[jamestc]

He doesn't suggest that human nature is more than physics, he is saying that consciousness isn't computable. If neural subsystems are a hierarchically arranged and internally generated chaotic dynamic activity, there is the problem of long-term predictions and causal inference.

>It may seem paradoxical that a deterministic phenomenon is inherently unpredictable, but in systems that exhibit chaotic behavior, small uncertainties are amplified over time by the nonlinear interaction of a few elements. The upshot is that behavior that is predictable in the short run becomes intrinsically unpredictable in the long term. As a result, physiologists cannot make strict causal inferences from the level of individual neurons to that of neural mass actions, nor from the level of receptor activity to internal dynamics. The causal connection between past and future is cut.

http://sulcus.berkeley.edu/freemanwww/manuscripts/IC13/90.ht...

[Tichy]

That seems irrelevant to making a working brain thingy. We don't want to predict how another given brain will evolve, we want to mimic intelligence. Your brain evolves differently than mine, yet we both are intelligent (I think). I don't need to predict your thoughts to have thoughts of my own.

Perhaps the randomness is even necessary because otherwise some situations could never be resolved (like the classic who should go first to go through a door - after you - no, after you...).

[Filligree]

> Chaotic activity

Well yes, the brain is demonstrably chaotic.

Why does this matter? If you run a simulation of the brain, you'll soon get different output than the original would output, but does that mean the simulation isn't working?

It'll still be intelligent behaviour, even if it isn't the exact same behaviour. It'll still be the same person; if such behavioural differences mattered, then turning up the temperature slightly would make you a different person. Thermal noise bubbles up to the macroscopic level all the time.