On 15/07/2017 10:34 am, David Nyman wrote:
On 15 July 2017 at 00:46, Bruce Kellett <[email protected] <mailto:[email protected]>> wrote:On 15/07/2017 4:00 am, David Nyman wrote:ISTM, on reflection, that my tentative suggestion that the alternative cases are in some deeper sense 'unphysical' have some sort of explanatory force. It's circular of course, but not I think in a vicious way. IOW it would be the case that there just were no well-formed physical circumstances in which such encounters could occur.Well yes, that is what the singlet state means -- there are no physical circumstances in which the branches that form could violate QM. But that is a statement of the fact, not an explanation of that fact.Well, it's at least pointing in the direction of a mode of explanation in terms of a tight constraint on what could count as viably physical. Others have noted that physics (at least a physics adequate to support our kind of observer-hood) is suspiciously replete with such tight constraints. As I said, this would be a mystery if regarded merely as a brute given (i.e. it could simply have been otherwise) and hence it tends to point in the direction of a constraint on observational selection from a more general basis. And if so, it would of course then be the case that only appropriately-constrained phenomena, arising from such states of affairs as were physically capable of supporting observation, would thereby be observable.
I think that this is looking at it in the wrong way. Things can look very constrained and unnatural if you reverse the direction of explanation. If you take the physical world, with all its complexity, as the starting point, and then understand human consciousness as having evolved in this environment, then there is no real mystery to be explained.
ISTM however that any such notion implies a deeper level from which QM as we observe it gets 'selected' on what is essentially an anthropic (hate that term) basis.If you want to go down this route you still have to give an account of how this selection might come about -- why is it that violations of QM are fatal to consciousness?They would be fatal to consciousness if such violations precluded the formation of physical states of affairs adequate to comprise the vehicles of that consciousness and the environments on which their consistent experiences depended (as Brent has often noted).
I think Brent has commented that consciousness needs a world to be conscious of -- that doesn't, of itself, constrain that world in any way. Even more so if the consciousness is a product of evolution in that world. Evolution cannot produce anything that contradicts the laws of physics.
This in turn would imply that an entangled QM-physics is a prerequisite for (at least our species of) observation itself.Of course, if we hypothesise, on the basis of a computational theory of mind, that QM is indeed observationally selected from a deeper arithmetical level, then a 'canonical' physics of precisely this kind is indeed implied. In this scenario, computational continuations implying non-entangled encounters simply don't correspond to any of the observable 'physical worlds'.I have raised problems with the idea that consciousness "selects" specifically quantum behaviour in another thread. The basis of my worry with this is that there does not seem to be anything to rule out a purely Newtonian classical world exhibiting consciousness as we know it -- that is implied by substrate independence, strong AI, and the assumed ability to replace our consciousness with the equivalent computations carried out on a classical Turing machine. Hence quantum mechanics is not entailed by consciousness, so it is difficult to see how consciousness could select out specific facts about the world that were inconsistent with QM.But surely the counter-argument to that is that a truly Newtonian classical world wouldn't in fact be a viable physical world at all? For example, the Newtonian 'atom' would collapse more or less instantaneously.
A Newtonian classical world would not be our world explained in terms of purely Newtonian physics: it would be a world in which everything was explained by Newtonian and Maxwellian physics. So atoms would be solid entities interacting according to some force law -- not Rutherford atoms with a nucleus and surrounding electrons; stability questions would not arise. This world would be quite different from ours in many respects -- basically, as non-quantum, there would be no quantum effects. But Turing machines do not rely on quantum effects, so they could exist, and support consciousness, in such a world.
So what I'm suggesting is that consciousness in practice would have to depend on a physics actually capable of comprising its vehicles and their environments and that evidently such a physics, to be viable, must be quantum in nature.
I disagree. While quantum physics may be necessary to support our carbon-based form of biological life, there could be non-quantum life forms. Or, more particularly, classical Turing machine based consciousness, whether or not you wanted to consider that as a life form.
If so, this would likewise imply the observational selection of the necessary physics from a more general background.
But even if it did imply the observational selection of the results of quantum entanglement, you still have to give an account of how this comes about. Or else you are just relying on magic.
If CTM is assumed, this background would be computational and the corresponding physics would be comprised by the 1-person-plural appearance, via the FPI, of QM-like phenomena. On that assumption, Bruno attempts to demonstrate (pace the current state of your discussion with him on this) that the necessary quantum-like logic could in fact be derived from classical computation, in the kind of infinite limit entailed by the UDA. Or at least that the possibility of doing so has not yet been persuasively ruled out.
I think the possibility of non-quantum consciousness in a non-quantum world makes the success of this program less likely.
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