Classicality – All in the mind?
David Pearce : The usual story runs something like this. The world and our minds are essentially classical. We don't see superpositions of alive-and-dead cats. Newton's laws of motion and inverse square law approximately hold for medium-sized objects. Macroscopic objects 1) occupy definite positions (the "preferred basis" problem) 2) don't readily display quantum interference effects; and 3) yield well-defined outcomes when experimentally probed. The classical macroworld seems to obey different rules from the quantum microworld.
However, perceptual direct realism is false. We need to distinguish the properties of the vehicle of our world-simulation from its content. Without phenomenal feature binding, there are no bound classical objects internal to our world-simulations that can be described by classical laws in the first instance. Compare how someone with simultanagnosia (cf.
Simultanagnosia - Wikipedia, the free encyclopedia) can see only one object at once. Or how someone with cerebral akinetopsia is "motion-blind". And these neurological syndromes involve only partial failures of phenomenal binding. In the case of total failure, we'd be akin to the skull-bound American minds in the experiment I discussed above. Whatever serial or (classically) parallel computations that skull-bound Americans collectively execute for the purposes of the experiment, all that exists phenomenally are 320 million discrete skull-bound "pixels" of experience, not a pan-continental subject of experience. By contrast - and over-simplifying - imagine a movie running at, say, 10 to the power 15 quantum coherent superpositions a second, i.e. not the synchronous firing of classical, macroscopically distinguishable neurons, but neuronal superpositions. What does it feel like to be such a "movie"?
An obvious response is that it doesn't feel like anything at all to instantiate a succession of quantum coherent neuronal superpositions that last femtoseconds or less. Consciousness, we tend to assume, arises only on a scale of milliseconds via (somehow) patterns of neuronal firings. But this response is _not_ a feasible answer if we assume (with Galen Strawson and others) that consciousness discloses the intrinsic nature of the physical. Indeed, the evidence that our minds are "what a quantum computer feels like from the inside" lies right under our virtual noses in the guise of the bound macroscopic classical objects of everyday experience.
I'd like to say that this is a prediction of the theory; but of course it's only a retrodiction. We'll know whether our minds are really quantum computers only when tomorrow's interferometry can probe the mind-brain at timeframes at which quantum coherent neuronal superpositions must occur. I say "must"; but such claim assumes that the unitary dynamics of quantum mechanics holds good in the mind-brain. Believers in "hidden variables" and dynamical collapse theories disagree.