Here is Less Wrong's official policy on free will.
Free will is one of the easiest hard questions, as millennia-old philosophical dilemmas go. Though this impossible question is generally considered fully and completely dissolved on Less Wrong, aspiring reductionists should try to solve it on their own.
I encourage you to try solving the puzzle yourself before reading the rest of this spoilery post.
Quantum mechanics does not operate at the level of the human brain. The human brain is too big and too warm for quantum indeterminacy to matter. The human brain is a deterministic system. Every choice you make has already been predetermined by classical physics long before the decision reaches conscious awareness.
And yet—it feels like we have free will. As I type these words, it feels to me like I get to choose what to type.
What's going on?
Just because something feels real doesn't mean it actually is real. Many people hear disembodied voices. Many others feel like they're floating around outside their bodies. These experiences are hallucinations in the sense that the subjects' experiences conflict with what is actually occurring in the outside physical world. But the experiences are "real" in the sense that they represent real qualia and real internal physical brain states.
We tend to use the phrase "sound mind" to describe a state where your mind is functioning properly and your conscious experience is a correct model of reality. We use the inverse word "hallucination" to describe a state where your mind is malfunctioning and your conscious experience is a wrong model of reality. But those definitions are opposite corners of a 2×2 grid. They do not cover all possibilities. There are two corners unaccounted for. The illusion of free will describes a state where your mind is functioning properly even though your conscious experience is a wrong model of reality.
Most people feel like they have free will. But nobody actually does.
Then why do we feel like we have free will?
Some hallucinations are caused by malfunctioning wetware. But the illusion of free will isn't a malfunction—it's the human brain functioning as designed. If free will is by evolutionary design then there is a reason for it.
Why is the illusion of free will useful?
Because the human brain is a decision-making organ. It absorbs information and then decides what to do. Consider two brains competing at a fork in our evolutionary history.
- One mind knows that the universe is purely deterministic, that all of its actions are predetermined and that it cannot change the outcome of anything.
- Another mind believes (wrongly) that it has free will, that its conscious choices are not predetermined and that it can modify the universe via its actions.
What is going to happen when these organisms compete?
Keep in mind that these aren't modern human brains. They haven't been trained in philosophy or Newtonian physics. They might be fish brains from before our ancestors crawled out of the oceans onto land. They are much stupider than dogs and pigs.
The mind with (the illusion of) free will is more motivated to pursue goals.
The mind without (the illusion of) free will might fail to function at all.
Either way, the mind with (the illusion of) free will outcompetes the mind with an accurate model of the universe.
And we are descended from it.
Note: The "[REDACTED]" in the title was originally "a Useful Illusion" before I realized it spoiled everything.
At least—it used to feel that way before I did a bunch of meditation. Now I'm not so sure anymore. ↩︎