Novella's reply, part 2
|Chimpanzee brain in a jar. Image source: Wikipedia.|
"What I do expect is that they will interpret my posts fairly and not criticize me for not exploring issues that I have explored elsewhere."
This comment, on itself, is fair enough; but in view of what Novella himself did, it becomes ludicrous. Novella wrote in his previous post: "Kastrup seems to be completely unaware of the critical concept of disinhibition and therefore completely misinterprets the significance of the neuroscience research." Now, I had written three entire, detailed articles exploring specifically this issue of disinhibition, all of which I explicitly linked in my original post. So I also "do expect ... that [Novella] will interpret my posts fairly and not criticize me for not exploring issues that I have explored elsewhere."
"In his criiticism [sic] he accused me as assuming causation from correlation, but I never did ... In his new reply he does not acknowledge his error, or point out where I was wrong, or even give any indication that he understands his error."
To the extent that the specific post I was commenting on did put a lot of weight on correlation as evidence for causation, I hesitate on retreating on this point. But if that helps advance the debate towards issues of more substance, fine: Novella's position regarding the relationship between correlation and causation seems to be more nuanced and subtle than I gathered from the specific article I was commenting on.
"The problem, from a scientific point of view, is that the notion that the brain modulates consciousness becomes operationally inseparable from the notion that the brain causes consciousness, at least in terms of the experimental relationship between brain function and mental function."
This is clearly untrue. The modulation hypothesis predicts that there are subjective mind states that do not correlate with objective brain states. Such prediction is invalid under the causation hypothesis. To make this more explicit: Modulation does not establish a fundamental ontological dependency of consciousness on the brain. Here is an analogy: A radio transmitter modulates a carrier-wave according to an audio signal, but the existence of the carrier wave is not dependent on the modulation process; it can exist even when not modulated. Therefore, under the modulation hypothesis of the mind-brain problem, one can in principle find special circumstances under which consciousness departs from the constraints of the modulation: Like the carrier wave, consciousness exists whether it's being modulated or not. But if one claims that consciousness exists only insofar as the brain generates it, then a single instance of a conscious state uncorrelated to a brain state would disprove the claim. So here we have the falsifiability test between these two hypotheses: If it can be experimentally determined that there are mind states uncorrelated with brain states, the causation hypothesis is invalidated and the modulation hypothesis becomes the more likely scenario for explaining the ordinary correlations between brain states and mind states.
"There doesn’t seem to be anything coming from outside the brain – but worse, the concept is completely unnecessary. It is sliced away cleanly by Occam’s razor."
This is acceptable only if one ignores the wealth of evidence for the existence of mind states uncorrelated to brain states. Novella seems to dismiss all evidence related to, for instance, Near-Death Experiences (NDEs), despite much of it being collected under scientific protocols, as in the work of Dr. Pim van Lommel; or that of Dr. Peter Fenwick; or of Dr. Bruce Greyson; and of so many others, like Dr. Sam Parnia, Dr. Raymond Moody, etc.. Perhaps a much-talked about paper titled "There is Nothing Paranormal About Near-Death Experiences" explains away NDEs, despite astonishing admissions of the paper's co-author after publication. Perhaps Harvard neuroscientist Dr. Eben Alexander – who, unlike Novella, has had a first-hand experience with NDEs and, therefore, has more data to work with than Novella – is not competent enough to find an appropriate materialist model for such data.
No, I don't want to go into a debate about NDEs, because I think the evidence extends much beyond NDEs, as I sought to illustrate here (a reference which I hereby incorporate as integral part of this response). A recent new tome is also rich in evidence for mind states uncorrelated to brain states. But independent of the validity of any of these references, my point is this: Though Novella is entitled to hold any opinion he wishes regarding the evidence available for uncorrelated mind states, the evidence is substantial enough (in the form e.g. of myriad peer-reviewed scientific publications, like van Lommel's article in The Lancet, to mention only one example) that reference to it in any debate about the mind-body problem is legitimate; it's a legitimate point of contention. To claim otherwise is to dismiss the validity of the peer-review process, which, for obvious consistency reasons, would force Novella to equally dismiss the other scientific results he uses to justify his positions. So I do not grant Novella's claim above, which I consider arbitrary and incorrect.
"...the introduction of something as extraordinary as mental function apart from the brain is completely unwarranted."
The characterization of non-physical consciousness as "extraordinary" is a paradigm-laden, subjective, and arbitrary one. Thomas Kuhn has already cogently warned us about the dangers of this kind of biased, restrictive thinking.
"He is citing controversial (at best) claims as support for his position. What he calls strong scientific evidence is laughable, is not generally accepted by the scientific community and only persists on the fringe."
This is ludicrous. I just referenced a paper above published in The Lancet. The psilocybin study I mentioned, and which Novella proceeds to comment on immediately after the quote above, was published in the Proceedings of the National Academy of Sciences (PNAS) of the USA. Is PNAS fringe? Is the peer-review process of The Lancet laughable? Controversial, yes; that's how science moves forward, which anyone marginally versed in history will be able to attest to.
Now Novella proceeds to criticize my characterization of brain processes as inhibitory and excitatory:
"He [i.e. me] is confusing different levels of brain activity – this [i.e. excitatory and inhibitory processes] is an accurate description of the effects of specific neurotransmitters on specific receptors on neurons, they will either increase or decrease the activity of those neurons. But this is not a good description of how different parts of the brain interact ... different parts of the brain are active in processing information from other parts of the brain. They modify how the other parts of the brain are working, or the net effect of that processing on our thoughts, feelings, behaviors, and net subjective experience."
So far, okay. But now he attempts to explain how subjects in which brain activity has been reduced through the use of a drug (psilocybin), and not increased anywhere in the brain, can experience unfathomable psychedelic trances:
"When you remove one element from the committee of voices contributing to net experience, that experience changes. It may be that some some other “voices” are more prominent, because they are not being modified, inhibited, or drowned out by other parts of the brain."
This is generic, vague, and explains precisely nothing regarding the psilocybin results. It's curious to note, too, that what Novella calls "voices" are basically excitatory brain processes. That, ironically, brings us right back to my original framing of the problem, which Novella attempted to dismiss only a couple of lines earlier. Be that as it may, let me attempt to sharpen up the discussion and make the issues more explicit: For Novella's point to hold, he has to ground the psychedelic experience on a metabolic process somewhere in the brain; i.e. some brain excitation somewhere. After all, a completely non-excited brain is akin to a dead brain, which cannot produce subjective experience. Now, as I discussed in another article, which Novella is still ignoring despite my repeated references to it, I can then see three scenarios:
- New excitatory processes, not originally present in the placebo baseline, arise and grow due to reduced inhibition;
- Reduced inhibition causes ordinarily subconscious but coherent excitatory processes, already in the placebo baseline, to cross the threshold of awareness without any increase in their metabolic signature;
- When the drug de-activates certain (inhibitory) control centres in the brain, incoherent subconscious noise coalesces, by some unknown mechanism, in the form of a coherent psychedelic 'trip,' and yet with no change in its metabolic signature.
In my previous article (which I hereby incorporate as an integral part of this response), I argued why none of these three scenarios is a reasonable explanation for the observations of the psilocybin study. I submit that argument here, by reference, to Dr. Novella. If Novella prefers other scenarios, that's fine too; so long as we can move the discussion forward on explicit, sharp, and specific terms – not vague hand-waving or obscurantism.
"He gives as an example the intense mystical experiences caused by some drugs or during out of body experiences. The latter is now known to be caused by inhibiting brain regions, not enhancing them."
That's precisely my point. Thank you.
"Further, this is preliminary research and neuroscientists are still debating how to interpret it, so it is hardly a solid premise with which to discard the materialist paradigm."
This seems to be Novella's first sort-of-admission that the results in this paper are indeed problematic for materialists. But this aside, I explicitly acknowledged before that Carhart-Harris' and Nutt's paper is but one study, and that science is made from patterns of results, not individual results. Here I said literally: "I think that, although this research represents a milestone in our understanding of the relationship between mind and brain, it is just one study. Its results must be replicated before definite conclusions can be arrived at." However, I went on to say: "Yet, there is a broader pattern associating peak subjective experiences with reduced blood flow to the brain, as I wrote in another article." I stand by this. Moreover, let's not lose from sight the fact that this is a carefully conducted and extensively peer-reviewed study. There is a sense in which every research result is always preliminary (I've been a practicing, professional scientist too), but this one isn't a half-baked piece of work by any stretch of the imagination. As such, it is absolutely valid and legitimate to refer to it, despite its results being uncomfortable for materialists.
"Kastrup also makes the simplistic and wrong assumption that intensity of experience must equate to greater brain activity (in the purely materialist model)."
What Novella is referring to here is the notion of proportionality: the idea that the intensity of subjective experience is proportional to the intensity of brain activation. Let me start by saying that I acknowledge the existence of other notions in neuroscience, like e.g. "specificity," according to which specific experiences are associated to specific sub-sets of neurons. Specificity is contradictory with proportionality. Yet, sometimes the data fits better with the notion of specificity, and sometimes with the notion of proportionality. So some materialists use both notions, depending on the evidence at hand, to justify the paradigmatic assumption that the brain generates the mind. In fact, many other mutually-contradictory mappings between objective physiology and subjective phenomenology are often alluded to to substantiate materialism. I wrote about this interesting phenomenon before here (which I hereby add as integral part of this response). So when I alluded to proportionality, I was referring to an explanatory model that materialists do use, and have used when debating me, to justify their position. As a matter of fact, when one uses the ordinarily observed correlations between brain states and mind states to argue for materialism, one is flirting very closely with the notion of proportionality.
Still, Novella's example to counter the notion of proportionality misses the point entirely:
"The massive frontal lobes, however, can have a largely calming effect. They can be furiously active while having the net effect of modulating emotions and experience specifically to make them less “intense,” from a subjective and emotional point of view. Anyone who has dealt with a patient who has had frontal lobe damage (and decreased brain activity) will know this to be true. Intensity of experience does not equal intensity of neuronal firing."
So he is saying that the frontal lobes may have an inhibitory role, so the more they are activated, the lesser the subjective experience. This is because they dampen the activation of other excitatory processes that correspond to the experience. Such effect is an obvious implication of the existence of inhibitory processes; it's what they do. But the point in contention here is whether 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). Novella's example thus fails to address the point in contention.
Having said all this, none of the three scenarios I referred to above, and described in this article, depends on the notion of proportionality (in my argument under scenario 2 I briefly allude to proportionality, but clearly explain why it's not required to invalidate the scenario). So by dismissing proportionality Novella still does not help explain the results of the psilocybin study in contention. For clarity: My argument that the psilocybin study results cannot be explained by materialist assumptions does not depend on the notion of proportionality. I countered proportionality merely in an attempt to be complete in my analysis, since some materialists do conveniently use proportionality as evidence for their position, when the data in contention is conducive to it.
"He should at least exhibit a little tiny bit of humility when confronting neuroscientists about neuroscience"
Truths and arguments stand on their own or fail on their own. Either way, they are not determined by authority, otherwise we would still be living under the notion that the Earth is the center of the universe. I believe I'm arguing objectively and with respect, and that should be sufficient. Now, the fact that Novella is a neuroscientist and I am not, as he so eagerly points out above, should only make it easier for him to destroy my arguments: after all, by his own admission, I am playing with a disadvantage here.
Copyright © 2012 by Bernardo Kastrup. All rights are reserved.