25. Two Potencies and Two Acts in Sensation and Understanding

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Lecture Notes

Main Topics #

The Two Senses of Potency and Act #

Aristotle distinguishes between two fundamentally different senses of potency (δύναμις/potentia) and act (ἐνέργεια/actus):

• First potency: The capacity to acquire a power (e.g., a child’s native ability to learn geometry)
• Second potency: Possessing a power habitually (e.g., having learned geometry but not currently thinking about it)
• First act: The acquisition of knowledge or skill (learning)
• Second act: The actual exercise of that knowledge (actively thinking about a geometric theorem)

Berquist uses the example of a geometry student: before learning, the child has the first potency (ability to learn); after instruction, the child has acquired the science (first act); the child now possesses geometry habitually (second potency); when actively thinking about a theorem, the child is in second act.

Why Understanding Is Treated First #

Aristotle reverses the normal pedagogical order by discussing reason first, then applying the distinction to sensation. This is unusual because sensibles are generally more known to us than intelligibles. However, the double structure of potency and act is more evident in reason than sensation, making it a clearer starting point for analysis.

The Distinction Applied to Sensation #

Sensation mirrors the structure found in understanding:

• We acquire senses by generation (in the womb), not by learning
• Once we have a sense (e.g., sight), we still need the external sensible object present to actually sense
• The sense in potency is actualized by the sensible object acting upon it
• Unlike the mind (which can think about universals at will), sensation requires the present object

Alteration vs. Perfection #

Learning appears to be alteration but is more properly characterized as perfection:

• True alteration involves loss of one form and gain of a contrary form (hard becoming soft)
• Learning involves a movement toward fulfillment of nature, not a loss
• When the slave boy goes from false opinion to true knowledge, this resembles alteration but is really a perfection
• Once knowledge is acquired, exercising it is not alteration at all—it is a kind of flowering or increase of what one already possesses

Berquist notes that we properly use the word “change” when going from contrary states (thinking one thing, then its opposite). But acquiring entirely new knowledge that one had no prior opinion about is better described as perfection than change.

Two Modes of Undergoing (πάσχειν/pati) #

Berquist distinguishes between two senses of undergoing:

1. Undergoing as destruction: Change to a privative disposition (contrary state)—genuine loss of form
2. Undergoing as perfection: Receiving form from what is actual; fulfillment of nature (ἕξις/hexis, state; φύσις/physis, nature)

Sensation exemplifies the second mode: the sense receives the form of the sensible object without losing its own form or suffering privation.

The Problem of Matter vs. Mind in Reception of Form #

Berquist illustrates a crucial distinction using the example of Michelangelo carving a statue:

• Material reception: A block of marble loses its irregular shape and takes on the artist’s shape; the marble is deprived of one form and receives another
• Mental/Sensory reception: When I see a person, the shape enters my eye and memory without my eye losing its shape or becoming carved; I am perfected by having new forms, not deprived

This shows why the knower is not altered in the strict sense when receiving knowledge.

Key Arguments #

The Argument from Habituation #

• The slave boy in Plato’s Meno is first mistaken about doubling a square (he thinks doubling the side works)
• Socrates shows him he is wrong, and then teaches him the correct method using the diagonal
• This progression from ignorance/error to knowledge appears to be alteration (like something becoming hard from soft)
• However, it is more properly a perfection because one moves into actuality from potency, not from a contrary state
• Conclusion: Learning is not simple alteration but a type of change toward fulfillment

The Argument from the Exercise of Knowledge #

• Once a teacher has learned a subject thoroughly, when teaching it, does he undergo alteration?
• No. A cook does not become “altered” when cooking; a house builder does not become “altered” when building
• When an educated person exercises knowledge they already possess, they are becoming actual in what they already have habitually
• This is merely an increase or flowering of an existing possession, not a change in nature
• Conclusion: Exercising knowledge is not alteration; it is a perfection of existing knowledge into actuality

The Argument from the Presence of Objects #

• If the senses already possessed their objects (as Empedocles suggested), they would always be sensing
• But we do not always sense; we sense only when the object is present and we attend to it
• Therefore, the senses are in potency to their objects and must be actualized by external things
• Conclusion: Sensation is fundamentally a being acted upon (undergoing) by the sensible object

The Argument from Will in Understanding vs. Sensation #

• After acquiring a science (e.g., geometry), I can think about it whenever I wish, provided nothing external prevents me
• I cannot see a particular friend whenever I wish; he must be present
• Reason: Universals exist in the soul; particulars exist outside the soul
• Therefore, understanding operates independently of external objects once acquired, but sensation necessarily depends on the present object

Important Definitions #

Potency (δύναμις/potentia) #

The capacity or ability. The word in English can misleadingly suggest active power (as in “potent” or “omnipotent”). Berquist prefers “ability” as a more neutral translation. Two senses:

1. Capacity to acquire a power
2. Habitual possession of a power

Act (ἐνέργεια/actus) #

Actualization or exercise. Two senses:

1. The acquisition of a power
2. The active exercise of that power once acquired

Undergoing (πάσχειν/pati) #

Being acted upon. Originally meant suffering in the sense of being harmed; extended to mean reception of form from an external agent. Two modes:

1. As destruction (loss of form)
2. As perfection (fulfillment of nature)

Alteration (ἀλλοίωσις/alteratio) #

Change from one contrary state to another. The strict sense involves loss of one form and acquisition of a contrary form. Learning is not simple alteration in this sense.

State/Having (ἕξις/hexis) #

A dispositional quality or habit. The intermediate condition between potency and act, where a power is possessed but not being exercised.

Nature (φύσις/physis) #

The fulfillment or natural operation of a thing. Used to distinguish perfection (a fulfillment of nature) from alteration (a change away from nature).

Examples & Illustrations #

The Geometry Student #

A child begins with the first potency (ability to learn geometry); through instruction, acquires geometry (first act/habitual possession); possesses it in a latent state (second potency); when actively thinking about a theorem, exercises second act. The acquisition involves struggle; the exercise is easy and pleasant, with no struggle once the science is possessed.

The Slave Boy (Plato’s Meno) #

Initially mistaken about doubling a square (thinks doubling the side works). Socrates corrects him and then teaches him using the diagonal method. This progression from false opinion to true knowledge resembles alteration (like something becoming soft from hard) but is more properly a perfection of the intellect.

Teaching Geometry #

A teacher who has mastered a theorem, when explaining it to students for the tenth time, is not being “altered” or “learning” in the strict sense. He is becoming actual in his habitual knowledge in a new instance. This is a flowering of what he already possesses, not a change in nature. A teacher does not learn when teaching what he already knows; he merely becomes active in exercising existing knowledge.

Carving a Statue vs. Seeing a Person #

Michelangelo carving marble: The marble loses its irregular shape and receives a new shape as its own (genuine alteration, with privation). When I see you: Your shape enters my eye and memory without my eye losing its shape or being deprived. I am perfected by having your form, not harmed or altered. This illustrates why receiving knowledge/sensation is not alteration in the strict sense.

The Pope Speaking #

When a pope speaks in Spanish or Polish to people who don’t know those languages, listeners hear the sounds (sensation via ears) but don’t understand (they don’t know what stands under those sounds). Understanding requires knowing what the word stands under—its meaning or referent.

Questions Addressed #

Why does learning appear to be alteration? #

Learning resembles alteration especially when one moves from false opinion to true knowledge (the slave boy goes from thinking you double the side to understanding the diagonal method). This involves change from a contrary state, which resembles genuine alteration. However, it is more properly a perfection because learning is a movement into actuality from potency, fulfilling one’s nature, not corrupting it.

Is teaching a form of learning for the teacher? #

No. A teacher properly speaking is one who knows and teaches what he knows. If a professor learns something while teaching it, he is not yet fully a teacher with respect to that material. Exercising knowledge one already possesses is not learning but becoming active in what one habitually has.

Why can we think about geometry at will but not see a friend at will? #

Universals (like the concept of a triangle) exist in the soul and are independent of external objects. Once we possess the science of geometry, we can activate this knowledge whenever we wish. Particulars (like this friend) exist outside the soul and require their presence to be sensed. Sensation necessarily depends on the present object; understanding does not.

How does sensation differ from matter receiving form? #

When matter receives form (as marble receives the shape of a statue), the matter loses its previous form and takes on a new one. When a sense receives the form of a sensible object, the sense organ does not lose its own shape or substance; it is perfected by having the form of the sensible thing. The sense receives without privation of its own form.

Notable Quotes #

“The soul is in some way all things because by sensing it’s things sensed and by understanding it’s things understood.”

“Once I’ve acquired some geometry, whenever I want to, I can think about that, right? See? So I can go right now to the board and say, you know, in a triangle, right?”

“It’s a little hard to understand the Pope now sometimes, and he speaks, right? He’s hearing his words a bit, right?… But you don’t understand what he’s saying because you don’t know what stands under those sounds.”

“Would you say that the cook, when he starts to cook dinner, he’s altered, changed? See? No, it seemed kind of strange to speak that way, wouldn’t it?”

“Neither is suffering simple… one sort is a certain destruction due to the contrary… another rather is rather the saving of a being in potency by a being in act.”

“It is not proper to say that the one judging when he judges is altered, as neither is a house builder when he builds.”

“When I go from being mistaken or being ignorant… that’s called teaching… But when I possess this in an habitual way, and I actually think about it… Am I being taught? Am I learning? No.”