54. Act and Ability: From Motion to Universal Understanding

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Lecture Notes

Main Topics #

The Ascent to Universal Understanding of Act #

• Aristotle moves from examining act specifically as motion (Readings 1-4) to examining act universally (Readings 5-6)
• This methodological approach mirrors Aristotle’s treatment of substance and the one (ἕν/hen): ascending from less universal to more universal considerations
• The goal is to show that act applies even to immaterial things not subject to motion in the strict sense
• With the universal treatment of act comes a new, broader understanding of ability (δύναμις/dynamis)

Why Act Cannot Be Defined #

• Fundamental Principle: Not everything can be defined; some things must be known without definition
• Logical Parallel: Just as not every statement can be proven (this would require infinite regress and make knowledge impossible), not every term can be defined
• If every definition required a prior definition, infinite regress would prevent any knowledge of essences
• Therefore, some things must be known without definition—these are foundational to all other knowledge
• Act is one of these fundamental, indefinable realities
• Ability (δύναμις/dynamis), by contrast, can be defined—it is defined through act: “the beginning or source of motion in another or in the same thing as other”

Act Known Through Induction and Proportion #

• Since act cannot be defined, Aristotle employs two methods to make it known:
  1. Induction (ἐπαγωγή/epagoge): Examining particulars to grasp the universal
  2. Proportion (ἀναλογία/analogia): Seeing likeness of ratios (not merely mathematical ratio, but analogy)
• Proportion Examples from Aristotle:
  • The one actually building is to the house builder as the one awake is to the one asleep
  • The one seeing is to one with eyes closed (but not blind) as formed matter is to matter
  • That which is worked up is to the unworked
• These examples show act can be understood by grasping how it relates to ability in different domains
• Form is proportional to matter as seeing is to the eye closed but capable of sight

Equivocation by Reason (Λόγος/Logos) #

• Act is said equivocally in multiple senses, but not equivocally by chance
• It is equivocal by reason of proportion: the word “act” is applied to different realities because they share a proportional relationship
• The primary sense is act as motion or doing (τὸ κινεῖσθαι/to kinesthai)
• The secondary sense extends to form, understood as proportional to matter just as motion is proportional to ability
• Form is also both:
  • The end of motion (what motion tends toward)
  • The beginning of further motion (things act through their form)
• This shows act is not merely an accident of language but rooted in the intelligible structure of reality

Two Fundamental Kinds of Act #

Imperfect Acts (Motion/Doing) #

• Characteristic: Essentially incomplete while occurring; cannot coexist with their completion
• Examples: Walking, building a house, learning, making dinner, becoming healthy
• Grammatical test: “I am walking” and “I have walked” are mutually exclusive
  • While walking, you have not yet walked (incomplete)
  • When you have walked, you are no longer walking (complete, activity ceases)
• Nature: These acts have a limit or end toward which they tend, but no part of the act is fully realized until completion
• Transitive character: Often involve external matter (building acts upon a house; teaching acts upon students)

Perfect Acts (Operations/Ἐνέργεια/Energeia) #

• Characteristic: Complete while occurring; the completion does not terminate the act
• Examples: Seeing, understanding (νοεῖν/noein), loving (ἀγαπᾶν/agapan), sensing
• Grammatical test: “I am seeing” and “I have seen” can be simultaneous
  • While seeing, you have already seen (complete at every moment)
  • When you have seen, you remain in the state of seeing
• Nature: The act remains whole within the agent at every moment; it does not tend toward an external completion
• Intrinsic character: These acts remain within the agent; they do not require external matter for their completion
• Philosophical importance: These constitute human happiness and flourishing (εὐδαιμονία/eudaimonia), not the imperfect acts

The Problem of Naming #

• Latin uses motio for imperfect acts and operatio for perfect acts, but these terms are imperfect
• Aristotle’s Greek text uses different terminology that does not translate perfectly into English or Latin
• The distinction itself is more important than the naming conventions

The Infinite and Unsatisfied Ability #

• Some abilities can never be fully actualized
• Example: The Continuous Line
  • A straight line can be bisected infinitely
  • Each bisection produces two shorter lines (never points or nothingness)
  • The ability to divide is never fully satisfied
  • One cannot create points from a line through division; points are actualized only through the cut, but the result is always lines
• Other examples: The ability of numbers to increase indefinitely; the ability to reflect upon oneself infinitely (“I know that I know that I know…”)
• This represents a third category of ability: one that remains open infinitely, distinct from both fully actualizable abilities and form

Key Arguments #

Against Descartes and Locke on the Indefinability of Motion #

• The Error: Both philosophers denied that motion could be defined, claiming it is a “simple idea” that cannot be decomposed
• Descartes’ Dismissal: He quoted Aristotle’s definition garbled and said “Who understands that by just playing with words?”
• Locke’s Position: Motion is simple and simple ideas cannot be defined
• Aristotle’s Response: Motion can be defined through act and ability: “the act of what is able to be, insofar as it is able to be”
• The Consequence of Denying Motion’s Definability:
  • If motion is undefined, then natural philosophy (which depends on understanding motion) is compromised
  • The entire argument for the unmoved mover (the first and most manifest argument for God’s existence) collapses
  • The consequences are grave for metaphysics and natural theology

The First Argument for God’s Existence #

• Motion is the most known act to us (things in motion catch the eye immediately)
• Yet motion is the least actual of acts (no part of motion is ever fully actual; it is essentially incomplete)
• This exemplifies Aristotle’s principle: what is most known to us is least noble in being; what is least known is most noble
• The argument proceeds: from things in motion → to the necessity of an unmoved mover → to the existence of God
• Without a clear definition and understanding of motion, this foundational argument cannot be made

Important Definitions #

• Act (ἐνέργεια/energeia): The existence of a thing, not in the way of ability; the actualization of potential. Act can be understood through induction and proportion rather than definition.
• Ability (δύναμις/dynamis): The beginning or source of motion in another or in the same thing as other. Can be partially defined through the act to which it tends.
• Form (εἶδος/eidos): The actualization of matter; a perfect act. Form is simultaneously the end of motion and the beginning of further motion.
• Perfect Act (ἐνέργεια τέλεια/energeia teleia): An act that is complete while occurring; examples include seeing, understanding, loving. The act remains within the agent.
• Imperfect Act / Motion (κίνησις/kinesis): An act that is incomplete while occurring; essentially incomplete. Examples include walking, building, learning. The act tends toward an external completion.
• Proportion (ἀναλογία/analogia): A likeness of ratios (not a mathematical ratio per se, but an analogical relationship). The means by which equivocal terms like “act” are related by reason rather than by chance.
• Equivocal by Reason (κατὰ λόγον/kata logon): A term applied to multiple realities not by chance, but in virtue of their proportional relationship to a primary sense.

Examples & Illustrations #

The Hermes Statue #

• Wood before being shaped has the ability (δύναμις/dynamis) to be a statue of Hermes
• When the wood is shaped, it becomes actually a statue (form is actualized as a perfect act)
• This illustrates: matter in ability → form as act
• Michelangelo saw a slab of marble and saw in it the potential Pietà waiting to be actualized

Geometric Division #

• A parallelogram contains two triangles in ability (δυνάμει/dynamei) before a diagonal is drawn
• Drawing the diagonal actualizes the two triangles
• This demonstrates act and ability in mathematical objects not subject to physical motion
• The two triangles are present in the parallelogram potentially, then actually

Seeing and Geometry Proof #

• A student studies geometry: while studying, the student is learning (imperfect act, ability being actualized)
• When the student goes to the board and diagrams the Pythagorean theorem, the student is going from ability to act
• This is an example of an imperfect act (motion from potential knowledge to actual knowledge)
• The student moves from ability to understand → to actually understanding

Perfect vs. Imperfect Acts Compared #

• Walking home (imperfect act): While walking, I have not yet walked home. When I have walked home, I am no longer walking.
• Seeing you (perfect act): While seeing you, I have already seen you. The act of seeing is complete at each moment.
• Building a house (imperfect act): While building, the house is not built. When it is built, building ceases.
• Loving (perfect act): While loving you, I have already loved you. The act of love is complete in the present moment.
• Understanding a triangle (perfect act): While understanding what a triangle is, I have understood it. The understanding remains complete throughout.

Reading and Cognition #

• Reading a page: an imperfect act (while reading, you have not yet read it)
• Thinking about what you have read: a perfect act (you are simultaneously thinking and have thought)
• This shows the difference in structure between activities that are ordered to a completion and those that contain their completion

Notable Quotes #

“Act, then, is the existence of a thing, not in the way in which we say an ability.” — Aristotle, Physics IX, as read by Berquist

“One should not seek a definition of everything.” — Aristotle, Physics IX, cited approvingly by Berquist

“If every statement was in need of being proven, you couldn’t even begin to prove anything.” — Berquist, explaining Aristotle’s principle that not all statements require proof

“Not everything had to be defined… Something had to be known without definition.” — Berquist, on the necessity of foundational indefinables

“At the same time, we are living well, and have lived well, right? And are happy, and have been happy.” — Aristotle, Physics IX, illustrating the perfect act of happiness

“For every movement is incomplete.” — Aristotle, Physics IX, defining the essential incompleteness of imperfect acts

“The one who is actually building a house, is to the house builder, as the one who is awake, is to the one who is asleep.” — Aristotle, Physics IX, providing proportional examples for understanding act

Questions Addressed #

Why can’t act be defined? #

• Act is a fundamental, irreducible reality
• If everything had to be defined through prior definitions, infinite regress would make knowledge impossible
• Just as not every statement can be proven, not every term can be defined
• Some things must be known through induction (examining particulars) and proportion (seeing analogical relationships)
• This does not make act unintelligible; it makes it known in a primary way, rather than through definition

How do perfect and imperfect acts differ in their essential structure? #

• Imperfect acts are incomplete while occurring; they have a temporal structure directed toward a completion that terminates the act
• Perfect acts are complete while occurring; they remain whole within the agent at every moment
• Grammatically: imperfect acts make “I am X-ing” and “I have X-ed” mutually exclusive; perfect acts make them simultaneous
• This structural difference determines their suitability for happiness: happiness consists in perfect acts, not imperfect ones

How do we know act if it cannot be defined? #

• Through induction: examining particular instances to grasp the universal
• Through proportion: seeing how act relates to ability in different domains through analogical relationships
• Example: as the one awake is to the one asleep, so the one actually seeing is to the one with eyes closed (but not blind)
• This method of knowing is more primary than definition; it grasps the thing itself rather than its logical structure

Why is the distinction between imperfect and perfect acts philosophically important? #

• It determines what constitutes human happiness and flourishing
• It clarifies the nature of divine operations (God’s understanding and love are perfect acts, eternal and complete)
• It shows why the goal of human life cannot be transitive actions (making, building) but must be intrinsic activities (knowing, loving)
• It explains why happiness is an activity (ἐνέργεια/energeia), not a state or possession

Can all abilities be fully actualized? #

• No. Some abilities are never fully satisfied
• The continuous (what is divisible forever) represents an ability that remains open infinitely
• A line can be bisected infinitely, always producing shorter lines, never arriving at points or nothingness
• Numbers can increase infinitely; the ability to reflect upon oneself (“I know that I know that I know…”) is sterile infinity
• These represent a third category distinct from both fully actualizable abilities and form

Connections to Key Themes #

Methodological Ascent in Aristotle #

• This lecture exemplifies Aristotle’s method: begin with particular, less universal cases; ascend to the universal
• Readings 1-4: Act examined only as motion
• Readings 5-6: Act examined universally, applicable even to immaterial things
• This same method appears in Aristotle’s treatment of substance (material → universal) and the one (numerical → convertible with being)

The Problem of Knowing Immaterial Being #

• We know immaterial being through concepts derived from material being
• We use both concrete words (like “act”) and abstract words (like “actuality”) to speak of God
• In material things, there is a real distinction between what something is and that by which it is
• In God, this distinction does not exist (God’s essence is his existence)
• Yet we cannot simply discard one set of concepts; we must understand how they relate analogically

The Consequences of Denying Motion’s Definability #

• Descartes and Locke’s denial that motion can be defined has grave consequences:
  • Natural philosophy loses its foundation
  • The argument for the unmoved mover (the first argument for God) becomes impossible
  • The entire metaphysical edifice that depends on understanding motion collapses
• This shows why precision in metaphysical understanding is not merely academic but foundational to theology and natural philosophy