Doctor Glyndwr wrote:
I'm not really concerned with the valildity of that comparison; more about the predictability of the human brain. Consider if I am wrestling with an important question, such as whether to vote Lib Dem, Conservative, or Labour in the general election. I lie awake all night turning it over in my mind, weighing up the pros and cons, and then in the morning I place a cross in a box.
The question is, could a hypothetical, sufficiently advanced observer who somehow could model my brain with perfect accuracy have told me at 9pm that night who I would vote for? It doesn't matter that such an observer doesn't exist. What matters is, if it did, and it can predict my response: where has my free will entered into it? When did I make a decision?
And if it cannot predict my response: why?
Of course, I don’t understand the machinations of the human brain. If I did, my knowledge would be considerably greater than the sum total of all of humanity in this respect, and I’d be one clever guy!
However, I speculate that the human brain is a complex, constantly evolving/changing (i.e. dynamic), chaotic and quasi-quantum system that cannot be compared to, say, a silicon based computer. If that’s true, then it is, by definition, impossible to model the precise, real time behaviour of an individual and that behaviour cannot, by implication be wholly repeatable, any more than the behaviour of weather systems is.
It wouldn’t matter how powerful our weather model was, even if to the last molecule of an entire global system, as such things are chaotic, ‘quantum like’ if you will – it all comes down to percentages and probabilities, and the longer time (T) is, the greater the deviation of the actual behaviour of the system from the ‘most probable’ pathway.
The brain is, as I’m quite sure you appreciate, a dynamic, constantly changing system, with neural pathways being made, destroyed and attenuated on a constant basis, triggered by actual thought processes/brain activity (and in this key sense, likenable to other chaotic, complex and dynamic systems like the weather). In using our brains, we change them constantly, this being the learning process. The same can hardly be true of a silicon CPU, of even the greatest complexity.
So in summary, I speculate that it is, in fact, impossible to predict the precise,
absolute ‘output’ of the human brain in your example, no matter how ‘perfect’ the modelling of it may be, for the inherent reasons stated. Furthermore, the irreducable margin of error would be directly proportional to the time elapse (T) from known, datum brain state (input stage) and the predicted output stage. One would, in fact, arrive at a series of possible outcomes with attendant probabilities, much like a weather forecast.
Your
actual quantum behaviour of neural firing hypothesis muddies the waters even more greatly, adding real, physical quantum variables into the mix. If that’s true, this would provide a firm, scientific basis for the brain behaviour, even based on our current paltry scientific knowledge and understanding, effectively an RNG function built into the brain! It would, of course, be impossible to talk in terms of absolute outcomes in any quantum sense; this isn’t how things work.
Besides all of the above, even if we were to consider the brain as a static, unchanging system that could actually be precisely modelled, even this does not inherently remove free will, as I contend in my earlier post. Just because someone’s behaviour is supposedly entirely predictable and repeatable does not necessarily mean that they have not exercised free will (discernment, judgement, conscience etc.), nor does it mean that their decision making process is only informed by fixed, inherited parameters such as genetic code alone.
Sadly, though, you do have less knowledge than people who have studied the chemistry behind the brain (Or been taught about it at uni - hello). The responses are complete, and over sufficient (Once a neuron is fired, it goes into positive feedback until it's completely finished, there's no such thing as a half fire) - and so alot more binary than you'd give them credit for - so there's going to be no real borderline case where quantum effects would play a noticable role. The entire "ooh, quantumness" argument is a bit of a fallacy based on not knowing, and wanting evidence to back up ones position.
You'd be best not turning to quantum mechanics to explain the brain. It doesn't work on that scale.
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