35. God's Immutability and the Nature of Motion

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Lecture Notes

Main Topics #

The Immutability of God #

• Whether God is altogether unchangeable (Question 9, Article 1)
• Whether immutability is proper to God alone
• God’s immutability as the fourth divine attribute, following from His infinity
• The relationship between immutability and eternity: just as time follows upon motion, eternity follows upon immutability

Motion vs. Operation: A Critical Distinction #

• Motion (motus): An imperfect act; defined as “the act of what is able to be insofar as it is able to be”
  • Essentially incomplete; the activity ceases when complete
  • Examples: walking home, building a house
  • When I have walked home, I am no longer walking home
  • When I have built the house, I am no longer building the house
• Operation (operatio): A perfect act; complete in itself
  • Examples: seeing, understanding, loving, sensing
  • When I am understanding what a triangle is, I have already understood it
  • When I am seeing something, I have already seen it
  • When I am loving someone, I have already loved them
  • The act is complete while occurring

Platonic vs. Aristotelian Usage #

• Plato uses “motion” (κίνησις/motus) broadly to encompass all operations and doings
• Aristotle is more precise, distinguishing motion (imperfect act) from operation (perfect act)
• Augustine speaks in the Platonic manner when referring to God “moving himself”
• Thomas notes this represents a difference in terminology rather than substantive disagreement between the philosophers

Key Arguments #

For God’s Immutability #

First Argument: From Pure Actuality

• Above it was shown that there is a first being (God) who is pure act (actus purus) without any admixture of potency
• Pure act means actuality without passive potency—the ability to be actualized
• Aristotle shows in Metaphysics IX that actuality is simply prior to potentiality
• Everything that changes in any way is in some way in potency (able to be something other than it is)
• Since God has no passive potency, God cannot change
• Conclusion: It is impossible for God to change in any way

Second Argument: From Composition and Change

• Everything that moves or changes has something that remains and something that passes away
• Example: When something changes from whiteness to blackness, the substance remains while the accident changes
• In every changing thing, there must be composition (of subject and accident, substance and form)
• It has been shown above that God is altogether simple—without composition
• Since change requires composition and God has no composition, God cannot be moved
• The definition of motion presupposes composition, which God lacks

Third Argument: From Infinity

• Everything that is moved acquires something by its motion and arrives at what it had not attained before
• God, being infinite, comprehends in himself all the fullness and perfection of being
• God cannot acquire something new or extend himself toward something previously unattained
• Therefore, motion does not belong to God in any way
• Illustration: “What do you give to someone who has everything?” If God truly has everything, nothing new can be acquired

Important Definitions #

Immutability (Immutabilitas) #

The divine attribute of being altogether unchangeable, grounded in God’s pure actuality and absolute simplicity. God’s unchangeableness distinguishes Him from all creatures, which can change either through their own potency or through dependence on God’s creative will.

Motion (motus) #

The act of what is able to be insofar as it is able to be (actus entis in potentia secundum quod in potentia). An imperfect act that is essentially incomplete—ceasing when the transition is complete. Contrasted with operation (operatio), which is a perfect act.

Operation (operatio) #

A perfect act or activity that is complete in itself and does not cease when occurring. Examples include understanding, seeing, loving, and willing. When engaged in operation, one has already completed the act.

Pure Act (Actus Purus) #

God’s mode of being, entirely actual without any passive potency or unrealized potential. This concept serves as the foundational “middle term” for understanding nearly all divine attributes.

Examples & Illustrations #

Composition and Change #

• Whiteness to Blackness: When something changes from white to black, the substance remains (what is white) while the accident changes. This composition is necessary for any change to occur.
• Butter Becoming Soft: It is not hardness itself that becomes soft, but the butter (the underlying subject) that loses hardness. This requires a real distinction between the butter and its properties.
• Baseball in Motion: When hit into the outfield, something must remain the same (the ball itself) throughout the motion. Without this unchanging subject, it would not be the same ball.

Distinction Between Motion and Operation #

• Walking Home: “When you’re walking home, have you walked home yet?” No—the action is incomplete. Only when you have walked home does the motion cease.
• Building a House: “When you’re building a house, have you built the house yet?” No—the motion is incomplete and exists only in the incompleteness.
• Seeing and Understanding: “When I’m seeing you, have I seen you yet?” Yes. “When I’m understanding what a triangle is, have I understood it?” Yes. These are perfect acts.
• Listening to Mozart: “I’m listening to Mozart” or “I’m thinking about God”—these are operations or doings. Though they seem restful, they are genuine activities, not mere passivity.

God’s Completeness #

• Retirement Question: When asked “What will you do when you retire?” responding “I will think about God” or “I will listen to Mozart” illustrates that perfect operations (operations) are genuine doings, even though they represent rest rather than motion in the strict sense.
• Guy Who Has Everything: If someone truly has everything, there is nothing new to give. Similarly, God, being infinite and containing all perfection, cannot acquire anything new through change.

The Reality of Motion vs. The Reality of Pure Act #

• Motion, though it appears real to us, is actually barely real: it consists mostly of past and future, with almost no presence in the now
• “When I walk out the door, my motion is mostly gone and to come. How much motion is there ever actually here? Well, in the now, I can’t be in two places. Is any motion in the now? There’s no motion in the now.”
• This explains why what seems most real to us (motion) is actually less real than what seems unreal (pure actuality), yet pure actuality is truly more real

Notable Quotes #

“God is pure act, right? What changes is able to be something other than it is, right? So there’s no ability in God in his passive sense, right? Therefore, he can’t change.”

“You begin to see that the thing that changes must be composed. And so when I teach that in philosophy of nature, I’ll say, now we can use this premise—but the premise in theology that God is not composed.”

“God is not composed. Therefore, God does not change.”

“I am God and I do not change.” (Malachi 3:6, cited as scriptural evidence)

“Everything that moves acquires something by its motion… But God, since he is infinite, comprehending in himself all the fullness or the perfection of the whole being, he’s not able to acquire something.”

“When I’m understanding what a triangle is, have I understood what a triangle is yet? Yeah. When I love somebody, I have loved them now.”

“My motion, in one sense, is hardly even present. Very, very, very fugitive kind of existence. And yet to us it seems to be the most real thing.”

Questions Addressed #

On the Apparent Objections to God’s Immutability #

Q: Doesn’t Augustine say that God moves Himself? A: Augustine speaks in the Platonic manner, using “motion” broadly for any operation or doing. When he says the Creator Spirit moves itself neither through time nor through place, he means God understands and loves Himself—perfect operations, not motion in the strict Aristotelian sense of imperfect act. This is a difference in terminology, not a real disagreement between Plato and Aristotle about the nature of the first principle.

Q: Doesn’t Scripture say wisdom is “more mobile than all mobile things” (Wisdom 7:24)? A: This refers to how divine wisdom diffuses its likeness through creation, step by step from highest to lowest things. It is not that divine wisdom itself moves, but rather that its effects and likenesses proceed through all creatures. The word “mobile” (or “moving”) is used metaphorically.

Q: How can God approach us if He doesn’t move (James 4:8: “Approach God, and he will approach you”)? A: These scriptural statements are metaphorical. Just as we say the sun “enters” our house when its rays arrive, God is said to “approach” us insofar as we perceive the influence of His goodness or “fall away” from it. The change is in us, not in God. God does not move toward us; rather, we experience His manifestation or withdrawal of His influence.

Q: Doesn’t change seem more real and vital than pure actuality? Isn’t God inactive if unchangeable? A: This reflects our tendency to imagine reality through motion. However, motion is actually barely real—consisting mostly of past and future with little presence in the now. Pure actuality is more real precisely because it lacks nothing and contains all perfection. Moreover, God does operate: He understands Himself and loves Himself—perfect operations. What God cannot do is acquire something new (which would require potency) or transition from incompleteness to completeness (which would require composition).

Pedagogical Notes #

The Role of Simplicity #

• The argument from composition to change depends on the prior establishment of God’s simplicity (from earlier lectures)
• The order of arguments matters: one can argue from pure actuality, then from simplicity, then from infinity—three arguments is sufficient
• Thomas uses this theological conclusion (God is simple and immutable) to illuminate a premise in the philosophy of nature (the changeable thing must be composed)

Understanding Equivocation #

• Students must grasp how Plato and Augustine extend the term “motion” to include perfect operations (understanding, loving)
• Aristotle, being more precise, distinguishes between imperfect acts (motion) and perfect acts (operation)
• This distinction is not merely terminological but reflects a genuine metaphysical insight about different kinds of actuality

Connection to Future Topics #

• At the end of the philosophy of nature course, the lecturer plans to return to God’s unchangeableness and introduce God’s eternity
• Eternity follows upon immutability just as time follows upon motion
• This requires understanding the definition of eternity in relation to the eternal now (nunc stans) versus the flowing now of time (nunc fluens)