50. Book 9 Structure: Potency and Act in Metaphysics

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Lecture Notes

Main Topics #

Structure of Book 9 #

Aristotle’s Book 9 is divided into three parts:

• First part (Readings 1-4): Potency and act primarily in relation to motion and change in material substances
• Second part (Readings 5-6): Potency and act understood universally, applicable beyond motion to form, operations (understanding, willing, sensing), and immaterial beings
• Third part: The order and priority of act over potency, establishing that act is before ability in almost every way (temporally, causally, and in excellence)

Progression from Particular to Universal #

Wisdom characteristically moves from less universal to more universal understanding. In Book 9, this progression is particularly clear:

• First part: Potency/act as found in things that move and change (most known to us, but least actual form of act)
• Second part: Potency/act in completely universal way (applicable to immaterial substances and God)
• This mirrors the natural epistemology: we cannot understand unchanging things without first understanding change, since unchanging is defined by negation of change

Why Book 9 is Central #

Berquist emphasizes that if forced to teach only one of Books 6-10 on being, he would choose Book 9 because:

• It leads directly to knowledge of the first cause, which is the ultimate goal of philosophy
• Understanding the priority of act over potency reveals that the first cause must be pure act, not matter
• It demonstrates why modern materialism errs: matter is potency, which is inferior to act, yet materialism identifies the first principle with matter

The Problem of Schizophrenia in Modern Thought #

Two seemingly contradictory conclusions about the end of all knowledge:

1. By natural reasoning: The end of all knowledge is the first cause (what explains all effects)
2. By another argument: The end of all knowledge is the best thing (since the end is always better than means)

Resolution: If the first cause is also the best thing, all harmonizes. But if not (as modern materialism claims), we have irresolvable contradiction. Modern materialists are trapped because:

• They identify the first cause with matter (potency)
• But potency is inferior to act
• Therefore their first principle is not the best thing
• This creates schizophrenia: the end of thinking is not what is best

Key Arguments #

On the Two Main Divisions of Being #

The science of being as being (metaphysics) considers being according to two main distinctions:

1. Being according to the figures of predication (Books 7-8): substance, quantity, quality, relation, etc. All other categories are referred back to substance as primary.
2. Being according to potency and act (Book 9): The fundamental division that applies to all beings and reveals the structure of causality

On Knowledge of the First Cause #

Understanding act and potency is necessary for arriving at knowledge of the first cause because:

• The third part of Book 9 demonstrates that act is before potency in almost every respect
• This leads naturally to the conclusion that the first cause must be pure act (actus purus)
• Pure act is also the best thing, harmonizing with the principle that the end of knowledge must be what is best

On the Priority of Act #

The third part will show that act is before potency:

• Temporally: In time, actually existing things precede potential things
• Causally: What actualizes potency must already be actual
• In excellence: Act is always better than potency because potency exists for the sake of act

Important Definitions #

Potency (δύναμις/potentia) #

Berquist emphasizes translating δύναμις as “ability” rather than “power” in English because the English word “power” does not naturally extend to passive senses, while “ability” does. Key senses:

• First (primary) sense: Active potency—the ability to act upon another thing
• Second sense: Passive potency—the ability to be acted upon (e.g., wood is “burnable”)
• Third sense: Resistance to change—the firm disposition not to undergo corruption
• Fourth and fifth senses: Ability to act/undergo excellently or well
• All senses refer back to the primary sense of active ability

Act (ἐνέργεια/actus) #

Initially understood narrowly as motion (what is most known to us but least actual). In the second part, understood universally:

• Form as act (not just motion)
• Operations: understanding, willing, sensing
• Pure act: Being without any potentiality (God)

Motion (κίνησις) #

“Motion” here means change generally—not just local movement but qualitative and quantitative change. It is the act which is most known to us but least actual in its actuality.

Examples & Illustrations #

The Boxer Example #

Berquist contrasts himself (a non-boxer) with Cassius Clay:

• Only Cassius Clay has the ability (active potency) to beat someone
• Berquist is “beatable” (passive potency)—able to be acted upon
• The passive ability is defined in reference back to the active ability: Berquist is beatable by someone who has the ability to beat

The Pianist and Piano #

• The pianist has the active ability to play the piano
• The piano has the passive ability to be played (is “playable”)
• If keys stick, the piano is not truly playable because it cannot be played well
• All passive abilities refer back to active abilities: the piano is playable by a pianist who has the ability to play

Spatial Imagery of Acting Upon #

Berquist notes that “acting upon” and “undergoing” are originally spatial concepts:

• To act upon something suggests being above it spatially
• “To overcome” (overcome Caesar) comes from the spatial idea of being above
• “Underdog” reflects this same spatial hierarchy
• Eventually we drop the spatial element, but it illustrates the fundamental relationship

Notable Quotes #

“The reason that knowledge talks about the accidental being hardly is, right?”

“Accidental being hardly is. So the science of being, as being, are you going to talk about that, really? No.”

“This is characteristic of wisdom to go from, to some extent, the less universal to the more universal.”

“I’d probably begin to answer that question by saying, I can’t think of anything better to think about [than God].”

“If the first cause is also the best thing there is, well then, as Aristotle says in the Nicomachean Ethics, truth, all things harmonize, everything fits together. But if the first cause is not the best thing, well then you’ve got… schizophrenia.”

“It’s the second kind of mistake outside of words. A very common kind of mistake that’s made.”

Questions Addressed #

What is the structure of Book 9? #

Book 9 has three parts: (1) potency and act in relation to motion in material things; (2) potency and act understood universally, beyond motion; (3) the order and priority of act over potency.

Why does Berquist emphasize Book 9 over other books on being? #

Because it most clearly shows how understanding being as being, specifically the distinction of potency and act, enables us to arrive at knowledge of the first cause, which is the ultimate goal of philosophy.

Why is there “schizophrenia” in modern thought? #

Modern materialism claims the first cause is matter (potency), but reason shows that (1) the first cause must explain all effects, and (2) the end of knowledge must be what is best. Since potency is inferior to act, matter cannot be both the first cause and the best thing. This creates an irresolvable contradiction.

How does the progression from particular to universal work in Book 9? #

The first part treats potency and act narrowly, in relation to motion in changing things. The second part expands to see act universally—in form, operation, and even in immaterial beings and God. This progression mirrors our natural way of knowing: we must understand change before unchanging things.

Why must we study material things before immaterial things? #

Because our minds first know through sense and imagination, which present us with material, changing things. Unchanging things are known by negation of change. We cannot grasp what is unchanging without first understanding what changes. Therefore, study of matter and form precedes study of pure form and pure act.