Comment by beloch | Hacker News Reader

Comment by beloch | Hacker News Reader

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"The original motivation in the early 20th century for relating quantum theory to consciousness was essentially philosophical. It is fairly plausible that conscious free decisions (“free will”) are problematic in a perfectly deterministic world,[2] so quantum randomness might indeed open up novel possibilities for free will. (On the other hand, randomness is problematic for volition!)"

This is an aspect of this debate that utterly fascinates me. Many people reading this have probably heard the argument that free will does not exist because the human brain is just a molecular computer. If we could measure it's state perfectly at a given moment, have knowledge of future inputs, and possess adequate classical computational power, we could perfectly predict the future decisions made by your brain. Hence, you are a deterministic creature with no free will.

Quantum processes underlie all classical processes, not unlike how the physics of individual water molecules underlie the behaviour of a river. While individual molecules or even drops of water can do bizarre things, the course of a river is easy to predict. A coin toss or weather patterns may seem random, but they're classical systems that would be utterly predictable if we had a perfect measurement of their current state, knowledge of input from outside the system in question, and the computational resources to work out their future evolution. As with a river, the weather, or a coin toss, quantum weirdness should average out on the scale of a human brain, leaving only classical predictability behind.

Or does it?

One aspect of this quantum weirdness I'm referring to is truly random behaviour. Single quanta (e.g. photons or atoms) can be manipulated to produce measurements with truly random results that are, according to quantum theory and every experiment conducted to date, impossible to predict, even with perfect knowledge of the system, knowledge of all inputs, and infinite computational resources. Free will and being unpredictable are intrinsically linked. If your brain is just a classical machine behaving according to the laws of chemistry and physics, you are predictable and have no free will. If your brain amplifies the results of quantum outcomes to a macroscopic level, your brain may be inherently unpredictable and thus you may possess free will.

Fascinating stuff!

> Free will and being unpredictable are intrinsically linked. If your brain is just a classical machine behaving according to the laws of chemistry and physics, you are predictable and have no free will. If your brain amplifies the results of quantum outcomes to a macroscopic level, your brain may be inherently unpredictable and thus you may possess free will.

But how do you address the last part of the quote you lead with ("randomness is problematic for volition")? How is your will any more free if it depends on random physical processes rather than deterministic ones?

The type of free will people often talk about is the type where if you rewind time to give you a second chance there is a potential for you to chose differently.

But whatever decision you want to make will ultimately be a function of your state of mind. How can you will something that isn't a result of your experiences? What else informs your will? The type of counter-causal free will people think they want probably doesn't exist.

You have free will, but it is determined. It's a result of physical processes. How we think may be difficult to computationally reduce, so it still might not be predictable. Counter-causal free will would force you to look outside the universe for causes. You get duality. Quantum randomness is not an escape for this.

Agreed. I would be no more assured that I had free will if you convinced me that there's a truly random factor in my decision making.

It seems kind of paradoxical. Either the universe is completely deterministic, in which case my decisions are already set in stone; or there's a truly random element, in which case my decisions might be probabilistic. Neither of these feels like free will.

I'm inclined to think of free will as a concept that is only meaningful in the context of higher-order abstractions. It's a facet of our internal monologue and interactions with other people. Asking whether humans fundamentally have free will seems like asking whether computers fundamentally have cursors.

At some point in the future, I could have a quantum random number generator implanted in my skull and defer many of my decisions to its outcomes. I wouldn't be predictable, but would I have free will? Probably not.

How our brains use quantum processes really is the heart of the debate, but we don't even know if they use quantum processes in a way that isn't averaged out at the level of neurons or our entire brain. If our brains do make use of quantum processes in a way that manifests at a macroscopic scale, that alone doesn't guarantee that we have free will, but it does open up that possibility. If our brains are classical, chemical computers, that possibility doesn't even exist.

This going pretty far out there in terms of imagination, but it seems possible something appearing random in our universe may not be random from another.

Yea it's crazy, but we already have theories from reputable physicists talking about stuff from other universes interacting with ours. I.E. of dark matter being the gravitational interaction of stuff from other dimensions.

So that's how it's theoretically possible randomness could sneak some free will into our universe. Far fetched, but I don't believe it's ruled out?

> If we could measure it's state perfectly at a given moment, have knowledge of future inputs, and possess adequate classical computational power, we could perfectly predict the future decisions made by your brain

This is not true even in principle.

Are you saying that with the assumption of a classical universe, or without?

I'm saying that with the assumption of a real universe, which doesn't behave classically.

I don't think OP was actually espousing that argument, just laying it out as context. I think most people in the thread are aware that we live in a universe that is fundamentally stochastic rather than deterministic.

Supposing you decide to buy a small coffee, but if some tiny probabilistic quantum interaction in your brain had gone another way, you'd have bought a medium sized coffee instead. Do you seriously believe a scenario like this constitutes free will? In a philosophically interesting sense?

I just don't see how randomness gains you the kind of "ghost in the shell" decision making that people usually mean when they're talking about this stuff. It's still just physical interactions, it just happens that these ones are fundamentally unpredictable.

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