Consciousness and Quantum Theory: Twelve Cautions
Recent empirical findings have lent credence to a suggestion first put forward by Roger Penrose and Stuart Hameroff that consciousness arises from reductions of quantum states in microtubules in the brain.[1] Their proposal is one of a number that have been advanced since Niels Bohr and others responsible for the early development of quantum theory speculated that the phenomena of entanglement and complementarity might be relevant to explaining the mind-brain relation.[2] An excellent survey of the background to, and varieties of, quantum theory approaches to consciousness is given in Harald Atmanspacher’s article on the subject in The Stanford Encyclopedia of Philosophy.[3] The Penrose-Hameroff proposal is known as the ‘Orch Or Theory’ (OOT, orchestrated objective reduction of the quantum state), and the recent empirical findings supporting it come from work in anaesthetics research; Hameroff is himself an anaesthesiologist. A paper by a team at Wellesley College has been widely reported as giving reason to think that quantum effects at the microtubule level is a promising domain for consciousness research, as evidenced by the delay in the onset of unconsciousness in experimental animals caused by administration of a microtubule-stabilising drug.[4]
Although OOT requires a yet-to-be-developed theory of quantum gravity to support the idea of a quantum state reduction of the kind Penrose and Hameroff propose, these findings strongly suggest that the direction of travel they indicate might be the right one. If so, it is an exciting and important development. In light of the explanatory and applications power of quantum theory, there is reason to think that we (humanity, i.e.) are on the brink of a major breakthrough in one of the most puzzling and difficult problems confronting science and philosophy.
To sound a note of caution from epistemology might seem a little grudging, but considerations from the history of ideas, and the challenges that face enquiry in almost every field, together suggest that, nevertheless, we do well to temper over-enthusiasm until we are in a confident position to set aside the cautions they offer.
The history of ideas tells us that the adoption of a model for analogising or explaining puzzling phenomena is a natural and ready resource in the quest for understanding them. To take just a few: at the beginning of the modern period (15th-16th centuries) the miniaturisation of clockwork provided a model for thinking about the way the human body, indeed the entire universe, works. In the late nineteenth century, telephone exchanges provided a model for thinking about the central nervous system. In the mid-twentieth century (in this case considerably more improbably) space flight suggested that the gods might be aliens who visited Earth and communicated ideas and traditions to humankind. In the same period the idea that the brain is a computer proved highly attractive.
We now see the unintuitive and complex realm of quantum phenomena offering a location for understanding consciousness and free will. Prompted by the history of earlier models, one considers the possibility that current quantum theory and its hoped-for extension into theories of quantum gravity is not the final stage of understanding physical reality, but is a staging-post to deeper and more inclusive theories, perhaps successions of such, that will involve regarding current quantum theory as an approximation, or special case, or perhaps even a misleading first pass, in the way that relativity supersedes classical physics and quantum theory supersedes the first theories of the atom. If this were so, it would turn out that explaining consciousness by invoking quantum effects at an empirically-accessible level (neuronal microtubules) was, at best, a first pass in the same way – and perhaps not the right way at all. As with earlier models, this too might take its place in the museum of ideas.
The challenges of enquiry are even more pertinent. In summary (I explain and apply them more fully in a recent book[5], using the labels there coined or borrowed) they are as follows.
The Pinhole Problem. Our starting point in all enquiries is the limited and highly circumscribed data available to us locally in space and time as cognitive agents of our scale and endowments, from this finite point of view allowing us a view of the universe as if through a pinhole positioned at just our restricted point, our current thinking about physical reality (from the Planck dimensions to the diameter of the universe) being as far as we can currently reach, by theory, from the pinhole. Do our methods successfully carry us through and beyond the pinhole in any case?
The Metaphor Problem. What metaphors and analogies are invoked to make sense of what these enquiries are telling us, and might they mislead?[6]
The Map Problem. What is the relation between theories and the realities, or at least subject-matters, they address, given the analogous differences between a map and the terrain it represents in approximated miniature?
The Criteria Problem. What are the justifications and, where necessary, correctives for the application of criteria such as ‘simplicity’, ‘optimality’, ‘adequacy’, even ‘beauty’ and ‘elegance’, in the formulation of research programmes and approval of results? Do appeals to extra-theoretical criteria help or distort enquiry?
The Truth Problem. Given that empirical enquiry gives us defeasible probabilities, what are the standards (such as the sigma scale in science) that can be regarded as satisfactory short of certainty? Does this imply that we have to treat the concept of truth pragmatically, as a (possibly unattainable) goal of enquiry upon which, in the ideal, enquiry strategically converges? Where does this leave the concept of ‘truth’ itself?
The Ptolemy Problem. Ptolemy’s geocentric model of the universe ‘worked’ in a number of ways, permitting the successful navigation of oceans and prediction of eclipses, thus showing that a theory can be efficacious in some respects while still being incorrect. How do we avoid being misled by pragmatic adequacy? A similar example is the efficacy claimed for some applications of acupuncture, a practice based on notions of ‘qi’ and meridian lines, for which no physiological or histological evidence exists.
The Hammer Problem. Summed up pithily as ‘If your only tool is a hammer, everything looks like a nail’, this reminds us that we tend only to see what our methods and equipment are capable of revealing to us.
The Lamplight Problem. One searches for one’s lost keys under the street lamp where one can see. We enquire into what is accessible to enquiry, for the obvious reason that we cannot access what is inaccessible.
The Meddler Problem. Investigating and observing can affect what is being investigated or observed. In studying animals in the wild, is one studying them as they would be if unobserved, or is one studying behaviour influenced by their being observed (the ‘Observer Effect’)? Similarly, can the disruption caused by slicing and staining a specimen for microscopic examination be reliably excluded? Can smashing subatomic particles together reliably reveal how they are constituted?
The Reading-in Problem. Interpretations of data are frequently made according to assumptions local in time and experience to the investigators. This is a feature of the employment of best-available models as exemplified in the history of ideas.
The Parmenides Problem. Reducing everything to a single ultimate causal or explanatory principle is taken as a goal or at least ideal of enquiry, as exemplified in the ambitions of fundamental science. Might this ambition mislead if complexity in the phenomena is irreducible?
The Closure Problem. This is the desire to reach a conclusion, to have a completed explanation or story, to tidy up and sign off. It is a natural human impulse to have satisfying narrative-style explanations, ‘this because that’ where ‘that’ does the job of terminating the explanatory chain. (Arguments to the ‘best explanation’ and appeals to a ‘god of the gaps’ provide classic examples.)
Reflection on these challenges, which in disciplined ways are met or at least mitigated by the most scrupulous methods of research, suggests that quantum theory itself, and a fortiori its invocation to explain consciousness, faces all of them. Quantum theory’s power is evidence that the required mitigations are always sought by researchers, the overwhelmingly strong evidence provided by nuclear power generation and the destructiveness of nuclear weapons in favour of theories of the structure of the atomic nucleus and the principle of the equivalence of mass and energy effecting closure on ‘Ptolemy Problem’ scepticism, lowering to near zero the latter’s sigma value. Yet the persistent sceptic, in light of its conjunction with the other challenges, might refuse to regard the closure as total.
And that refusal applies to quantum theory itself; the inference to its role in the generation of states of consciousness is another and far further step without nearly the same probative value in current theory. Here the sceptic will point immediately at the consideration that the empirical date invoked – in the cited case the effect of Epothilone B on neuronal microtubule activity in rats – is a correlation ‘only’.
If nothing else, keeping enquiry’s challenges in mind is salutary, and if the current state of fundamental theory turns out to be a staging-post to something else, perhaps with the consequence that quantum effects in microtubules are not the basis of consciousness, it will not change the fact that creative and innovative research on the basis of best available theory was justified, just as the seventeenth century clockwork model and the late nineteenth century telephone exchange model gestured at something right in their respective spheres.
[1] Penrose, R., 1989, The Emperor’s New Mind, Oxford: Oxford University Press.;1994, Shadows of the Mind, Oxford: Oxford University Press; Hameroff, S.R., and Penrose, R., 1996, “Conscious events as orchestrated spacetime selections,” Journal of Consciousness Studies, 3(1): 36–53.
[2] See e.g. the discussions in Suarez, A., and Adams, P. (eds.), 2013, Is Science Compatible with Free Will?, Berlin: Springer.
[3] Atmanspacher, H., ‘Quantum Approaches to Consciousness’, The Stanford Encyclopedia of Philosophy, revised 2024 https://plato.stanford.edu/entries/qt-consciousness/#QuanBrai retrieved 27.9.24.
[4] Khan, S., et. al. ‘Microtubule-Stabilizer Epothilone B Delays Anesthetic-Induced Unconsciousness in Rats’ eNeuro 15 August 2024, 11 (8) ENEURO.0291-24.2024; https://doi.org/10.1523/ENEURO.0291-24.2024 retrieved 27.9.24.
[5] Grayling, A. C., 2021, The Frontiers of Knowledge, Viking Penguin, pp. 7-9 and passim.
[6] See Grayling, A. C., ‘Introduction’ to Grayling, A. C. and Wuppuluri, S., eds., 2022, Metaphors and Analogies in Sciences and Humanities, Synthese Library vol. 453, Springer and Grayling, A. C., forthcoming, The Metaphysics of Experience ‘Metaphor’ chapter 5 passim.