How atoms deviate and create the possibility of freedom
From Lesson 6 (Atoms and the Void), recall:
In the previous lesson, we learned that atoms have weight and naturally fall downward. But here's the puzzle: if every atom falls straight down infinitely through the void, they never collide. They never combine. Nothing ever forms. The universe is just a rain of atoms falling separately forever.
Yet we see a world of objects â plants, animals, rocks, stars. How did these form if atoms never meet?
Democritus didn't have a fully satisfying answer. Epicurus's solution changed philosophy forever.
Democritus, Epicurus's intellectual predecessor, established atomic theory but hit a logical wall. If atoms have only three properties (shape, size, weight) and all fall straight down by gravity, then:
This isn't just a physics problem. It's a problem about freedom. If everything is determined â if every atom's motion is fixed from eternity â then human choices are not truly free. You didn't choose to be born or to exist. Your thoughts and actions are just the inevitable consequence of prior atomic states.
Epicurus saw this clearly. A deterministic universe means no real responsibility, no real choice, no real ethics. It means fatalism. And fatalism is one of the great sources of human suffering.
If a man believes that nothing is in our power, he will not believe that anything is shameful or praiseworthy. Rather, he will think all things are fated and bound by necessity.
â Lucretius, based on Epicurus
The freedom problem:
If every event is caused by prior events infinitely backward, then your choices are not truly yours. You didn't cause your choices; they were caused by factors outside your control (prior atoms, prior events, genetic inheritance). You're a spectator of your own life, not an agent.
Ethical consequences:
Epicurus rejected this conclusion. He believed freedom was real, and his physics had to make space for it.
Epicurus proposed something radical: atoms don't always fall straight. At unpredictable moments, for no reason, an atom spontaneously swerves from its straight path â just a tiny deviation, but enough to change everything.
In Greek, he called this parenklisis (ĪÎąĪÎÎŗÎēÎģΚĪΚĪ). In Latin, Lucretius called it clinamen (the swerve). The swerve is:
When the atoms are moving straight down through the void by their own weight, at quite indeterminate times and places, they swerve a little from their course. So small is this swerve that we can scarcely speak of it.
â Lucretius, De Rerum Natura (Book II, lines 217-220)
Now atoms can collide:
The swerve is the key to everything: without it, there's no motion, no collision, no formation of objects, no life, no change. The entire universe depends on the swerve.
All atoms fall straight | No collisions | Nothing forms | Static universe
Some atoms swerve slightly | Collisions occur | Compounds form | Dynamic universe | Life possible
Uncaused vs. Random:
For Epicurus, an uncaused event means: not determined by prior atomic states. It's not "random" in the modern sense (where we have probability distributions). It's simply indeterminate â not caused, not determined, just happening.
How this enables freedom:
If every event is determined by prior causes, then "you" are just the inevitable result of prior atoms. Your choices follow necessarily from prior states. You're not really choosing.
But if some events are indeterminate (the swerve), then there's a break in the chain of necessity. Your choices don't follow necessarily from prior conditions. You have genuine options. You can act, and your action isn't predetermined.
The swerve makes freedom possible. Without it, fatalism rules.
Epicurus's swerve is an indeterministic physics. It breaks the causal chain that stretches back to infinity. Here's the crucial move:
If determinism is true: Every event, including every human choice, is determined by prior events. You didn't choose your genetics, your environment, your past. Those prior conditions determine what you choose now. Are you really free?
If indeterminism is true (via the swerve): Some events are not determined by prior causes. They just happen. The future is not fully determined by the past. You can make choices that are genuinely open â not forced by prior conditions.
Epicurus doesn't say your choices are random. Rather:
There is also something we must understand: that the soul has the greatest share in bringing about our safety and happiness. Understand that our soul, being made of very fine atoms, can swerve and affect our choices and actions.
â Epicurus (paraphrased by later Epicureans)
Modern quantum physics also discovered indeterminacy â the idea that the universe is not perfectly deterministic. Particles behave probabilistically, not predictably. This might seem to vindicate Epicurus.
But there's a difference. In quantum mechanics, indeterminacy is probabilistic â governed by probability waves and statistical laws. Epicurus's swerve is wholly uncaused â not governed by any law, not probabilistic, just spontaneous deviation.
Still, both break the deterministic chain. Both suggest that the future is genuinely open. In that sense, modern physics vindicated Epicurus's intuition: the universe is not a clockwork of fixed causes and effects.
The deep tension:
This question haunts philosophy even today. Modern compatibilists argue that freedom doesn't require indeterminism â you're free if you act on your own desires, values, and deliberation (even if those are ultimately determined). Others argue you need indeterminism (libertarian free will) â the swerve allowing genuine openness.
Epicurus's answer: The swerve is not "just happening" at the conscious level. Your mind deliberates, considers options, chooses. That deliberation is what it means to be free. The swerve at the atomic level enables this deliberation without it being predetermined. Your choice is genuinely yours because it's not forced by prior conditions.
This is subtle. The swerve doesn't make every choice random. It makes genuine choice possible. Once choice is possible, you're responsible for the choices you make.
Choose 2-3 of the following questions to explore. Click on a card to select it, then write your response below.
Does introducing randomness (the swerve) really solve the freedom problem? Or does it just shift the problem â now your choices are random instead of determined?
Some argue you're free only if your choices flow from your character and values. Others say you're free only if your choices aren't determined. Can both be true? What does Epicureanism suggest?
Quantum physics discovered real indeterminacy in the universe. Does this vindicate Epicurus? Or are quantum randomness and the swerve fundamentally different concepts?
If your choices are not determined, are you more or less responsible for them? Can you be responsible for something uncaused?
Epicurus's swerve is unobservable â it happens at the atomic level, too small to see. Is it really different from just saying "there's a cause we don't understand"?
When you make a choice, does it feel determined by your past? Or open and undetermined? What does introspection suggest about human freedom?
Test your memory on key concepts from earlier lessons.
Without looking back, write everything you can remember about:
The problem without the swerve:
Three characteristics of the swerve:
Swerve and human freedom:
Connection to ethics:
"I can explain the swerve, why it's necessary, and how it creates freedom and enables human agency."
Lesson 8: Soul, Mind, and Death â If the soul is made of atoms, then the soul is mortal. It disperses at death. We'll explore why this physics leads to Epicurus's famous argument: "Death is nothing to us."