Let’s start with a basic idea that we can all agree on. Things change. Seasons come and go, seeds sprout into trees, and ideas go from “maybe” to “done.” Lets call that “motion” in the broad, classical sense. The key here is to recognize that something is always shifting from ‘potential’ to ‘actual’. And when a potential becomes actual, something has to do the ‘act’ of actualizing. For example wood cannot change itself from potentially hot to actually hot without outside help. These ideas led famed 13th century theologian Thomas Aquinas to state
“Whatever is in motion is moved by another.”
Now examine that statement by Aquinas. He is explaining the origin of change and motion. If, at this very moment, each mover only moves because something else is moved it, then we are looking at an ordered series, like a hand pushing a staff that pushes a stone. Every middle link is derivative. It borrows its power from something else.
But there in lies Aquinas’ genius. If you add more borrowed links of motion back forever, you still have nothing that originates motion. Like a ball rolling down the hill, one must ask “Who or what pushed the ball to roll in the first place?”. Without a first cause, a non-derivative source of motion, then nothing moves at all. That’s why an infinite regress does not work. Motion had to start somewhere.
So logically, if we want to make sense of why things change and move today, then there must be a first mover that moves other things without being moved by anything else. Aquinas identifies that first unmoved mover as God himself.
He argues that a first mover, must be a source and being of pure actuality. He must be unlimited potential itself with nothing left to add. That is the heart of the First Mover argument.
Here is a Quick Analogy
Imagine a freight train with hundreds of cars linked together and perfectly aligned. None of them move unless an engine car provides power to create that movement. Add ten more cars and you still have no motion without that engine. The First Mover is like that engine car.
Here are Some Common Objections
Objection 1: “This is outdated because modern physics has inertia and quantum randomness. Things move without needing a ‘pusher‘.”
Rebuttal 1: The argument is not about velocity or friction. It is about change itself as things move from potential to actual. That is a metaphysical question, not a physics one. Even if a particle’s behavior is probabilistic, the transition from “can happen” to “is happening” is still an actualization. The First Mover argument is about the need for an original source of actualization that explains why we have actualization here and now. You can keep every discovery from Newton to quantum theory and the point still stands.
Objection 2: Why can’t there be an infinite movers and just leave it at that?
Rebuttal 2: What we are dealing with is called the ‘ordered series’, which has what is called ‘simultaneous dependence’ in the present, where every atom and particle of energy in the entire universe borrows its causal role right now from something that happened in the past, and that something borrowed its causal role from something else, and so on and so on. If everything is borrowed with no original non-borrowed source, nothing can possibly move. Let me repeat that another way, an infinite stack of zeroes added together still equals zero. That is why a first, non-derivative mover is required.
Objection 3: Even if there is an unmoved mover, why call it God instead of a physical law or the universe itself?
Rebuttal 3: Laws describe how things behave, not what causes the behavior. You still need real things that obey the law, and those real things have potentials that get actualized. The first mover cannot be a bundle of potentials waiting to be actualized, or it would need a mover itself. It must be pure action incarnate, not composite, not limited, not subject to change. The First Mover is not just another object inside the universe. It is the foundational source that makes possible in the first place. That is why the argument points to what classical theism calls God, because it is the only logical source that could possibly be that first mover.
Final Thoughts
At the end of the day we all know that change is real. When we observe how this change works, it is a reasonable position to assume that there must be a first, original, non-borrowed source that moves things without being moved. That is the First Mover, which is God.
Now obviously this does not prove God entirely in one blog post, but it does add another plank to the bridge of evidence across that chasm.
That’s it for that lesson. If you are ready for the next one CLICK HERE.
-Will”