Introduction
We think. That's obvious. But how often do we stop to fully appreciate the complexity of something as basic as a thought? How often do we ask ourselves: where does a thought actually come from?
Where Does Physics Come In?
At first glance, this might seem like a topic completely unrelated to physics. But I think that, at some scale, everything comes back to physics — because physics defines the universe itself. (I highly recommend reading my other nonsense about randomness here.)
The Objective View
According to physics, the universe is governed by a set of rules. A huge portion of these rules remains unknown to us, making the universe — and the future — unpredictable in practice. Also, quantum mechanics tells us that randomness exists at the very foundation of reality.
Could we say that even if the world is random, it’s still predetermined? Logically, no — true randomness breaks determinism. But when it comes to human experience, it doesn’t really matter. We — humans — are made of matter. And that matter is fully governed by physical laws, random or not.
Free Will
It’s a common belief that humans possess free will. But I think that idea is rather naive. However we look at it, there’s no obvious room for free will to exist. What we call "will" is just the behavior of our brain — and the brain, like everything else, is still just a system obeying physical laws.
While some events in the universe are random, they are independent of "us." We are simply a part of the universe — a very complicated, self-aware part — but still matter moving according to deeper rules.
Laplace’s Demon
In 1814, Pierre-Simon Laplace imagined a being — now called Laplace’s Demon — that, if it knew the precise position and velocity of every atom in the universe, could predict the entire past and future. In a fully deterministic world, this would be true. However, quantum mechanics (and chaos theory) destroyed this perfect determinism. Still, the idea shows just how mechanical the world could seem — and how little room it leaves for real "freedom."
Brain Experiments
Interestingly, neuroscience experiments also challenge our sense of free will. In the 1980s, Benjamin Libet showed that the brain starts preparing to make a decision milliseconds before the person becomes consciously aware of deciding. This suggests that what we call "decisions" might just be the brain informing our conscious mind about something it has already started doing.
Conclusions
In my opinion, we don't really have "free will" — at least not in the traditional sense. We are physical systems, governed by physical laws, influenced by randomness we cannot control. The "self" is an emergent process, not a separate free agent standing apart from the universe.
And even if free will is an illusion... maybe it’s better we believe in this illusion.
Before I ever read anything about this topic, I had no idea that the idea of free will's nonexistence was actually taken seriously in the scientific world. I had been thinking about it ever since I was a young child in primary school. Realizing now that it’s a real, serious idea — not just some private thought — is strangely joyful.