of images, not of thought (“use your brain when you have one”) #

Point: the parallel of love shows the same ambiguity — if I don’t love something, the defect may be in my heart or in the object: not loving cancer, the defect is in the object; not loving God, in my heart.

• Most of the academic world speaks of the brain as the organ of thought because of the evident connection and because “we use our brain when we think” (his wife works for the Mass. Brain Injury Foundation, whose slogan is roughly “use your brain when you have one”). But the brain is on the side of the object: “it’s the organ of phantasms or the organ of images.”
• Restated with Aristotle’s proportion: he does not see colour in the abstract but the colour of that robe in front of him; we understand what a triangle is, but a triangle does not exist by itself (the Platonic mistake, the world of forms) — it is the what-it-is of this individual triangle, as “what a dog is” is the what-it-is of Rosie. What we understand directly is the universal, the what-it-is; but never without in some way imagining an individual.

His words #

• “the third book about the soul”: his name for De Anima III.
• “understandable forms/species”: species intelligibiles [ed.: intelligible species].
• “the what it is”: quidditas; also “the nature” existing in bodily matter.
• “phantasms” / “images”: used interchangeably for the imagination’s content.
• “a undergoing body”: his rendering of corpus passibile [ed.: passible body].
• “beside themselves”, “the phrenetic”: those whose imagination is injured.
• “organ” vs “object”: the two possible connections of the brain with thinking.
• “matter” vs “form” of an argument: truth of premises vs. whether the conclusion follows.
• “affirmation of the consequent / of the antecedent”: his names for the invalid and valid conditional inferences.
• “Natural Philosophy, first book”: Physics I (refutation of Melissus).
• “Prior and Posterior Analytics, we call them in English.”
• “demonstration”, “dialectical syllogism”, “induction, enthymeme, example”: the kinds of argument as he distinguishes them.

Texts #

Read in class

• Thomas Aquinas, Summa Theologiae I, q. 84, a. 7: objections 1–3, sed contra, body, reply to obj. 1 (verified source; replies 2–3 not read).

Mentioned

• Aristotle, De Anima III: soul understands nothing without an image; the proportion images : understanding :: exterior things : senses.
• Aristotle, Physics I: refutation of Melissus (verified-source handout “Note for Book One of Natural Hearing, Reading I” may be in use here; the transcript only names the refutation).
• Aristotle, Prior Analytics and Posterior Analytics.
• Plato, Meno: Socrates’s two if-then arguments on virtue (verified-source handout on the Meno may be in use; the transcript only names the argument).
• Plato / the Platonists: separated forms, “world of forms”.
• Euclid, solid geometry (his cardboard figures).
• Verified-source handout “The First Definition of Reason”, p. 103: not named in the transcript.
• Summa Theologiae I, q. 84, a. 8: announced for next time, not read.

His questions #

• If a blow on the light bulb interferes with your seeing, is the light bulb the organ of sight? No — it interferes on the side of the object, not the organ.
• Can I see the colour of this bookmark if you take it out of the room? No; yet the bookmark is in no way the organ of my sight.
• “If the brain is the organ of thought, then a blow on the brain interferes with thinking; a blow does interfere; therefore the brain is the organ of thought” — is that argument good? No: premises true, conclusion does not follow (bad form).
• In the second version (if a blow interferes, then the brain is the organ), does the conclusion follow? Yes, but the if-then premise is not necessarily true (bad matter).
• If Socrates is a mother, then Socrates is a woman — true or false? True, though Socrates is not a mother; conditionals do not assert their parts.
• If I’m the man who robbed the bank today, then I’m a man; I’m a man; therefore …? Does not follow — “I put you all in jail today.”
• If the sun goes around the earth there is day and night; there is day and night; therefore the sun goes around the earth — does that follow? No; the earth turning on its axis is another possible cause.
• How many forms are there where the conclusion necessarily follows? Two: affirm the antecedent, or deny the consequent.
• How many black men do you need to disprove “man is always white”? How many white men to prove it? One; no number would prove it.
• Can you say “if I don’t love something, the defect is in my heart”? No — it may be in the heart or in the object.