If consciousness is fundamental, what predictions does it make?

“Scientists are explorers. Philosophers are tourists.”
(Richard Feynman)

The claim that consciousness is fundamental to reality is empirically adequate. It makes no novel predictions if taken on its own. If conjoined with physicalism, i.e. no “element of reality” is missing from the formalism of our best mathematical description of the universe, then the conjecture has stunning predictive power. Whether you regard the predictions as worth the trouble of experimentally falsifying via interferometry, or instead as the reductio ad absurdum of quantum mind, will depend partly on how seriously you take the phenomenal binding problem, not as just a puzzle for neuroscience, but as a challenge for monistic physicalism and the unity of science.

Any theory of consciousness, whether materialist or non-materialist, that makes no predictions that are (a) novel, (b) specific, (c) experimentally falsifiable and (d) agreed by proponents and critics can (dis)confirm its claims will most likely be scientifically worthless. Concretely, an adequate theory of consciousness should explain the (1) existence, (2) causal efficacy, (3) diversity and (4) phenomenal binding of subjective experience. However, unless empirically testable, the theory is almost certain to be idle philosophising. Not many theories of consciousness both satisfy the methodological constraints (a-d) of good science and give substantive answers (1-4). Molecular matter-wave interferometry can in principle test a “Schrödinger's neurons” conjecture that does both.

What will be the outcome of such an experiment?
I don’t know.
All the possibilities strike me as absurd.

One reason for playing around with crazy but testable hypotheses is that materialism has made no progress in solving the Hard Problem of consciousness since antiquity. If physicists and chemists are right about the fundamental properties of matter and energy, then we should be insentient: “p-zombies”. The empirical evidence reveals the universe has at least one sentient being. Alas there may be others. Therefore, physicists and chemists don’t really understand matter and energy.

Post-materialist science must explain the successes of the old paradigm as well as its failures and anomalies, in this case the empirical evidence. The intrinsic nature argument for non-materialist physicalism proposes that our phenomenal minds disclose the intrinsic nature of the physical. So the Hard Problem (1) is just an artefact of bad metaphysics – as distinct from the mystery of why anything exists at all. According to non-materialist physicalism, the mathematical machinery of quantum field theory (QFT) captures the structural-relational properties of matter and energy. The formalism describes fields of sentience rather than insentience. In other words, the entire mathematical apparatus of modern physics is transposed to an idealist ontology. Philosopher Galen Strawson calls the conjecture “Real Materialism” – although this tongue-in-cheek label must count as poetic license.

Non-materialist physicalism should be distinguished from property-dualist panpsychism. Non-materialist physicalism doesn’t claim that consciousness is inseparably associated with physical properties. Rather, consciousness is the physical: the primordial “fire” in the field-theoretic equations, what Kant called the noumenal essence of the world, at once unknown and supposedly unknowable. Thus if non-materialist physicalism is true, then ill-named p-zombies don’t exist precisely because they are unphysical. Only the physical is real. Likewise, the reason that consciousness has the causal capacity (2) to e.g. discuss its own existence is that all the physical, and only the physical, has causal efficacy. As posed, the palette problem (3) presupposes classical physics. The rich diversity of conscious experience is mysterious in the light of the relative qualitative homogeneity of your brain's basic constituents as normally described. Yet according to modern physics, quantum fields, not particles, are fundamental to reality. According to the quantum-theoretic version of the intrinsic nature argument, the diverse solutions to the equations of QFT yield the diverse values of experience. Hypothetical fields of insentience are doomed to go the way of luminiferous aether.

What about phenomenal binding (4)? The intrinsic nature argument for non-materialist physicalist has two variants. The first variant, associated with e.g. Galen Strawson and most recently Phil Goff, is effectively classical. Billions of decohered, membrane-bound neurons in our skulls are simply assumed (rather than derived via the decoherence program from QFT). Our minds are just what patterns of excitation in neural networks feel like “from the inside”. The classical variant of the intrinsic nature argument has two problems. It cannot solve the phenomenal binding / combination problem. So it doesn’t demystify why (unless dreamlessly asleep) we aren’t micro-experiential zombies. Worse, the classical version of the intrinsic nature argument isn’t experimentally falsifiable. It makes no novel testable predictions over-and-above “materialist” physicalism.

The second, quantum-theoretic variant of the intrinsic nature argument satisfies the methodological criteria (a-d). However, its predictive novelty doesn’t rest on some new principle of physics, such as a consciousness-induced “collapse of the wavefunction”. Rather, the quantum-theoretic version focuses on what non-materialist physicalism entails for the CNS. If consciousness discloses the intrinsic nature of the physical, then the fundamental “psychon” of consciousness must indeed be untestably small, as incredulous critics of traditional panpsychism have long stressed. But a less-discussed implication is that if consciousness discloses the intrinsic nature of the physical, then the psychon must also be insanely short-lived. What does such a short, sub-femtosecond effective lifetime entail for the microstructure of the CNS? Let’s assume quantum theory is complete, i.e. just the bare formalism of QM, unmodified and unsupplemented. At sufficiently fine-grained temporal resolutions, your central nervous system does not consist of decohered neurons – mere classical aggregates of mind-dust – but rather, individual “cat states”, i.e. neuronal superpositions of the distributed feature-processors (e.g. neuronal edge-detectors, motion-detectors, colour-mediating neurons and so forth) as identified by conventional neuroscanning. According to unitary-only quantum mechanics, all complex linear superpositions of pure states must exist. If such rapidly-decohering neuronal superpositions don’t exist, then the cardinal principle of quantum mechanics, i.e. the superposition principle, is false. What’s more, the quantum-theoretic version of the intrinsic nature argument invokes an extraordinarily powerful selection mechanism to explain why we don’t experience just psychotic nonsense, or most of us at any rate. The selection mechanism explains why the comparatively dynamically stable neuronal superpositions subjectively experienced as our classical world-simulations are differentially favoured over dynamically unstable psychotic “noise”. What Zurek christened “quantum Darwinism” is now mainstream physics. The decoherence program (Zeh, Zurek, et al.) describes the emergence of quasi-classicality from quantum reality outside the skull, but needs applying to the CNS. We may be shocked. Once again, I don’t know. I’m simply curious.

Theorists working on the foundations of quantum mechanics point out that the decoherence program doesn’t solve the problem of definite outcomes. But on the “Schrödinger's neurons” conjecture explored here, there are no definite classical outcomes, merely neuronal superpositions experienced as definite outcomes. Only the universality of the superposition principle makes our fitness-enhancing experience of classical definite outcomes feasible. To experience a definite outcome, for example a determinate pointer-reading or a live cat, you need non-psychotic binding; and binding is classically impossible.

Objections? I guess the reason that most of the scientific community (and Wikipedia editors) would dismiss such a conjecture without waiting for experimental disconfirmation isn’t because such a theory invokes a speculative new principle of physics like the Penrose-Hameroff Orch-OR theory. Rather, the dismissal stems from a commonsense philosophical assumption, namely that the sub-femtosecond timescale of neuronal superpositions makes such theoretical quantum exotica irrelevant to our mental life. See Max Tegmark on the “dynamical timescales” objection. Yet the intrinsic nature argument isn’t a conjecture about dynamical timescales. As the name suggests, it’s a proposal about the intrinsic nature of the quantum states that constitute our minds. True or false, the proposal stands irrespective of whether we calculate that the effective theoretical lifetime of neuronal superpositions in the CNS must be picoseconds, femtoseconds, attoseconds – or less(!). The subjective content of these neuronal superpositions – the frames of your experiential life movie, if you like – consists of our robustly classical-seeming waking world-simulations. The gross subjective content of our world-simulations typically updates over a timescale of scores of milliseconds, i.e. the dynamical timescale described by classically parallel connectionist neuroscience. Yet though the subjective content is classical, the vehicle of our minds is inescapably quantum. If the superposition principle broke down in your skull, then subjectively classical unified world-making would be impossible. If neurons were decohered classical objects, then you wouldn’t be able to experience phenomenally-bound perceptual objects populating your phenomenally-unified virtual world.

Yes, crazy stuff. I can’t seriously believe it. However, this is an empirically falsifiable conjecture. At worst, the loophole should be experimentally closed. If classically unexplained binding via synchrony is actually binding by coherent superposition, then the non-classical interference signature of molecular matter-wave interferometry will tell us. Instead of the partial structural match in the CNS revealed by conventional neuroscanning, the non-classical interference signature will disclose a perfect match: a perfect structural match not in classical four-dimensional spacetime, but the fundamental high-dimensional space required by the dynamics of the wavefunction.

And what if interferometry discloses nothing but “noise”? If your intuition says that a negative result is overwhelmingly likely, well, mine does too. Yet if (1) phenomenal binding is classically impossible, and (2) the non-classical interference signature does not disclose a perfect structural match between our minds and the microstructure of CNS, then dualism is true, just as David Chalmers argues. Or eliminativism, which would solve all our problems.