Wendt's strong claims about quantum consciousness

Alex Wendt takes a provocative step in Quantum Mind and Social Science: Unifying Physical and Social Ontology by proposing that quantum mechanics plays a role in all levels of the human and social world (as well as all life). And he doesn't mean in the trivial sense that all of nature is constituted by quantum-mechanical micro-realities (or unrealities). Instead, he means that we need to treat human beings and social structures as quantum-mechanical wave functions. He wants to see whether some of the peculiarities of social (and individual) phenomena might be explained on the hypothesis that mental phenomena are deeply and actively quantum phenomena. This is a very large pill to swallow, since much considered judgment across the sciences concurs that the macroscopic world — billiard balls, viruses, neurons — are on a physical and temporal scale where quantum effects have undergone “decoherence” and behave as strictly classical entities.

Wendt’s work rests upon a small but serious body of scholarship in physics, the neurosciences, and philosophy on the topics of “quantum consciousness” and “quantum biology”. An earlier post described some tangible but non-controversial progress that has been made on the biology side, where physicists and chemists have explored a possible pathway accounting for birds’ ability to sense the earth’s magnetic field directly through a chemical process that depends upon entangled electrons.

Here I’d like to probe Alex’s argument a bit more deeply by taking an inventory of the strong claims that he considers in the book. (He doesn’t endorse all these claims, but regards them as potentially true and worth investigating.)

1. Walking wave functions: "I argue that human beings and therefore social life exhibit quantum coherence – in effect, that we are walking wave functions. I intend the argument not as an analogy or metaphor, but as a realist claim about what people really are. (3) ... "My claim is that life is a macroscopic instantiation of quantum coherence. (137) ... "Quantum consciousness theory suggests that human beings are literally walking wave functions. (154)
2. "The central claim of this book is that all intentional phenomena are quantum mechanical. (149)  ... "The basic directive of a quantum social science, its positive heuristic if you will, is to re-think human behavior through the lens of quantum theory. (32)
3. "I argued that a very different picture emerges if we imagine ourselves under a quantum constraint with a panpsychist ontology. Quantum Man is physical but not wholly material, conscious, in superposed rather than well-defined states, subject to and also a source of non-local causation, free, purposeful, and very much alive. (207)
4. "Quantum consciousness theory builds on these intuitions by combining two propositions: (1) the physical claim of quantum brain theory that the brain is capable of sustaining coherent quantum states (Chapter 5), and (2) the metaphysical claim of panpsychism that consciousness inheres in the very structure of matter (Chapter 6). (92)
5. Quantum decision theory: "[There is] growing experimental evidence that long-standing anomalies of human behavior can be predicted by “quantum decision theory.” (4)
6. Panpsychism: "Quantum theory actually implies a panpsychist ontology: that consciousness goes “all the way down” to the sub-atomic level. Exploiting this possibility, quantum consciousness theorists have identified mechanisms in the brain that might allow this sub-atomic proto-consciousness to be amplified to the macroscopic level. (5)
7. Consciousness: "The hard problem, in contrast, is explaining consciousness. (15) ... "As long as the brain is assumed to be a classical system, there is no reason to think even future neuroscience will give us “the slightest idea how anything material could be conscious.” (17) ... "Hence the central question(s) of this book: (a) how might a quantum theoretic approach explain consciousness and by extension intentional phenomena, and thereby unify physical and social ontology, and (b) what are some implications of the result for contemporary debates in social theory? (29)
8. The quantum brain: "Quantum brain theory hypothesizes that the brain is able to sustain quantum coherence – a wave function – at the macro, whole-organism level. (30) ... "Quantum brain theory challenges this assumption by proposing that the mind is actually a quantum computer. Classical computers are based on binary digits or “bits” with well-defined values (0 or 1), which are transformed in serial operations by a program into an output. Quantum computers in contrast are based on “qubits” that can be in superpositions of 0 and 1 at the same time and also interact non-locally, enabling every qubit to be operated on simultaneously. (95)
9. Weak and strong quantum minds: "In parsing quantum brain theory an initial distinction should be made between two different arguments that are often discussed under this heading. What might be called the “weak” argument hypothesizes that the firing of individual neurons is affected by quantum processes, but it does not posit quantum effects at the level of the whole brain. (97)
10. Vitalism: "Principally, because my argument is vitalist, though the issue is complicated by the variety of forms vitalism has taken historically, some of which overlap with other doctrines. (144)
11. Will and decision: "In Chapter 6, I equated this power with an aspect of wave function collapse, viewed as a process of temporal symmetry-breaking, in which advanced action moves through Will and retarded action through Experience. (174) ... "Will controls the direction of the body's movement over time by harnessing temporal non-locality, potentially over long “distances.” As advanced action, Will projects itself into what will become the future and creates a destiny state there that, through the enforcement of correlations with what will become the past, steers us purposefully toward that end. (182)
12. Entangled people: "It is the burden of my argument to show that despite its strong intuitive appeal, the separability assumption does not hold in social life. The burden only extends so far, since I am not going to defend the opposite assumption, that human beings are completely inseparable. This is not true even at the sub-atomic level, where entangled particles retain some individuality. Rather, what characterizes people entangled in social structures is that they are not fully separable. (208-209)
13. Quantum semantics: "This suggests that the “ground state” of a concept may be represented as a superposition of potential meanings, with each of the latter a distinct “vector” within its wave function. (216)
14. Social structure: "If the physical basis of the mind and language is quantum mechanical, then, given this definition, that is true of social structures as well. Which is to say, what social structures actually are, physically, are superpositions of shared mental states – social wave functions. (258) ...  "A quantum social ontology suggests – as structuration theorists and critical realists alike have long argued – that agents and social structures are “mutually constitutive.” I should emphasize that this does not mean “reciprocal causation” or “co-determination,” with which “mutual constitution” is often conflated in social theory. As quantum entanglement, the relationship of agents and social structures is not a process of causal interaction over time, but a non-local, synchronic state from which both are emergent. (260) ... "First, a social wave function constitutes a different probability distribution for agents’ actions than would exist in its absence. Being entangled in a social structure makes certain practices more likely than others, which I take to involve formal causation. (264-265)
15. The state and other structures: "The answer is that the state is a kind of hologram. This hologram is different from those created artificially by scientists in the lab, and also from the holographic projection that I argued in Chapter 11 enables us to see ordinary material objects, since in these cases there is something there visible to the naked eye. (271) ... Collective consciousness: "A quantum interpretation of extended consciousness takes us part way toward collective consciousness, but only part, because even extended consciousness is still centered in individual brains and thus solipsistic. A plausible second step therefore would be to invoke the concept of ‘We-feeling,’ which seems to get at something like ‘collective consciousness,’ and is not only widely used by philosophers of collective intentionality, but has been studied empirically by social psychologists as well. (277)

In my view the key premise here is the quantum interpretation of the brain and consciousness that Alex advocates. He wants us to consider that the operations of the brain -- the input-output relations and the intervening mechanisms -- are not "classical" but rather quantum-mechanical. And this is a very, very strong claim. It is vastly stronger than the idea that neurons may be affected by quantum-level events (considered in an earlier post and subject to active research by people interested in how microtubules work within neurons). But Alex would not be satisfied with the idea that "neurons are quantum machines" (point 9 above); he wants to make the vastly stronger argument that "brains are quantum computers". And even stronger than that -- he wants to claim that the brain itself is a wave function, which implies that we cannot understand its working by understanding the workings of its (quantum) components. (I don't think that computer engineers who are designing real quantum computers believe that the device itself is a wave function; only that the components (qubits) behave according to quantum mathematics.) Here is his brain-holism:

Quantum brain theory hypothesizes that quantum processes at the elementary level are amplified and kept in superposition at the level of the organism, and then, through downward causation constrain what is going on deep within the brain. (95)

So the brain as a whole is in superposition, and only resolves with perception or will as a whole in an event of the collapse of its wave function. (He sometimes refers to "a decoherence-free sub-space of the brain within which quantum computational processes are performed" (95), which implies that the brain as a whole is perhaps a classical thing encompassing "quantum sub-regions".) But whether it is the whole brain (implied by "walking wave function") or a relatively voluminous sub-region, the conjurer's move occurs here: extending known though kinky properties of very special isolated systems of micro-entities (a handful of electrons, photons, or atoms) to a description of macro-sized entities maintaining those same kinky properties.

So the "brain as wave function" theory is very implausible given current knowledge. But if this view of the brain and thought cannot be made more credible than it currently is -- both empirically and theoretically -- then Wendt's whole system falls apart: entangled individuals involved in structures and meanings, life as a quantum-vital state, and panpsychism all have no inherent credibility by themselves.

There are many eye-widening claims here -- and yet Alex is clear enough and well-versed enough in relevant areas of research in neuroscience and philosophy of mind to give his case some credibility. He lays out his case with calm good humor and rational care. Alex relies heavily on the fact that there are difficult unresolved problems in the philosophy of mind and the philosophy of physics (the nature of consciousness, freedom of the will, the interpretation of the quantum wave function). This gives impetus to his call for a fresh way of approaching the whole field -- as suggested by historians of science like Kuhn and Lakatos. However, failing to reach an answer to the question, "How is freedom of the will possible?", does not warrant us to jump to highly questionable assumptions about neurophysiology.

But really -- in the end this just is not a plausible theory in my mind. I'm not ready to accept the ideas of quantum brains, quantum meanings, or quantum societies. The idea of entanglement has a specific meaning when it comes to electrons and photons; but metaphorical extension of the idea to pairs or groups of individuals seems like a stretch. I'm not persuaded that we are "walking wave functions" or that entanglement accounts for the workings of social institutions. The ideas of structures and meanings as entangled wave functions (individuals) strike me as entirely speculative, depending on granting the possibility that the brain itself is a single extended wave function. And this is a lot to grant.

(Here is a brief description of the engineering goals of developing a quantum computer (link):

Quantum computing differs fundamentally from classical computing, in that it is based on the generation and processing of qubits. Unlike classical bits, which can have a state of either 1 or 0, qubits allow a superposition of the 1 and 0 states (both simultaneously). Strikingly, multiple qubits can be linked in so-called 'entangled' states, in which the manipulation of a single qubit changes the entire system, even if individual qubits are physically distant. This property is the basis for quantum information processing, with the goal of building superfast quantum computers and transferring information in a completely secure way.

See the referenced research article in Science for a current advance in optical quantum computing; link.)

(The image above is from a research report from a team which has succeeded in creating entanglement of a record number of atoms -- 3,000. Compare that to the hundreds of billions of neurons in the brain, and once again the implausibility of the "walking wave function" idea becomes overwhelming. And note the extreme conditions of low temperature that are required to create this entangled group; the atoms were cooled to 10-millionths of a degree Kelvin, trapped between two mirrors, and subjected to exposure by a single photon (link) And yet presumably decoherence occurs if the temperature raises substantially.)

Here is an interesting lecture on quantum computing by Microsoft scientist Krysta Svore, presented at the Institute for Quantum Computing at the University of Waterloo.

Quantum biology?

I have discussed several times an emerging literature on "quantum consciousness", focusing on Alex Wendt's provocative book Quantum Mind and Social Science: Unifying Physical and Social Ontology. Is it possible in theory for cognitive processes, or neuroanatomical functioning, to be affected by events at the quantum level? Are there known quantum effects within biological systems? Here is one interesting case that is currently being explored by biologists: an explanation of the ability of birds to navigate by the earth's magnetic field in terms of the chemistry of entangled electrons.

Quantum entanglement is defined as a relation between two or more micro-particles (photons, electrons, …) in which the quantum state of one is entangled with the quantum state of the other. When observation of the first part of the pair brings about alteration of the quantum state in that particle, quantum theory entails that the state of the second particle will change as well.

It has been hypothesized that the ability of birds to navigate by reference to the earth’s magnetic field may be explained by quantum effects of electrons in molecules (cryptochromes) in the bird’s retina. Thorsten Ritz is a leader in this area of research. In "Magnetic Compass of Birds Is Based on a Molecule with Optimal Directional Sensitivity" he and his co-authors describes the hypothesis in these terms (link):

The radical-pair model (7,8) assumes that these properties of the avian magnetic compass—light-dependence and insensitivity to polarity—directly reflect characteristics of the primary processes of magnetoreception. It postulates a crucial role for specialized photopigments in the retina. A light-induced electron-transfer reaction creates a spin- correlated radical pair with singlet and triplet states. (3451)

Here is the chemistry from the same article (3452):

Markus Tiersch and Hans Briegel address these findings in "Decoherence in the chemical compass: the role of decoherence for avian magnetoreception". They describe the hypothetical mechanism of paired-electron chemistry as a mechanism in birds for detecting magnetic fields (link):

Certain birds, including the European robin, have the remarkable ability to orient themselves, during migration, with the help of the Earth's magnetic field [3-6]. Responsible for this 'magnetic sense' of the robin, according to one of the main hypotheses, seems to be a molecular process called the radical pair mechanism [7,8] (also, see [9,10] for reviews that include the historical development and the detailed facts leading to the hypothesis). It involves a photo-induced spatial separation of two electrons, whose spins interact with the Earth's magnetic field until they recombine and give rise to chemical products depending on their spin state upon recombination, and thereby to a different neural signal. The spin, as a genuine quantum mechanical degree of freedom, thereby controls in a non-trivial way a chemical reaction that gives rise to a macroscopic signal on the retina of the robin, which in turn influences the behaviour of the bird. When inspected from the viewpoint of decoherence, it is an intriguing interplay of the coherence (and entanglement) of the initial electron state and the environmentally induced decoherence in the radical pair mechanism that plays an essential role for the working of the magnetic compass. (4518)

So the hypothesis is that birds (and possibly other organisms) have evolved ways of exploiting "spin chemistry" to gain a signal from the presence of a magnetic field. What is spin chemistry? Here is a definition from the spin chemistry website (yes, spin chemistry has its own website!) (link):

Broadly defined, Spin Chemistry deals with the effects of electron and nuclear spins in particular, and magnetic interactions in general, on the rates and yields of chemical reactions. It is manifested as spin polarization in EPR and NMR spectra and the magnetic field dependence of chemical processes. Applications include studies of the mechanisms and kinetics of free radical and biradical reactions in solution, the energetics of photosynthetic electron transfer reactions, and various magnetokinetic effects, including possible biological effects of extremely low frequency and radiofrequency electromagnetic fields, the mechanisms by which animals can sense the Earth’s magnetic field for orientation and navigation, and the possibility of manipulating radical lifetimes so as to control the outcome of their reactions. (link)

Tiersch and Briegel go through the quantum-mathematical details on how this process might work in the case of molecules that might be found in birds' retinas. Here is the conclusion drawn by Tiersch and Briegel:

It seems that the radical pair mechanism provides an instructive example of how the behaviour of macroscopic entities, like the European robin, may indeed remain connected, in an intriguing way, to quantum processes on the molecular level. (4538)

This line of thought is still unconfirmed, as both Ritz and Tiersch and Briegel are careful to emphasize. If confirmed, it would provide an affirmative answer to the question posed above -- are there biological effects of quantum-mechanical events? But even if confirmed, it doesn't seem like an enormously surprising result. It traces out a chemical reaction which proceeds differently depending on whether entangled electrons in molecules stimulated by a photon have been influenced by a magnetic field; this gives the biological system a signal about the presence of a magnetic field that does in fact depend on the quantum states of a pair of electrons. Entanglement is now well confirmed, so this line of thought isn't particularly radical. But this is entirely less weird than the idea that quantum particles are "conscious", or that consciousness extends all the way down to the quantum level (quantum interactive dualism, as Henry Stapp calls it; link). And it is nowhere nearly as perplexing as the claim that "making up one's mind" is a form of a collapsing quantum state represented by a part of the brain.

(Of interest on this set of topics is a recent collection, Quantum physics meets the philosophy of mind, edited by Antonella Corradini and Uwe Meixne. Here is a video in which Hans Briegel discusses research on modeling quantum effects on agents: https://phaidra.univie.ac.at/detail_object/o:300666.)

Is the mind/body problem relevant to social science?

Is solving the mind-body problem crucial to providing a satisfactory sociological theory?

No, it isn't, in my opinion. But Alex Wendt thinks otherwise in Quantum Mind and Social Science: Unifying Physical and Social Ontology. In fact, he thinks a solution to the mind-body problem is crucial to a coherent social science. Which is to say, in Wendt's words:

Some of the deepest philosophical controversies in the social sciences are just local manifestations of the mind–body problem. So if the theory of quantum consciousness can solve that problem then it may solve fundamental problems of social science as well. (5)

Why so? There are two core problems in the philosophy of mind that Wendt thinks are unavoidable and must be confronted by the social sciences. The first is the problem of consciousness and intentionality; the second is the problem of freedom of the will. How is it possible for a physical, material system (a computer, a brain, a vacuum cleaner) to possess any of these mental properties?

Experts refer to the "hard problem" in the philosophy of mind. We might also call this the discontinuity problem: the unavoidable necessity of a radical break between a non conscious substrate and a conscious super-strate. How is it possible for an amalgamation of inherently non-conscious things (neurons, transistors, routines in an AI software package) to create an ensemble that possesses consciousness? Isn't this as mysterious as imagining a world in which matter is composed of photons, where the constituents lack mass and the ensemble possesses mass? In such a case we would get mass out of non-mass; in the case of consciousness we get consciousness out of non-consciousness. "Pan-massism" would be a solution: all things, from stars to boulders to tables and chairs to subatomic components, possess mass.

But physicalist philosophers of mind are not persuaded by the discontinuity argument. As we have noted many times in this place, there are abundant examples of properties that are emergent in a non-spooky way. It simply is not the case that the sciences need to proceed in a Cartesian, foundationalist fashion. We do not need to reduce each level of the world to the workings of a lower level of things and processes.

Consider a parallel problem: is solving the question of the fundamental mechanisms of quantum mechanics crucial for understanding chemistry and the material properties of medium-scale objects? Here it seems evident that we can't require this level of ontological continuity from micro to macro -- in fact, there may reasons for believing the task cannot be carried out in principle. (See the earlier post on the question of whether chemistry supervenes upon quantum theory; link.)

Here is the solution to the mind-body problem that Wendt favors: panpsychism. Panpsychism is the notion that consciousness is a characteristic of the world all the way down -- from human beings to sub-atomic particles.

Panpsychism takes a known effect at the macroscopic level–that we are conscious–and scales it downward to the sub-atomic level, meaning that matter is intrinsically minded. (30) 

Exploiting this possibility, quantum consciousness theorists have identified mechanisms in the brain that might allow this sub-atomic proto-consciousness to be amplified to the macroscopic level. (5)

Quantum consciousness theory builds on these intuitions by combining two propositions: (1) the physical claim of quantum brain theory that the brain is capable of sustaining coherent quantum states ( Chapter 5 ), and (2) the metaphysical claim of panpsychism that consciousness inheres in the very structure of matter ( Chapter 6 ). (92)

Panpsychism strikes me as an extravagant and unhelpful theoretical approach, however. Why should we attempt to analyze "Robert is planning to embarrass the prime minister" into a vast ensemble of psychic bits associated with the sub-atomic particles of his body? How does it even make sense to imagine a "sub-atomic bit of consciousness"? And how does the postulation of sub-atomic characteristics of consciousness give us any advantage in understanding ordinary human consciousness, deliberation, and intentionality?

Another supposedly important issue in the domain of the mind-body problem is the problem of freedom of the will. As ordinary human beings in the world we work on the assumption that individuals make intentional choices among feasible alternatives; their behavior is not causally determined by any set of background conditions. But if individuals are composed of physically deterministic parts (classical physics) then how is it possible for the organism to be "free"? And equally, if individuals are composed of physically indeterministic parts (probabilistic sub-particles) then how is it possible for the organism to be intentional (since chance doesn't produce intentionality)? So neither classical physics nor quantum physics seems to leave room for intentional free choice among alternatives.

Consider the route of the Roomba robotic vacuum cleaner through the cluttered living room (link): its course may appear either random or strategic, but in fact it is neither. Instead, the Roomba's algorithms dictate the turns and trajectories that the device takes in either an unobstructed run or an obstructed run. The behavior of the Roomba is determined by its algorithms and the inputs of its sensors; there is no room for freedom of choice in the Roomba. How can it be different for a dog or a human being, given that we too are composed of algorithmic computing systems?

Social theory presupposes intentional actors; but our current theories of neuroscience don't permit us to reproduce how intentionality, consciousness, and freedom are possible. So don't we need to solve the problem of freedom of the will before we can construct valid sociological theories that depend upon conscious, intentional and free actors?

Again, my answer is negative. It is an interesting question, to be sure, how freedom, consciousness, and intentionality can emerge from the wetware of the brain. But it is not necessary to solve this problem before we proceed with social science. Instead, we can begin with phenomenological truisms: we are conscious, we are intentional, and we are (in a variety of conditioned senses) free. How the organism achieves these higher-level capabilities is intriguing to study; but we don't have to premise our sociological theories on any particular answer to this question.

So the position I want to take here is that we don't have to solve the mysteries of quantum mechanics in order to understand social processes and social causation. We can bracket the metaphysics of the quantum world -- much as the Copenhagen interpretation sought to do -- without abandoning the goal of providing a good explanation of aspects of the social world and social actors. Wendt doesn't like this approach:

Notwithstanding its attractions to some, this refusal to deal with ontological issues also underlies the main objection to the Copenhagen approach: that it is essentially incomplete. (75)

But why is incompleteness a problem for the higher-level science (psychology or sociology, for example)? Why are we not better served by a kind of middle-level theory of human action and the social world, a special science, that refrains altogether from the impulse of reductionism? This middle-level approach would certainly leave open the research question of how various capabilities of the conscious, intentional organism are embodied in neurophysiology. But it would not require providing such an account in order to validate the human-level or social-level theory.

Quantum cognition?

Alexander Wendt proposes a radical idea in his Quantum Mind and Social Science: Unifying Physical and Social Ontology: that we should reconsider fundamentals of the social sciences to reflect emerging research on "quantum consciousness" and cognition. He describes his aim in these terms:

In this book I explore the possibility that this [classical physics] foundational assumption of social science is a mistake, by re-reading social science "through the quantum." More specifically, I argue that human beings and therefore social life exhibit quantum coherence -- in effect, that we are walking wave functions. (3)

A keystone to Wendt's argument is what he regards as the credibility and predictive niceness of "quantum decision theory". The foundational text in this field is Busemeyer and Bruza, Quantum Models of Cognition and Decision. Busemeyer and Bruza argue here, and elsewhere, that the mathematics and concepts of quantum mechanics in physics have seemingly relevant application to the field of cognition and judgment as well. For example, the idea of "wave function collapse" appears to have analogy with the resolution of uncertainty onto decision by a human cognitive agent. Busemeyer and Bruza offer six fundamental analogies between quantum mechanics and cognition:

• judgments are based on indefinite states
• judgments create rather than record
• judgments disturb each other, introducing uncertainty
• judgments do not always obey classic logic
• judgments do not obey the principles of unicity
• cognitive phenomena may not be decomposable

For these and related reasons Busemeyer and Bruza argue that the mathematics, logic, and concepts of quantum mechanics may allow us to reach better traction with respect to the processes of belief acquisition and judgment that constitute human cognition. So far so good -- there may be a mathematical homology between quantum states in the micro-physical world and states of knowledge acquisition at the level of acquisition.

However, Busemeyer and Bruza are entirely explicit in saying that they regard this solely as a formal analogy -- not a hypothesis about the real underlying structure of human thought. They explicitly deny that they find evidence to support the idea that consciousness is a quantum phenomenon at the sub-molecular level. They are "agnostic toward the so-called 'quantum mind' hypothesis" (kl 156). Their use of the mathematics of quantum mechanics is formal rather than substantive -- more akin to using the mathematics of fluid dynamics to represent flow through a social network than arriving at a theory of the real constitution of a domain as a basis for explaining its characteristics.

This book is not about quantum physics per se, but instead it explores the application of the probabilistic dynamic system created by quantum theory to a new domain – the field of cognition and decision making. (kl 245)

So the application is heuristic rather than realistic:

We motivate the use of quantum models as innovative abstractions of existing problems. That is all. These abstractions have the character of idealizations in the sense there is no claim as to the validity of the idealization “on the ground.” (kl 171)

Instead [our theory] turns to quantum theory as a fresh conceptual framework for explaining empirical puzzles, as well as a rich new source of alternative formal tools. To convey the idea that researchers in this area are not doing quantum mechanics, various modifiers have been proposed to describe this work, such as quantum-like models of cognition, cognitive models based on quantum structure, or generalized quantum models. (kl 156)

Given the key role this body of research plays in Wendt's arguments about the social sciences, it is worth considering how it has been received in the relevant academic communities. H. Van Dyke Parunak reviews the work in Computing Reviews (link). Parunak emphasizes the point made here, that the book is explicit in declaring that it does not provide support for the idea of "quantum cognition" as a manifestation of underlying quantum physical processes. He observes that "a more accurate title, but much less exciting, would be Hilbert space models of cognition and decision," emphasizing the purely formal and mathematical nature of their arguments. Quantum mechanics provides a computational model for cognition based on quantum probability theory in their work, not an ontology of the cognitive process. Here is a short piece by Trueblood, Pothos, and Busemeyer in Frontiers in Psychology that spells out the mathematical assumptions that are invoked here (link).

What is perhaps less known is that the ingenious physicists who developed quantum mechanics also invented a new theory of probability, since classical probability (CP) theory was inconsistent with their bold new theory of the physical world. QP theory refers to the rules for assigning probabilities to events from quantum mechanics, without the physics. QP theory is potentially applicable to any area where there is a need to compute probabilities. ("Quantum probability theory as a common framework for reasoning and similarity")

Here is a review article that proposes a series of tests of "quantum-like" models of judgment (link). Here is how the authors describe the field of quantum-like models of cognition:

Recently, a research field that rely on so-called “quantum” or “quantum-like” models has developed to account for such behaviors. The qualifier “quantum” is used to indicate that the models exploit the mathematics of a contemporary physical theory, quantum mechanics. Note that only some mathematical tools of quantum mechanics are employed, and that the claim is not that these models are justified by an application of quantum physics to the brain. For that reason, we shall prefer to call them “quantum-like” models. Such models put into question two classical characteristics recalled above: they abandon Bayesian probabilities for others which are similar to probabilities in quantum mechanics, and they allow for preferences or attitudes to be undetermined. Quantum-like models have received much interest from psychologists, physicists, economists, cognitive scientists and philosophers. For example, new theoretical frameworks have been proposed in decision theory and bounded rationality (Danilov and Lambert-Mogiliansky 2008 and 2010, Yukalov and Sornette 2011). (2)

This description too emphasizes the purely formal nature of this theory; it is an attempt to apply some of the mathematical models and constructs of quantum theory to the empirical problems of cognition and judgment. They go beyond this observation, however, by attempting to assess the ability of the mathematics to fit the data. Their overall judgment is dubious about the applicability of these mathematical tools to the available data on specific aspects of belief formation (22). "After performing the test against available data, the result is quite clear: non-degenerate models are not an option, being not empirically adequate or not needed."

This is all relevant to a discussion of Wendt's work, because Wendt's premise is solidly realist: he wants to seriously consider the possibility or likelihood of "quantum consciousness". This is the idea that thought and mental activity are the manifestations of subatomic quantum effects.

Quantum brain theory takes known effects at the sub-atomic level and scales them upward to the macroscopic level of the brain. (31) 

Hence the central question(s) of this book: (a) how might a quantum theoretic approach explain consciousness and by extension intentional phenomena, and thereby unify physical and social ontology, and (b) what are some implications of the result for contemporary debates in social theory? (29)

For the price of the two claims of quantum consciousness theory –that the brain is a quantum computer and that consciousness inheres in matter at the fundamental level –we get solutions to a host of intractable problems that have dogged the social sciences from the beginning. These claims are admittedly speculative, but neither is precluded by what we currently know about the brain or quantum physics, and given the classical materialist failure to make progress on the mind–body problem, at this point they look no more speculative than the orthodoxy –and the potential pay-off is huge. (35)

These are tantalizing ideas. It is clear that they are intended as substantive, not merely formal or mathematical. We are asked to take seriously, as an empirical hypothesis, the idea that the brain is a quantum machine and its gross behavior (memory, belief, judgment) is substantively influenced by that quantum substrate. But it is fundamentally unclear whether the findings of Busemeyer and Bruza or other practitioners of quantum probability in the field of cognition provide any support at all for the substantive quantum-consciousness hypothesis.

Is chemistry supervenient upon physics?

Many philosophers of science and physicists take it for granted that "physics" determines "chemistry". Or in terms of the theory of supervenience, it is commonly supposed that the domain of chemistry supervenes upon the domain of fundamental physics. This is the thesis of physicalism: the idea that all causation ultimately depends on the causal powers of the phenomena described by fundamental physics.

R. F. Hendry takes up this issue in his contribution to Davis Baird, Eric Scerri, and Lee McIntyre's very interesting volume, Philosophy of Chemistry. Hendry takes the position that this relation of supervenience does not obtain; chemistry does not supervene upon fundamental physics.

Hendry points out that the dependence claim depends crucially on two things: what aspects of physics are to be considered? And second, what kind of dependency do we have in mind between higher and lower levels? For the first question, he proposes that we think about fundamental physics -- quantum mechanics and relativity theory (174). For the second question, he enumerates several different kinds of dependency: supervenience, realization, token identity, reducibility, and derivability (175). In discussing the macro-property of transparency in glass, he cites Jaegwon Kim in maintaining that transparency in glass is "nothing more" than the features of the microstructure of glass that permit it to transmit light. But here is a crucial qualification:

But as Kim admits, this last implication only follows if it is accepted that “the microstructure of a system determines its causal/nomic properties” (283), for the functional role is specified causally, and so the realizer’s realizing the functional property that it does (i.e., the realizer–role relation itself) depends on how things in fact go in a particular kind of system. For a microstructure to determine the possession of a functional property, it must completely determine the causal/nomic properties of that system. (175)

Hendry argues that the key issue underlying claims of dependence of B upon A is whether there is downward causation from the level of chemistry (B) to the physical level (A); or, on the contrary, is physics "causally complete". If the causal properties of the higher level are fully fixed by the causal properties of the underlying level, then supervenience is possible; but if the higher level has causal properties that permit influence on the lower level, then supervenience is not possible.

In order to gain insight into the specific issues arising concerning chemistry and physics, Hendry makes use of the "emergentist" thinking associated with C.D. Broad. He finds that Broad offers convincing arguments against "Pure Mechanism", the view that all material things are determined by the micro-physical level (177). Here are Broad's two contrasting possibilities for understanding the relations between higher levels and the physical micro-level:

(i) On the first form of the theory the characteristic behavior of the whole could not, even in theory, be deduced from the most complete knowledge of the behavior of its components, taken separately or in other combinations, and of their proportions and arrangements in this whole . . .
(ii) On the second form of the theory the characteristic behavior of the whole is not only completely determined by the nature and arrangements of its components; in addition to this it is held that the behavior of the whole could, in theory at least, be deduced from a sufficient knowledge of how the components behave in isolation or in other wholes of a simpler kind (1925, 59). [Hendry, 178]

The first formulation describes "emergence", whereas the second is "mechanism". In order to give more contemporary expression to the two views Hendry introduces the key concept of quantum chemistry, the Hamiltonian for a molecule. A Hamiltonian is an operator describing the total energy of a system. A "resultant" Hamiltonian is the operator that results from identifying and summing up all forces within a system; a configurational Hamiltonian is one that has been observationally adjusted to represent the observed energies of the system. The first version is "fundamental", whereas the second version is descriptive.

Now we can pose the question of whether chemistry (behavior of molecules) is fixed by the resultant Hamiltonian for the components of the atoms involved (electrons, protons, neutrons) and the forces that they exert on each other. Or, on the other hand, does quantum chemistry achieve its goals by arriving at configurational Hamiltonians for molecules, and deriving properties from these descriptive operators? Hendry finds that the latter is the case for existing derivations; and this means that quantum chemistry (as it is currently practiced) does not derive chemical properties from fundamental quantum theory. Moreover, the configuration of the Hamiltonians used requires abstractive description of the hypothesized geometry of the molecule and the assumption of the relatively slow motion of the nucleus. But this is information at the level of chemistry, not fundamental physics. And it implies downward causation from the level of chemical structure to the level of fundamental physics.

Furthermore, to the extent that the behavior of any subsystem is affected by the supersystems in which it participates, the emergent behavior of complex systems must be viewed as determining, but not being fully determined by, the behavior of their constituent parts. And that is downward causation. (180)

So chemistry does not derive from fundamental physics. Here is Hendry's conclusion, supporting pluralism and anti-reductionism in the case of chemistry and physics:

On the other hand is the pluralist version, in which physical law does not fully determine the behavior of the kinds of systems studied by the special sciences. On this view, although the very abstractness of the physical theories seems to indicate that they could, in principle, be regarded as applying to special science systems, their applicability is either trivial (and correspondingly uninformative), or if non-trivial, the nature of scientific inquiry is such that there is no particular reason to expect the relevant applications to be accurate in their predictions.... The burden of my argument has been that strict physicalism fails, because it misrepresents the details of physical explanation (187)

Hendry's argument has a lot in common with Herbert Simon's arguments about system complexity (link) and with Nancy Cartwright's arguments about the limitations of (real) physics' capability of representing and calculating the behavior of complex physical systems based on first principles (link). In each case we get a pragmatic argument against reductionism, and a weakened basis for assuming a strict supervenience relation between higher-level structures and a limited set of supposedly fundamental building blocks. What is striking is that Hendry's arguments undercut the reductionist impulse at what looks like its most persuasive juncture -- the relationship between quantum physics and quantum chemistry.

Quantum mental processes?

One of the pleasant aspects of a long career in philosophy is the occasional experience of a genuinely novel approach to familiar problems. Sometimes one's reaction is skeptical at first -- "that's a crazy idea!". And sometimes the approach turns out to have genuine promise. I've had that experience of moving from profound doubt to appreciation several times over the years, and it is an uplifting learning experience. (Most recently, I've made that progression with respect to some of the ideas of assemblage and actor-network theory advanced by thinkers such as Bruno Latour; link, link.)

I'm having that experience of unexpected dissonance as I begin to read Alexander Wendt's Quantum Mind and Social Science: Unifying Physical and Social Ontology. Wendt's book addresses many of the issues with which philosophers of social science have grappled for decades. But Wendt suggests a fundamental switch in the way that we think of the relation between the human sciences and the natural world. He suggests that an emerging paradigm of research on consciousness, advanced by Giuseppi Vitiello, John Eccles, Roger Penrose, Henry Stapp, and others, may have important implications for our understanding of the social world as well. This is the field of "quantum neuropsychology" -- the body of theory that maintains that puzzles surrounding the mind-body problem may be resolved by examining the workings of quantum behavior in the central nervous system. I'm not sure which category to put the idea of quantum consciousness yet, but it's interesting enough to pursue further.

The familiar problem in this case is the relation between the mental and the physical. Like all physicalists, I work on the assumption that mental phenomena are embodied in the physical infrastructure of the central nervous system, and that the central nervous system works according to familiar principles of electrochemistry. Thought and consciousness are somehow the "emergent" result of the workings of the complex physical structure of the brain (in a safe and bounded sense of emergence). The novel approach is the idea that somehow quantum physics may play a strikingly different role in this topic than ever had been imagined. Theorists in the field of quantum consciousness speculate that perhaps the peculiar characteristics of quantum events at the sub-atomic level (e.g. quantum randomness, complementary, entanglement) are close enough to the action of neural networks that they serve to give a neural structure radically different properties from those expected by a classical-physics view of the brain. (This idea isn't precisely new; when I was an undergraduate in the 1960s it was sometimes speculated that freedom of the will was possible because of the indeterminacy created by quantum physics. But this wasn't a very compelling idea.)

Wendt's further contribution is to immerse himself in some of this work, and then to formulate the question of how these perspectives on intentionality and mentality might affect key topics in the philosophy of society. For example, how do the longstanding concepts of structure and agency look when we begin with a quantum perspective on mental activity?

A good place to start in preparing to read Wendt's book is Harald Atmanspacher's excellent article in the Stanford Encyclopedia of Philosophy (link). Atmanspacher organizes his treatment into three large areas of application of quantum physics to the problem of consciousness: metaphorical applications of the concepts of quantum physics; applications of the current state of knowledge in quantum physics; and applications of possible future advances in knowledge in quantum physics.

Among these [status quo] approaches, the one with the longest history was initiated by von Neumann in the 1930s.... It can be roughly characterized as the proposal to consider intentional conscious acts as intrinsically correlated with physical state reductions. (13)

A physical state reduction is the event that occurs when a quantum probability field resolves into a discrete particle or event upon having been measured. Some theorists (e.g. Henry Stapp) speculate that conscious human intention may influence the physical state reduction -- thus a "mental" event causes a "physical" event. And some process along these lines is applied to the "activation" of a neuronal assembly:

The activation of a neuronal assembly is necessary to make the encoded content consciously accessible. This activation is considered to be initiated by external stimuli. Unless the assembly is activated, its content remains unconscious, unaccessed memory. (20)

Also of interest in Atmanspacher's account is the idea of emergence: are mental phenomena emergent from physical phenomena, and in what sense? Atmanspacher specifies a clear but strong definition of emergence, and considers whether mental phenomena are emergent in this sense:

Mental states and/or properties can be considered as emergent if the material brain is not necessary or not sufficient to explore and understand them. (6)

This is a strong conception in a very specific way; it specifies that material facts are not sufficient to explain "emergent" mental properties. This implies that we need to know some additional facts beyond facts about the material brain in order to explain mental states; and it is natural to ask what the nature of those additional facts might be.

The reason this collection of ideas is initially shocking to me is the difference in scale between the sub-atomic level and macro-scale entities and events. There is something spooky about postulating causal links across that range of scales. It would be wholly crazy to speculate that we need to invoke the mathematics and theories of quantum physics to explain billiards. It is pretty well agreed by physicists that quantum mechanics reduces to Newtonian physics at this scale. Even though the component pieces of a billiard ball are quantum entities with peculiar properties, as an ensemble of 10^25 of these particles the behavior of the ball is safely classical. The peculiarities of the quantum level wash out for systems with multiple Avogadro's numbers of particles through the reliable workings of statistical mechanics. And the intuitions of most people comfortable with physics would lead them to assume that neurons are subject to the same independence; the scale of activity of a neuron (both spatial and temporal) is orders of magnitude too large to reflect quantum effects. (Sorry, Schrodinger's cat!)

Charles Seife reports a set of fundamental physical computations conducted by Max Tegmark intended to demonstrate this in a recent article in Science Magazine, "Cold Numbers Unmake the Quantum Mind" (link). Tegmark's analysis focuses on the speculations offered by Penrose and others on the possible quantum behavior of "microtubules." Tegmark purports to demonstrate that the time and space scales of quantum effects are too short by orders of magnitude to account for the neural mechanisms that can be observed (link). Here is Tegmark's abstract:

Based on a calculation of neural decoherence rates, we argue that the degrees of freedom of the human brain that relate to cognitive processes should be thought of as a classical rather than quantum system, i.e., that there is nothing fundamentally wrong with the current classical approach to neural network simulations. We find that the decoherence time scales (∼10^−13–10^−20s) are typically much shorter than the relevant dynamical time scales (∼10^−3–10^−1s), both for regular neuron firing and for kinklike polarization excitations in microtubules. This conclusion disagrees with suggestions by Penrose and others that the brain acts as a quantum computer, and that quantum coherence is related to consciousness in a fundamental way. (link)

I am grateful to Atmanspacher for providing such a clear and logical presentation of some of the main ideas of quantum consciousness; but I continue to find myself sceptical. There is a risk in this field to succumb to the temptation towards unbounded speculation: "Maybe if X's could influence Y's, then we could explain Z" without any knowledge of how X, Y, and Z are related through causal pathways. And the field seems sometimes to be prey to this impulse: "If quantum events were partially mental, then perhaps mental events could influence quantum states (and from there influence macro-scale effects)."

In an upcoming post I'll look closely at what Alex Wendt makes of this body of theory in application to the level of social behavior and structure.