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LATEST DIALOGUES Does Brain Imaging Corroborate or Contradict Materialism?

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Straw-man picture by Clyde Robinson. Reproduced under CC BY 2.0.

The two essays I wrote prior to this one have commanded a lot of interest and attention (see here and here). They discuss recent brain imaging studies on the effects of psychedelics. Surprisingly, the results have shown that, unlike what one would ordinarily expect from a materialist perspective, the increase in the richness and intensity of experience following the intake of psychedelics correlates with reductions of brain activity. Although these results, in and of themselves, do not single-handedly refute materialism, they do contradict its intuitions. After all, under materialism, brain activity constitutes experience. Therefore, I’ve referred to these studies as circumstantial evidence for the alternative, non-materialist philosophy I argue for (analytic summary freely available here).

Since publishing those two essays, I have been confronted with a barrage of straw-man arguments against my philosophy. Straw-man arguments are those wherein a critic first misconstrues my views (creating the “straw-man”) and then proceeds to dismantle his misrepresentation of what I am saying (destroying the straw-man). With this essay, I hope to clarify a few key aspects of my position, in the hope that my critics will better understand what I am trying to get across. Nothing is discussed below that hasn’t already been covered before, in one way or another, in the body of my work. But since the subject has now gained renewed relevance, it is worthwhile to reformulate certain clarifications.

Straw-man 1: Materialism does not imply that more experience should correlate with more overall brain activity.

And neither do I claim that it does. To clarify this, let us try to specify precisely what materialism does entail. In what follows, I choose my words carefully and precisely. In the interest of avoiding misinterpretations and further straw-men, I ask that you pay careful attention to my specific choice of words. Here we go:

According to materialism, certain aspects or patterns of brain activity constitute subjective experience. These particular aspects or patterns of brain activity are called the ‘neural correlates of consciousness’, or ‘NCCs’ for short. Notice that I use the word ‘activity’ here in the broad sense of metabolism itself (as such, “activity” is not restricted to e.g. neural firings alone). This way, only a dead, non-metabolizing brain has no activity. The activity of the brain thus consists of both NCCs and other neural processes that aren’t NCCs. The latter are supposedly unconscious processes. Although these unconscious processes are still activity, their reduction doesn’t necessarily correlate with a reduction of conscious experience, for they aren’t NCCs. In fact, if these allegedly unconscious processes are inhibitory, their reduction may even cause an increase in NCCs and, therefore, conscious experience. All of this is what materialism entails.

Now, clearly an increase in NCCs may be accompanied by an even greater decrease in unconscious processes, leading to an overall decrease in brain activity. So indeed, materialism does not necessarily imply that more experience should always correlate with more overall brain activity. What’s my point then?

It is this: under materialism, an increase in the richness/intensity of experience must still be accompanied by an increase in the metabolism associated with the NCCs, for subjective experiences are supposedly constituted by the NCCs. This is inescapable. After all, richer/intenser experience spans a broader information space in consciousness, and only increased metabolism can create that broader information space in the physical substrate of the brain. Any other alternative would decouple subjective experience from the workings of the living brain information-wise, which would directly contradict materialism. As such, materialism does imply a form of proportionality, but a local one: the richness/intensity of experience must be proportional to the compound metabolic level of the NCCs, for experience allegedly is the NCCs.

Having clarified this, what is the significance I see in the fact that psychedelic trances are not accompanied by increases in activity anywhere in the brain, but only reductions (see e.g. this study)? As we’ve just seen, materialism implies that a significant increase in the richness/intensity of experience should be accompanied by a significant increase in the compound metabolic level of the NCCs. We also know that psychedelic trances significantly increase the richness/intensity of experience when compared to placebo (more on this in point 3 below). As such, one should have observed at least localized but significant increases in brain activity in those areas of the brain corresponding to NCCs, even if the activity elsewhere (corresponding to unconscious processes) decreased even more, leading to less total brain activity. That these local increases were not observed makes any potential materialist explanation of the psychedelic experience at least counterintuitive. Allow me to elaborate.

It is, in principle, conceivable that the spatial resolution of functional brain scanners is such that, in the studies mentioned above, researchers couldn’t discern between, on the one hand, hypothetical NCCs whose activity could have increased and, on the other hand, unconscious processes right ‘on top of them’ whose metabolism decreased even more, thereby masking the increase in the NCCs. But this stretches credulity and plausibility. It would require the rather astonishing coincidence that each and every part of each and every relevant NCC consistently had an unconscious process right ‘on top of it,’ intermingled with it, whose metabolism happened to decrease so significantly as to mask the corresponding NCC increase. There is no reason why this should be so. Different neural processes are often easily discernible from each other in brain imaging, otherwise brain imaging wouldn’t be of much use.

To put all this in perspective, consider this other brain imaging study. It shows that, if you dream that you are clenching your hand, the brain areas associated with hand motion light up clearly in an fMRI. Now think about it: dreams and psychedelic trances are analogous in that neither can be attributed to sensory inputs. Both experiences are imagined. Yet, in a dream, when you experience something as dull as clenching your dreamed-up hand, the corresponding brain activations can be clearly discerned. But when you undergo mind-boggling psychedelic excursions into other mental universes, scientists can discern no conclusive activations anywhere in the brain. You be the judge of whether this tell us something about the likelihood of materialism being correct. Personally, I think it does.

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Straw-man 2: Under materialism, several different types of neural dynamics are plausible candidates for constituting experience, not only neural firings.

I do not dispute this either. My point is much more generic and applies to whatever the NCCs might turn out to be, as explained in this passage of my book Why Materialism Is Baloney:

By postulating that subjective experiences are neural processes [i.e. the NCCs], the reigning materialist paradigm tentatively explains the ordinary correlations between mind states and brain states rather simply. Yet, this paradigm is currently articulated in only a vague and promissory manner, in that neuroscience does not specify precisely or unambiguously what measurable parameters of neural processes map onto what qualities of subjective experience.

This is an important point, so let me belabor this a bit. If every conscious experience is nothing but a neural process [i.e. an NCC], then there are two points-of-view from which to observe the same information flow associated with any experience: the perspective from the inside – that is, the experience itself – and the perspective from the outside – that is, what a neuroscientist sees when measuring the activity of a person’s brain while the person is having the experience. If materialism is correct, there always has to be a strict one-to-one correspondence between parameters measured from the outside [i.e. the NCCs] and the qualities of what is experienced form the inside. After all, subjective experience supposedly is what is measured from the outside. For instance, if I see the color red, there have to be measurable parameters of the corresponding neural process in my brain that are always associated with the color red. After all, my experience of seeing red supposedly is the neural process. Similarly, if I feel sad, there have to be measurable parameters of the corresponding neural process in my brain that are always associated with the feeling of sadness. After all, my experience of being sad supposedly is the neural process. You get the picture.

As I mentioned above, neuroscience today is very far from being able to provide a consistent one-to-one mapping between the qualities of a subjective experience and measurable parameters of the corresponding neural process. It is possible to argue that this merely reflects our currently limited progress in finding this mapping and that it will be found in the future as more research is done and new techniques are developed for measuring the finer parameters of brain activity. As a vague and promissory argument, this is unfalsifiable.

So far so good. The problem, however, is this:

Today we find ourselves in a peculiar situation wherein, of all things, ignorance is often used to defend materialism: since nobody can specify unambiguously what physiological process supposedly is consciousness, neuroscientists can always postulate a different hypothetical mapping that conceivably explains any particular experience. All that is required is some – any – level of activity anywhere in the brain, which is not too difficult to find or reasonably assume. The problem, of course, is that one cannot postulate a different materialist theory of consciousness for each different situation and still claim that the evidence supports materialism.

The reason such surprising ambiguity is tolerated was already hinted at in Chapter 1: when it comes to consciousness, there is no way – not even in principle – to logically deduce the properties of subjective experience from the properties of matter. In other words, there is no way to logically deduce conscious perception, cognition, or feeling from the mass, momentum, spin, position, or charge of the subatomic particles making up the brain. Such complete lack of intuition makes it impossible to judge whether a particular mapping between a brain process and a conscious experience is at all reasonable. Therefore, any proposed mapping looks, at first, just as good (or as bad) as any other, a fact easily misused in support of materialism. In an astonishing acknowledgment of how arbitrary the materialist explanations of consciousness can be, militant skeptic Michael Shermer, of all people, admitted that ‘the neuroscience surrounding consciousness’ is ‘nonfalsifiable.’

In all fairness, many neuroscientists readily admit that our current understanding of the brain is very limited. As such, it is entirely legitimate that they remain open to many different alternatives for explaining conscious experience on the basis of material processes. But one cannot make this admission and then turn around and proclaim that neuroscience’s progress has been corroborating materialism.

Straw-man 3: It is not clear that psychedelic trances entail a higher quantity of experience.

I am talking about the felt richness and intensity of experience here, not abstract bean counting. To deny that every person has a clear, living sense of the richness and intensity of their experience is disingenuous. Can we all agree that making love is a richer and intenser experience, which spans a much larger information space in consciousness, than staring at a white wall? Can we all agree that attending a rock concert while suffering from severe indigestion (yes, I’ve been there) is a richer and intenser experience than wiping the floor? More specifically, can we all agree that tripping to the center of the galaxy, reliving your own birth, facing your inner demons, losing your sense of personal identity, and then having God explain the secrets of life, the universe and everything to you (all of which are often reported during psychedelic trances) is a richer and intenser experience than staring at the inner coil of an fMRI scanner? If so, how does materialism then explain the reality of these differences in experiential richness and intensity? That’s the question, not abstract bean counting. Refusing to acknowledge the validity of this question amounts to a denial of reality.

In a psychedelic study at Johns Hopkins, researchers found that 94% of the subjects described a psychedelic experience as among the top five most, or as the topmost, spiritually significant experience of his or her life. To get a taste for how people describe their trances, have a look at a few reports at Erowid’s experience vault. Psychedelic trances are well-known to entail the apotheosis of experience in all its qualities and nuances: visual, auditory, tactile, cognitive, emotional, spiritual, syntactical, logical, etc. While pointing this out during the past couple of days, I have been confronted by a neuroscientist who argued that the fact that an experience is “among the top 5 most important things in your life has NOTHING to do with supposed increases in the quantity of subjective experience.” Astonishingly, the suggestion here seems to be that materialism doesn’t need to explain the most significant experience of one’s life in terms of shifts in brain metabolism. What does, then? Do materialists even need a living brain to claim to explain experience?

This same neuroscientist argued that I am “confusing [the] significance, beauty and emotional impact of these experiences with something far more difficult to measure which is the quantity of moments of experience per unit of time.” But wait a moment: what are “significance,” “beauty” and “emotional impact” if not experiences that themselves need to be explained under a materialist framework? What else could they possibly be? Moreover, who the hell cares about the “quantity of moments of experience per unit of time”? This is one of those ontology-bound flights of abstraction that try to replace reality with a conceptual framework. I don’t experience discrete and countable jelly beans of qualities. I simply experience. I am interested in significance, beauty and emotion, not the “quantity of moments of experience per unit of time,” because it is significance, beauty and emotion that constitute my reality. An ontology that rejects this reality, instead of making sense of it, is a meaningless and useless ontology.

For a dialogue about the mind-body problem to be productive, one has to at least acknowledge the basic facts of human experience, without begging the question of ontology.

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Bernardo Kastrup has a Ph.D. in computer engineering with specializations in artificial intelligence and reconfigurable computing. He has worked as a scientist in some of the world's foremost research laboratories, including the European Organization for Nuclear Research (CERN) and the Philips Research Laboratories (where the "Casimir Effect" of Quantum Field Theory was discovered). Bernardo has authored many academic papers and books on philosophy and science. His most recent book is "The Idea of the World: A multi-disciplinary argument for the mental nature of reality," based on rigorous analytic argument and empirical evidence. For more information, freely downloadable papers, videos, etc., please visit www.bernardokastrup.com.
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