Novella's reply, part 3
(The positions I defend below have been much more extensively, precisely and clearly argued in some of my academic papers.)
|Neuroscientists evaluating fMRI images. Image source: Wikipedia.|
Continuing on with the discussion, Steven Novella's latest response can be found here. In the interest of brevity, in what follows I will focus on the key points of contention, leaving out the parts where I guess we simply agree to disagree, and the less significant parts where we may actually be close to an agreement of sorts. My focus on the points of contention should not be interpreted as a sign that I don't want to acknowledge convergence anywhere; I just think that debating contentious points is much more productive, useful, and interesting.
Prior PET studies did show increases in brain activity with psilocybin.Which was tentatively, yet cogently, explained in the Carhart-Harris study in question: "It is therefore possible that phasic or short-term effects of psilocybin show some rebound that is detected by longer-term changes in glucose metabolism." In other words, what the PET studies showed was not the effect of psilocybin, but a later rebound in metabolism. One should keep in mind that, unlike in the PET study Novella is referring to, in the Carhart-Harris study patients were in the scanner while the drug was being administered, which leaves little room for doubt on the timeline.
These experiences are only “intense” because they are so unreal. This does not require increased neuronal firing.The fallacy here is that Novella talks merely of 'intensity,' while conveniently ignoring the other hallmarks of psychedelic experiences: Their structure, coherence, unfathomable complexity, and the fact that they are often described as "more real than real." (see Rick Strassman's study at the University of New Mexico's School of Medicine, described in his book The Spirit Molecule). Novella is creating a straw-man by subtly, yet massively, under-characterizing the experience, and then casually explaining such under-characterization away. By implying that it's all about mere 'intensity,' he makes it all sound so innocent, while in reality the phenomenology he is taking upon himself to explain embodies the very peak of human conscious experience. Psychedelic trances, alongside mystical experiences, are well-known to entail the apotheosis of subjective experience in all its qualities and nuances: visual, auditory, tactile, cognitive, emotional, syntactical, logical, etc. Such peak experiences are what Novella has to explain without availing himself of extra neuronal firings; not merely an 'intense' experience. So let's make sure that we understand what we are talking about here, and not fall for this little semantic ploy.
In a study at Johns Hopkins (the actual paper is better than this link, but behind a paywall), researchers found that 71% of the volunteers described a psilocybin experience as the top, or among the top five, most spiritually significant of their lives. To get a taste for how volunteers describe psilocybin trances, have a look at a few reports at Erowid's experience vault. The video below may also help: Even though the substance used was DMT, the latter is very similar to psilocybin both chemically and phenomenologically.
But wait; that's not all. We know that the mere clenching of a hand in a regular dream increases neuronal firings in a way that is clearly visible with an fMRI, the same instrument used in the psilocybin study. So I ask you: How come extra neuronal firings are needed to produce the dull dreamed-up experience of clenching a hand, while they are not needed to produce the supposedly dreamed-up, peak experience of going to 'other universes,' interacting with 'entities,' transcending time and space, gaining deep understanding of 'hyper-dimensional' geometry, cognition, and universal history and telos?
Novella's position here simply doesn't add up; it's contradictory and defies reason. Where is Novella's renowned common-sense and skepticism when it comes to his own speculations?
Kastrup argues that if the above explanation were true, then we would expect one of three things: First, we may see increased activity in the disinhibited areas of the brain. This is not necessarily the case, however. The activity might be the same, but since it is no longer being modulated and modified by reality testing centers the net experience can be very different.Here Novella is rejecting the first of the three scenarios I offered him. So far so good, since I believe all three scenarios are untenable. By rejecting the first he is still on the same page with me. Next, he makes a little intermezzo to talk about another topic:
Also – to clarify a point I made in my previous reply to Kastrup – I was not arguing that proportionality never exists when looking at brain function. My point was that proportionality does not necessarily exist in every case, and so the absense of proportionality does not break materialist correlation. There certainly is increased brain activity correlating with increased subjective mental activity, but this simple magnitude correlation does not hold when we are talking about the interaction among the various brain regions.Though the comment above is a little vague and evasive, I construe from it that Novella actually thinks proportionality holds in principle, but is not easily measurable because of other dynamics taking place concurrently and which conflate in the final fMRI pictures. This was my original position, so he may actually be agreeing with me here. Let me unpack my thinking a bit more to see if we are indeed in agreement: As Novella explained, the materialist paradigm entails that consciousness is a physiological process in the brain. Therefore, materialists need to determine what specific physiological process is conscious experience (let's label it the 'consciousness process'). Once that is pinned down, proportionality, of course, must apply fully: If consciousness is the physiological process in question, all qualities of subjective experience must map onto measurable properties of the consciousness process; because they are the same thing. Of course, myriad other processes that also have a metabolic fingerprint may interfere and become intertwined with the 'consciousness process' through e.g. inhibition, which is why Novella denies (the ability to measure) proportionality at a more global and conflated level. If my interpretation here is correct, I'm absolutely fine with this.
Now, based on earlier comments of his, Novella seems to assume that the consciousness process is linked to, and dependent upon, neuronal firings. Indeed, when he earlier argued that psychedelic trances did not require "increased neuronal firings," he was implicitly linking subjective experience to neuronal firings. This way, Novella's position can be stated as following: There can be no conscious experience without associated neuronal firings (although that doesn't mean that neuronal firings are sufficient for consciousness, which is clearly not the case). For a neuron to fire, excitatory synaptic potentials must carry its action potential beyond the firing threshold; i.e. there can be no firings without excitatory processes. Therefore, I construe from all this that Novella in fact agrees with the following statement of my previous post: "...subjective experience is proportional to the intensity of the corresponding excitatory processes (for a given, constant level of inhibition, so the inhibition variable can be isolated)."
Now, if this is indeed true, I am yet more baffled that Novella believes that psychedelic 'trips' do not require, under materialism, extra neuronal firings when compared to the baseline activity. After all: (a) neuronal firings are metabolic gas-guzzlers that do show up clearly in an fMRI; and (b), as discussed above, psychedelic experiences must be associated with the neuronal firings of their corresponding excitatory processes. So where are these processes? Here Novella attempts the explanation under the second one of my three scenarios:
...it is not unreasonable that, in essence, fantasies are going on in the background all the time. Our brains are pattern recognition machines, and there is a vibrant internal conversation going on within our brains all the time.It sounds so reasonable at first sight, doesn't it? But make no mistake: What Novella is suggesting here is that the excitatory processes that supposedly correspond to the full-force of a peak psychedelic experience are playing out all the time in our brains. You may need some time to grok the full implication of this: What other people describe as the top experience of their lives, something they can hardly put in words and which changes their perspective on reality for life, is supposedly happening within your brain right now, as you read this; you just don't notice it. What for? Why? What evolutionary advantage could this have? Subconscious noise I can understand, but coherent, complex, unfathomable storylines playing out unconsciously and wasting metabolic energy all the time, for no reason? Well-constructed, consistent, otherworldly stories that the brain goes through the trouble of building and 'telling' even though there's 'nobody listening'? Well, I'll let you be the judge of that. But mind you this: There is no positive, objective evidence that Novella's promissory speculation here holds any water, so the only criterion of judgment is your reason and common-sense.
Now Novella moves on to address my third scenario: That, by some mysterious hypothetical mechanism, the inhibitions caused by the drug somehow lead subconscious 'noise' to coalesce in the form of a structured, complex, coherent peak experience, and yet without altering the metabolic signature of the original 'noise.' So the two key points that need to be tackled under this third scenario are: (a) What is this hypothetical mechanism that turns neuronal noise into coherent, peak (don't forget this; we're talking peak experiences here) narratives for no reason? And (b) How can such unfathomable phenomenological shift in experience be accomplished without any measurable change in the corresponding metabolic signature given that, according to Novella, experience is metabolism? He then writes:
I think Kastrup vastly underestimates the subconscious “noise” that is going on in the brain during normal activity. There is a large amount of both psychological and neuroscientific evidence for the conclusion that there is a great deal of subconscious processing, including generating lots of noise. We attend demonstrably to a very small portion of this activity. Our brains select small portions of both sensory input and our internal communication to weave into a highly constructed narrative we experience as our stream of consciousness. Altering this stream significantly without changing overall brain activity makes perfect sense.This is the full explanation he gives; His next paragraph is just more of the usual (and entertaining, I might add) mud-throwing aimed at me; So everything he has to say about the third scenario is in the quote above. Pause for a moment... Take a look at the quote again...
...Did you notice it?
He doesn't even attempt to tackle either of the two key points. He only states what I had already not only acknowledged but volunteered myself: That there is subconscious noise; well, "a great deal" of it. Duh. He simply repeats the framing of the scenario and ends with the unsubstantiated pronouncement that it all "makes perfect sense." This may be satisfactory to Novella, but certainly not to me.
So, in summary, Novella argues that my own second and third scenarios could actually be the explanation for the Carhart-Harris psilocybin results. But in doing so, he fails to address the reasons why I had rejected all three scenarios to begin with. Perhaps he's explained it all to his own satisfaction, but in that case I take the liberty to be a little more critical and skeptical. Either way, his explanations are merely tentative and promissory speculation, but that's okay. The real problem is that Novella creates, under both scenarios, a straw-man for the phenomenology he took upon himself to explain: Psychedelic trances are not merely intense experiences; they are the peak experiences in the world of human consciousness. By suggesting that such apotheosis of subjectivity can happen without a measurable delta in neuronal firings w.r.t. an ordinary baseline, Novella is actually flirting with shooting at materialism: If neuronal firings are not necessary to explain peak experiences, what are they necessary for as far as providing ontological grounding for consciousness? Without realizing it, Novella is, in a way, making my own point.