Daniel C. Dennett, From Bacteria to Bach and Back: The Evolution of Minds, W.W. Norton & Company, 2017. [All page numbers in this commentary come from the 2018 paperback edition]
As I have summarized in my previous commentaries about this book, there are some passages that I found ugly in the sense of being snarky personal attacks on scientists and philosophers who disagree with Dennett. There were also some ideas, conjectures, and arguments that I found intellectually stimulating and creative. But these are all too often, at least for my taste, intermixed with passages I found silly, including controversial, sometimes outrageous, claims that are perhaps just games Dennett likes to play to demonstrate how clever he is and/or to sell books. However, my overall assessment of the book is that Dennett’s major thesis has fatal flaws, and that is what I will discuss in this commentary.
The first fatal flaw in Dennett’s thesis stems from his mischaracterization of how causal relationships operate during Darwinian evolution. This is surprising because Dennett has a long history of extolling Darwinian theory, and is almost certainly aware of how Darwin’s theory of natural selection actually works. He provides a direct quote from Darwin on page 137 of his book:
“But if variations useful to any organic being do occur, assuredly individuals thus characterized will have the best chance of being preserved in the struggle for life; and from the strong principle of inheritance they will tend to produce offspring similarly characterized. This principle of preservation, I have called, for the sake of brevity, Natural Selection.” [a quoted passage from Darwin’s Origin of the Species]
This quote is followed on the next page by an enumeration of the three elements that are now accepted by scientists as being required in order for Darwinian evolution by natural selection to take place: 1. Variation of the characteristic in members of the population, 2. which causes different rates of reproduction, and 3) which is heritable. [page 138]
But when it comes time to delineate his own theory of consciousness, Dennett makes confusing claims that are (inexplicably) not compatible with Darwin’s theory. Here is an example:
“Once under way, we became the apes with (meme-)infected brains. … The earliest memes … were not yet domesticated, and they had to be particularly ‘infectious’ until the suite of genes and the memes for enhancing the copying routines were in place…” [page 285]
This is such a mishmash of confused thinking that it is hard to believe Dennett has really given much thought to his own theory. The only way I know to try to disentangle and explain this confused (and faulty) line of reasoning is to first offer a short two-paragraph primer regarding the biological basis of natural selection. Then I will go back and work through Dennett’s (faulty) argument step by step.
There are two kinds of cells in our bodies, somatic and germ. Most of the cells in our bodies, including the neurons in our brain, are somatic. Germ cells are found in our gonads. All the cells in our body (somatic and germ) generally carry the same set of genes, copies of the ones we received from our parents. Once in a while a mutation occurs in a cell that alters one of the genes in that cell. If the mutation happens in a somatic cell, the mutated gene might alter the way the body of that individual functions but will not have any effect on offspring of that individual. The only possible way for an altered gene to be transferred into the next generation is if there is a mutation (altered gene) in one of the germ cells that forms an egg or sperm that is involved in conception
Natural selection only works on the basis of mutations that are carried into the next generation by germ cells. If the mutation confers an advantage to the offspring in terms of survival, then more of these mutated offspring will survive than offspring from individuals who do not have that mutation (on average – we are talking about statistical advantages here). The net effect of this process over many generations is that new mutated genes that increase survival value will spread throughout the population. When sufficient numbers of these new (mutated) genes have accumulated in a population a new species is formed.
A faulty claim that a mutation in a somatic cell will be transferred to the next generation is commonly referred to as being “Lamarkian”, named after a Russian scientist made infamous for this mistake.
Now lets go back and evaluate Dennett’s argument about memes from a biological perspective of how natural selection works. Dennett first tells us that the earliest memes that invaded hominin brains had to be “particularly infectious”. But he makes no attempt to explain why it should be that these particularly infectious memes only invaded the brains of hominins and no other species? The most likely scenario from an evolutionary perspective, the one Dennett ignores because it does not go along with his theory, is that memes invaded hominin brains because their brain cells (germ and somatic) had undergone one or more prior mutations that allowed their brains to react to and communicate with others using memes (words and other cultural entities as outlined by Dennett). In other words, Dennett has reversed the cause and effect that is most likely playing out here. He is trying to promote a theory in which the cause of humans having consciousness is that memes were successful in invading hominin brains. A more plausible explanation would be that brains in hominins, including Homo sapiens, had changed (due to mutations) in such a way that they attained a new function, the ability to process and communicate with others certain kinds of thoughts (the kind Dennett labels as memes), and this kind of thinking led to consciousness.
But let’s give Dennett the benefit of the doubt here. Maybe there really were highly infectious memes floating around before hominin brains carried any mutations that might lead to consciousness. And lets allow that maybe it was simply chance that allowed those memes to invade hominin brains but not the brains of any other species. Based on this scenario, some number of humans would have meme infected brain cells. But brain cells are somatic cells so any changes in brain function caused by these invading memes will never get transmitted to future generations unless there is some mechanism in place to cause mutations of the right kind to take place in germ cells in the gonads.
Here is Dennett’s proposed mechanism for how this might happen. He asserts in the quote shown above that the highly infective memes would simply have to hang out in the brain cells “until the suite of genes and the memes for enhancing the copying routines were in place”. When I first read this passage in the book, I withheld judgment, waiting for Dennett to provide a plausible mechanism by which this might happen. Hundreds of pages later, I finished the book, still waiting. As far as I can surmise, the missing step in the logic of Dennett’s theory is something along the lines, “a miracle happens”. And apparently Dennett himself is aware at some level of understanding that something more is needed to prop up his theory, which is most likely the reason he adds puzzling statements such as:
“and once some of the good habits were in place, there would be time for both cultural and genetic R&D to go back and clean up some of the excesses.” [page 285]
I wish him good luck on working out how that might happen, and when he has accomplished that perhaps he can write another book in which he explains it to us. In his current book, every time Dennett seemingly realizes that his theory is in trouble, instead of trying to fix it, he throws in another curveball such as his assertion that somehow (miraculously?) this will all be resolved biologically,
“in much the way our genetic micromachinery has evolved measures for dealing with the troublemakers in the genome”. [page 285]
I invite anyone who thinks this “apples applied to oranges” solution might work to enroll in a college course in basic molecular genetics and then report back to me after having passed the class.
There are several other examples in the book where Dennett inserts spurious (irrelevant) arguments to deflect attention from fatal flaws in his theory. For example:
“[Some object that] Cultural evolution is Lamarkian. … There is no way for an acquired trait to adjust an organism’s genes so that the trait gets passed along to the next generation genetically. [page 243]
“Maybe these critics are forgetting that in memetic evolution it is the fitness of the memes themselves that is at stake, not the fitness of their hosts. The question of Lamarckianism should be whether features acquired by the memes can be transmitted to their offspring. And here, since the genotype/phenotype distinction that makes Lamarkian transmission all but impossible is absent, Lamarckian transmission would not be a heresy, but just an alternative variety of natural selection—after all, memes don’t have genes.” [page 244]
I guess this notion that cultural memes could participate in something analogous to what happens to biological organisms during natural selection is clever, but the only reason I can discern for inserting that clever (but irrelevant) story here is to deflect readers’ attention from the harsh reality that, unless and until Dennett provides a plausible mechanism for genetic transmission of meme infected biological brains into subsequent generations, his theory is Lamarkian.
I will next move on to discuss a second major problem I have with Dennett’s theory.
User-Illusions in the Cartesian Theater
Dennett describes what he characterizes as being a currently accepted (but he argues, flawed) theory of consciousness. Then he proposes his own new (modified) theory that he claims solves the flaws of the original.
I have quibbles, as I will explain below, but no major disagreements, with Dennett’s critique of what he deems to be a currently accepted theory of consciousness. I have a more serious problem with what Dennett proposes as being the solution.
I will start by describing what Dennett asserts to be a currently accepted theory of consciousness, the theory he labels as “The Cartesian Theater”. One of the peculiarities I discovered early on in Dennett’s book is his use of this term when alluding to Descartes’ concept of “Dualism”, the idea that the body, a physical entity, and the mind, a nonphysical entity, belong to different realms. While reading these passages it was unclear to me what Descartes’ dualism has to do with a “theater”. It was only when I reached near the end of the book where Dennett is analyzing the (well known to psychologists) color aftereffect phenomenon that I realized that he was using the term “theater” in the sense of consciousness being like sitting in a movie theater and looking at images projected by a video projector. Dennett invites readers to demonstrate the color aftereffect for themselves by viewing Figure 14.1 in his book. Viewers typically report seeing a “red stripe”. Dennett comments:
“But think: there are no red stripes on the page, on your retina, or in your brain. In fact, there is no red stripe anywhere. It just seems to you that there is a red stripe. Your brain ‘projects’ a nonexistent red stripe onto the world. (It is important that the illusory stripe doesn’t appear to you to be in your head; it appears to be on the page, as if projected there by a video projector in the middle of your forehead.) [page 358]
Dennett then elaborates three primary arguments to demonstrate what he thinks is wrong with the Cartesian Theater explanation for the color afterimage effect: 1) The cause of your perception of a red stripe is neural activity in the brain, and that neural activity is neither red nor a stripe. 2) This depiction of an image on a screen simply adds an unnecessary step to the process of consciousness. The projector has already formed the image so adding an extra step of looking at the image (which Dennett refers to with a technical term ‘qualia’) is not needed. 3) This way of thinking reflects a classical philosophical error of confusing the ‘intentional object’ (seeing a red stripe) with its ‘cause’, which cannot be a red stripe since none is present in Figure 14.1.
I have no objections whatsoever to any of these arguments. What I will quibble about is the implication by Dennett that the theory he is criticizing is one that is promoted by modern day cognitive neuroscientists. Although he does not call it that, the theory Dennett is debunking is an example of a “Homunculus Theory”, a technical name used by cognitive neuroscientists for the general class of theories of perception that involve having the brain produce images (pictures) that are then viewed by some entity. In Dennett’s version of the theory, the entity supposedly doing the viewing is the “self”. But no mainstream academic cognitive scientist that I am aware of has ever explicitly proposed such a theory. I wrote an academic technical book on the topic of visual perception before my retirement, and that book distilled all of the scientific literature published in peer reviewed journals prior to that date. Here is how I summarized the status of Homunculus Theories in that book:
“Homunculus solutions to the problem of how activities in our brain get conveyed to our mind propose that this is accomplished by a little person inside our head. Our eyes and optic nerves function to form a picture in our brains of ‘what is out there’. Then the homunculus looks at the picture and what it sees provides our perceptual experiences.
The idea of a ‘little person in the head’ seems silly when we state it formally and explicitly. Furthermore, the basic notion of a homunculus was rejected by philosophers a long time ago on logical grounds because it leads to an infinite regress. There would have to be another little person inside the head of the homunculus to interpret the picture in its brain, etc., etc., ad infinitum.
However, our everyday thinking about perception often includes an implicit notion that there is a little person in our heads that accounts for our percepts. Similarly, many biologically based theories of perception, when they are made explicit, also end up either being some form of a homunculus theory or having similar philosophical problems. For example, neuroscientists have been able to demonstrate that various brain regions contain neural representations of the visual environment. An examination of the properties of these neural representations is valuable in terms of trying to address questions about how sensory information is coded as it is processed in the brain. However, when evaluating the significance of these neural representations to perceptual processing, we need to be careful not to be lulled into thinking that these provide an explanation for subjective perceptual experience. Such thinking only makes sense if we have adopted an explicit or implicit homunculus theory of perception. It makes no difference whether a picture is present in the brain unless there is someone present to look at it.
[Ronald G. Boothe, Perception of the Visual Environment, Springer-Verlag, 2002, page 9, https://link.springer.com/book/10.1007/b97382#toc ]
So, although I might quibble with Dennett about whether the kind of theory he is critiquing is really one that is explicitly promoted by cognitive neuroscientists, I agree with him that these kinds of theories are essentially worthless. And they do unfortunately sometimes appear, implicitly, in neuroscience textbooks and in the neuroscience literature by authors who have not thought carefully enough about the topic.
Let’s examine next how Dennett proposes to fix the problems associated with this “Cartesian Theater Homunculus theory”. He simply eliminates the theater and replaces it with neural activity in the brain. My response is ‘bravo!’, but this is not a novel idea. I, along with essentially one hundred percent of modern day cognitive neuroscientists, would agree with the assertion that what causes our subjective conscious perceptions is neural activity in our brains. The disagreement with Dennett has to do with whether or not this assertion is a solution to the problem of consciousness. Ironically, what Dennett is proposing as a solution is identical to what contemporary cognitive scientists characterize as the hard problem of consciousness that needs a solution.
Theories that make claims that neural activity in the brain is responsible for causing subjective conscious experiences are sometimes referred to as “Bridge Locus Theories” because they propose that specific physical structures (in this case neurons in the brain) provide a bridge from the physical body to the nonphysical mind. Here is how I characterized these theories in my 2002 book:
Bridge locus solutions to the mind-body problem take seriously the idea that it is the brain that causes our conscious perceptual experiences and designate specific structures(s) in our brain as being responsible. These neural correlates of consciousness are assumed to have some privileged, and as yet mysterious, causal powers that allow conscious perceptual experiences to be produced. [ibid, page 9]
In other words, I agree with Dennett that the brain causes our conscious perceptual experiences, but think it is an unsolved (and currently mysterious) problem to understand how this happens. When cognitive neuroscientists like myself refer to the “hard problem of consciousness” we are referring to the problem of how to account for the fact that physical activities in our brains can cause “subjective conscious experiences”. Dennett, for reasons that are inexplicable to me, does not use the phrase “subjective conscious experiences” when describing the problem he is trying to solve. Instead, he uses terms such as false beliefs, judgments, or convictions. Here are some examples of Dennett’s own descriptions of the “problem” he thinks his own theory is addressing:
“[When we ask someone what they see] we create an artifact. What our questions directly create, or provoke, are answers … What they indirectly create are ideologies based on those answers. You can ask yourself what your subjective experience is and see what you want to say. Then you can decide to endorse your own declaration … You can do this by talking aloud to yourself, talking silently to yourself, or ‘just thinking’ to yourself about what you are currently experiencing. That is the extent of your access to your own experience, and it does not differ much from the access another person can have of those experiences—your experiences—if you decide to go public with your account.” [page 350]
“you misinterpret your sense (judgment, conviction, belief, inclination) that your seeing a red stripe is arising from a subjective property (a quale in the jargon of philosophy) that is the source of your judgment, when in fact, that is just about backward. It is your ability to describe ‘the red stripe,’ your judgment, your willingness to make the assertions you just made, and your emotional reactions (if any) to ‘the red stripe’ that is the source of your conviction that there is a subjective red stripe.” [page 358]
“[the explanation for the color aftereffect is that the stimulus] fatigues the relevant neural circuits in the complementary color system, which then generate a false signal … [so that] somewhere fairly high in the process betwixt retina and, um … the philosophical conviction, a red stripe shaped quale is rendered, and it is the appreciation of this quale that … underwrites the philosophical conviction that right now you are enjoying a stripe-shaped red quale. [page 362]
I can only respond to Dennett by drawing on my own personal experience. Consider the following situation. I have been dozing while lying on my back on the grass in a park on a bright sunny day. As I start to awaken into consciousness and first open my eyes I have an immediate private subjective conscious experience of blue. Only later as I am more fully awake, if ever, do I start having thoughts, internal conversations with myself along the lines, I believe I am lying on my back in the park looking at the blue sky, or conversations with others about my experiences. But, and this is my main point, I had the private subjective conscious experience of blue before any of these thoughts, beliefs, convictions, or conversations with someone else occurred.
Dennett disagrees with my description of what happened. According to him all I had was a belief that I had viewed an image of a blue sky, and that belief might have just been a false belief (a delusion) based on a user illusion. He thinks that once I realize these beliefs are just delusions, any problems with understanding conscious experiences are resolved. Here are some of the arguments Dennett makes about this issue in his own words:
“Curiously, then, our first-person point of view of our own minds is not so different from our second-person point of view of others’ minds: we don’t see, or hear or feel, the complicated neural machinery churning away in our brains but have to settle for an interpreted digested version, a user-illusion. [page 345]
“There is a long-standing tradition to the effect that somehow [the phenomenology of one’s own experience] is a more intimate, more authentic, more direct way of getting at the objects of experience that adopting the ‘first-person point of view’ is the key strategic move in any promising study of consciousness, but that is itself a delusion.” [page 351]
“Doggedly pursuing the idea that qualia are both the causes and the intentional objects … leads to further artifactual fantasies, the most extravagant of which is the idea that unlike our knowledge of all other kinds of causation, our knowledge of mental causation is infallible and direct: we can’t be wrong when we declare that our subjective beliefs about the elements of our conscious experience are caused by those very elements. [page 363]
So, we have two different accounts of personal experience. My own impression that the private subjective conscious experience came first and the formation of beliefs about that experience that can be publicly shared only came afterward. And Dennett’s account that my private subjective experience is just a false belief based on a user-illusion.
I will give Dennett the next to last word:
You might be a zombie … but I know that I am not a zombie: No, you don’t.” [page 363]
But I will use my author’s prerogative to have the last word:
I think one of us might be suffering from delusions (perhaps of grandeur).
Ron Boothe, email@example.com