Further reading matter.

[zotz]

Yesterday there was a Guardian article about the philosopher (and sculptor, and jazz pianist, and sailor, and cidermaker . . .) Dan Dennett, who it turns out is a man too talented to be allowed to live. I have recommended his work to some of you before - especially Consciousness Explained and Darwin's dangerous Idea.

Comments

[steer.livejournal.com]

Otherwise we oculd just simutate in silico (and ab initio) every electron, proton and neutron in a human being together with their interactions, which is philosophically an entirely reasonable approach.

I agree -- but, as I have been saying, the most commonly accepted interpretations of QM are not simulable in such a way because of the problem of wave-function collapse. [You could say "just use a random number" -- but a computer cannot generate random numbers... I'm not being willfully obtuse here... this is rather the critical thing.]

[zoo-music-girl.livejournal.com]

Unsurprisingly, I don't agree.

1. We can easily introduce a stream of random numbers as an input - just time radioactive decays or summat. In the real world, therefore, we can surmount that argument trivially.

2. Neither do I accept that we have any reason to suspect that consciousness depends on individual quantum interactions in this way - in simulating mass action, we could just calculate the probability-weighted average for large numbers of interactions instead, if we prefer. For systems the size of a cell, it would work. We have no reason to suspect that fine-grained quantum phenomena are important in intelligence or consciousness.

3. You're diverging from Penrose's arguments here, I think, as that isn't the kind of noncomputability I believe he argues for (qv). If that was his objection he wouldn't have needed to drag gravity into it.

I think i had a fourth objection here, but I can't remember it. Maybe it'll come back to me.

[zotz]

Me again, of course . . .

[steer.livejournal.com]

We can easily introduce a stream of random numbers as an input

OK - you're already beyond Turing computable and using a probabilistic TM -- which is a superset of the TM. Now, next I ask you to consider Sum over Histories and eventually you are compelled (I hope) to accept that you in fact need a non deterministic TM -- which is a superset of the probabalistic TM. So, even if you dismiss Penrose as a harmless loony you are still compelled to admit that a real world simulation really requires something more than a TM. Penrose wants to take this a bit further and would require sim universe to require even more generalisation with his quantum gravity TM.

Neither do I accept that we have any reason to suspect that consciousness depends on individual quantum interactions in this way

I think I'm going to have no success convincing you either. I strongly suspect it myself but wouldn't call it a belief as such. I'm agnostic on the issue wavering towards belief.

You're diverging from Penrose's arguments here, I think, as that isn't the kind of noncomputability I believe he argues for

Certainly I'm diverging from his arguments. I'm pointing out that already the universe is noncomputable in the stricted TM sense and that this comes from QM. Therefore it is not any stretch of the imagination to say that a hypothetical theory of Quantum Gravity might include other more exotic forms of non-computability.