St. Thomas Aquinas’The Way of Motion

Thomas’ Proof from Motion

Potentiality Actuality

Change/Motion

The fulfillment of what exists potentially

The actualization of what exists potentially

(insofar as it exists potentially)

Examples of Change(in the widest possible sense)

Gaining weightGetting a suntanBecoming a doctorA meteor crashes to earthA shooting starRiding a bicycleLearning a tradeTeaching a concept

Potentiality Actuality

Agent cause

The agent cause is not only moving the block to its new form, he himself is moving or changing as he moves or changes the block.

Potentiality Actuality

The two are really different. Potentiality is NOT actuality.

Actuality is MORE than potentiality.

At restPotentially movingNot actually moving

At restPotentially movingNot actually moving

Nothing moves itself from potency to act, except by something already in act.

To say: “Nothing moves itself from potency to act, except by something already in act” is to say that “from nothing comes nothing”, or “one cannot get something from nothing”.

A thing cannot give what it does not have.

If a ball is at rest, it is NOT moving. It does not have motion. And so it cannot impart motion to itself.

A thing must receive a perfection that it does not have from something that actually has it.

The ball at rest receives motion from something actually moving.

Imagine a moving freight train that is infinitely long, one that has no engine.

Moving in this direction

Each one receives motion from a principle. The principle has something that is received by the one. The receiver initially has less.

The cause of motion in the receiver is the principle. The principle is the cause, and thus the explanation. The principle accounts for the motion. From something comes something.

If the series goes to infinity, then there is no principle, no cause, of the motion in the series. The whole series lacks a cause. We are expected to accept that each part on the series has a cause and explanation of its motion, but that the motion originally came from nothing, not something, and that the movement of the whole series lacks a cause. In other words, something came from nothing. The caboose moves, but there is no engine, no first cause of the movement.

But if there is no first cause of the movement, then the caboose does not move, in fact, it never moves. Neither does any freight car on the series move, for it is preceded by an infinite series.

To say that it moves, but that there is no first cause, is to say that potentiality and actuality are NOT different, that something can come from nothing, that something and nothing are the same thing, that potentiality and actuality are the same thing.

A terminal. An end.

Infinity means “without end”, “without term”. But one cannot divide infinity in half and speak of a series that is half infinite. If the motion comes to an end, then the series is not infinite. It is finite. Hence, there is a First Unmoved Mover or Principle.

Every part of the series is dependent, every part receives what it has from something, but the whole does not receive what it has.

The whole series is nothing but the sum of every part of the series. Every part of the series is dependent, but the whole is not dependent, but is independent.

The motion of every part of the series is explained and accounted for, and thus caused, but the whole series is uncaused and unaccounted for.

The motion of every part of the series comes from something, but the motion of the entire series comes from nothing.

An infinite series is both finite and infinite at the same time.

Contradictions

Hence, there is no infinite regress. There is not an infinite series of movers that precedes a moving thing. The series is finite.

If the series is finite, then there is a First Mover that is unmoved by anything prior to itself. If not, then this first mover is not absolutely first.

Hence, there is an Unmoved Mover, a mover that is unlike any mover within the series. For every mover within the series is a moved mover.

The Unmoved Mover is not moved in the act of moving.

The Unmoved Mover is not in a state of potentiality.