Atoms, Empty Space, and the Ghost in the Machine: Géraud de Cordemoy's Strange Universe

Imagine you’re holding a brick. You can’t see it, but that brick is made of tiny particles—atoms—that cannot be broken into smaller pieces. Between those atoms? Nothing. Pure empty space. Most people in the 1600s thought this was crazy. They believed matter could be divided forever, like cutting a piece of string in half over and over again, never reaching an end. And they believed empty space couldn’t exist—that if you tried to have a vacuum, the walls would just collapse inward.

But one French philosopher, Géraud de Cordemoy, looked at the world and came to a very different conclusion. He said: atoms are real, empty space is real, and here’s the really weird part—nothing in the physical world actually causes anything else to happen. Not one billiard ball hitting another. Not your hand moving when you want it to. All the real causing is done by God.

This is a story about how someone used pure logic to arrive at a universe that looks nothing like what our senses tell us.

What Is a Thing, Anyway?

Cordemoy started with a simple question: what does it mean for something to be a “substance”—a real thing that exists on its own? He borrowed from the philosopher René Descartes the idea that a substance is something that doesn’t need anything else to exist. A table needs wood, and wood needs atoms, but atoms—if they’re truly basic—don’t need anything else to be atoms. They just are.

Here’s where Cordemoy made a move that surprised everyone, including Descartes’ other followers. He said: if a body has parts, then it depends on those parts to exist. Take the parts away and the body disappears. So a body with parts can’t really be a substance. The only true physical substances, then, must be things that have no parts at all. They must be atoms—indivisible.

This is pure logic, not science. Cordemoy never looked through a microscope. He just sat in his study and thought: if substances can’t depend on anything else, and anything with parts depends on its parts, then real substances must be partless. Atoms.

But wait, you might say—I can see a brick, and it looks like one solid thing. Cordemoy would say that’s your senses fooling you. What you’re really seeing is a collection of billions of atoms packed close together. The brick isn’t one substance; it’s a crowd. He called collections like this “matter” and reserved the word “body” for the individual atoms themselves. Most people confuse the two, he said, because the atoms are too small to see.

Can There Be Nothing?

If you believe atoms are real, you also have to believe in empty space. Because if atoms are separate from each other, what’s between them? Something? No—the whole point is that atoms are the only physical substances. What’s between them must be nothing at all.

Cordemoy gave a simple thought experiment. Imagine three atoms in a row, touching each other. Now imagine the middle atom disappears instantly. What happens to the two outer atoms? Do they rush together to fill the gap? Cordemoy said no. Each atom is its own substance, independent of every other. Nothing forces them to move. So there’s just… empty space between them.

This seems commonsense to us now, because we’re used to the idea of a vacuum. But in the 1600s, most philosophers thought empty space was impossible. Descartes had argued that the nature of body is to take up space—so anywhere there’s space, there must be body. To have space without body was as impossible as having a smile without a face. Cordemoy disagreed completely. For him, space was just the distance between substances, not a thing in itself.

But Who Makes Things Move?

Here’s where Cordemoy’s philosophy takes its strangest turn. If you accept that atoms are simple substances, and that empty space exists, you still have to explain how anything moves. One atom bumps into another—the second moves. Simple, right?

Cordemoy said: not so fast.

He started with two observations. First, motion isn’t part of what a body is. A brick at rest is still a brick. If motion were essential to bodies, a still brick wouldn’t be a brick anymore. So motion is something a body has, not something it is. Second, you can’t actually hand motion from one body to another like passing a ball. Motion is a property, a “mode” of a body—it belongs to that body and that body alone. It can’t jump out of one atom and into another.

So what happens when you see one billiard ball hit another and the second one moves? Cordemoy said: you never actually see the causing. You see ball A move, then you see it touch ball B, then you see ball B move. But you never see the causing itself. You just assume there’s a cause-and-effect relationship because you see one thing followed by another.

He pushed this further. If bodies can’t cause motion in each other, and motion can’t be transferred, then where does motion come from? It has to come from something that can cause motion. But what kind of thing can do that? Not a body—we’ve already shown bodies can’t. That leaves only minds. Not your mind, though—because you can’t make your heart stop beating or regrow a lost limb by wishing it. And besides, Cordemoy said, when you think you make your hand move by willing it, you never actually observe the connection. You just see the willing and then the movement.

The only mind powerful enough to cause motion everywhere, at every moment, is God. Every time one atom appears to push another, God is actually doing the pushing. Every time you think “raise my hand” and your hand rises, God is the one moving it. The atoms and your body are just occasions for God to act.

This view is called occasionalism. It says that created things don’t really cause anything. They’re just the occasions on which God causes things.

Are Other People Real?

Cordemoy wrote an entire book about speech, and it starts with a deeply lonely question: how do I know there are other minds? I know I have thoughts and feelings. But you—the person reading this—might be a very sophisticated robot. You might be programmed to act exactly like a thinking person without actually thinking at all. How would I ever know the difference?

Cordemoy’s answer was language. Not just making sounds—parrots can do that. And not just responding to commands—a dog can learn to sit when you say “sit.” What matters, he said, is the creative, flexible use of signs to express thoughts. When someone says something they’ve never said before, in a way that fits the situation, that’s a sign they have a mind behind the words. No machine, no animal, no mere body could do that, he claimed. Only a thinking soul.

This might seem obvious to you, but think about how strange it is. You can never directly experience another person’s thoughts. You can only observe their behavior—their words, their facial expressions, their actions. Everything you know about other minds is an inference. Cordemoy was one of the first philosophers to really wrestle with that problem.

What’s Still Alive About This?

Cordemoy’s specific claims—atoms made of pure extension, empty space, God causing every motion—aren’t something many philosophers believe today. But the questions he raised are very much alive.

The problem of other minds hasn’t gone away. When you talk to an AI chatbot that sounds perfectly human, how do you know whether it’s conscious or just simulating consciousness really well? Cordemoy would say: pay attention to whether it says genuinely new things that fit the situation, or just spits back patterns it’s learned. But even that test might not settle it.

The problem of causation—what it even means for one thing to make another thing happen—is still debated. Physicists can describe how particles move, but they can’t point to the “causing” itself. David Hume, writing decades after Cordemoy, made the same observation: we see constant patterns, not causal glue.

And the question of whether minds are fundamentally different from bodies—whether there’s something special about consciousness that can’t be reduced to physical stuff—is one of the biggest debates in philosophy today. Cordemoy thought minds and bodies were completely different substances that couldn’t possibly interact without God’s help. Some modern philosophers agree that consciousness is mysterious and probably not physical. Others think we’ll eventually explain it in terms of brain activity. Nobody really knows.

Appendix

Key Terms

Term	What it does in this debate
Substance	A thing that exists on its own, not depending on anything else for its existence
Atom	A body with no parts, the smallest possible unit of matter
Matter	A collection of atoms; what we see when we look at ordinary objects
Mode	A property or state of a substance (like motion, shape, or position) that can change without the substance ceasing to be what it is
Occasionalism	The view that created things don’t really cause anything; they are just occasions for God to act
Void	Empty space with nothing in it
Plenum	A universe completely filled with matter, with no empty space

Key People

Géraud de Cordemoy (1626–1684): A French lawyer and philosopher who spent his time in Parisian intellectual circles, eventually becoming tutor to the son of King Louis XIV. He argued that the universe is made of indivisible atoms separated by empty space, and that God is the only real cause of motion.
René Descartes (1596–1650): The famous French philosopher who argued that mind and body are completely different kinds of things, and that the essence of body is extension (taking up space). Cordemoy borrowed many ideas from him but disagreed on atoms and empty space.
Dom Robert Desgabets (1610–1678): A fellow follower of Descartes who wrote a harsh letter arguing that Cordemoy’s atomism betrayed Descartes’ true philosophy and was logically impossible.

Things to Think About

If you believe that nothing can come from nothing, and that every event has a cause, do you have to trace that chain of causes back to something that caused the first thing? What would that something be?
Cordemoy said you never actually experience causation—you only see one thing happen after another. Think of three times today when you assumed something caused something else. In each case, what did you actually observe?
If you met a robot that could hold a conversation, tell jokes you’d never heard, and ask you questions about your feelings, would you believe it had a mind? Why or why not? How would you decide?
Cordemoy thought atoms were indivisible because otherwise they’d depend on their parts. But what if atoms are made of smaller particles, like quarks? Does that mean atoms aren’t “real” substances? What would Cordemoy say about quarks?

Where This Shows Up

The “other minds” problem appears every time you wonder whether an AI is conscious, or whether your dog has real thoughts and feelings, or whether your friends experience colors the same way you do.
The problem of causation shows up in arguments about whether free will exists (if every event is caused by previous events, where does choice fit in?) and in debates about what physics actually tells us about reality.
Atomism versus plenum is still a live question in physics: is space fundamentally empty (with particles moving through it) or is it a field full of energy at every point? Current physics leans toward the “field” view, but nobody knows for sure.