Daniel Dennett and the hard problem of consciousness
Daniel Dennett died three days ago on 19 April at the age of 82. Dennett was a controversial philosopher whose writings on consciousness argued that consciousness was an illusion created by the brain. His 1991 book Consciousness Explained was an important contribution to the debate among philosophers and neuroscientists on the nature of consciousness.
I’ve had a longstanding interest in the nature of consciousness that resulted in over a decade of Zen meditation practice, including one or two week long silent retreats a year, under the guidance of several Zen masters. More recently, I’ve also been exploring other forms of first-person exploration including breathwork and psychedelics as well as continuing a meditation practice.
While I’ve read a number of articles over the years about what philosophers and neuroscientists have to say about consciousness, I decided to read some of key books in this area to see what they had to contribute. One of the first of these I read was Daniel Dennett’s Consciousness Explained.
His first chapter starts with the brain in the vat. He argues that the creation of all the inputs needed to fool the brain in the vat they were having real experiences is simply computationally impossible, due to the massive number of scenarios requiring inputs. And also claims that hallucinations are rarely “deep” in the sense of being solidly realized hallucinations that the person can interact with, walk around, view from different angles etc.
He seems to have a very limited understanding of the range of hallucinogenic experiences that people have, or for that matter, lucid dreams in which they can have detailed interactions, conversations etc with other dream characters and interact in detail with their dreamscape, including changing and influencing it. He does have some interesting thoughts on how dreams can be randomly generated in a way which means they reflect the concerns of the dreamer, but have no “internal author”.
He later goes on to explain how brain processes use partial sensory information to fill in what we perceive as perceptions without gaps and holes. He goes to some length to explain how this could be done simply by creating the memory that it was done rather than that the brain has to construct a detailed “film” to be played in an internal “Cartesian theatre” for the mind to view it. Yet does not seem to twig that exactly this process can operate to create what we experience as extremely solidly realized hallucinations.
The book is around 500 pages in length and the bulk of it is about brain processes and how they construct our perceptions from partial inputs. He doesn’t really get to address the hard issues re consciousness until the last three chapters.
For example, Dennett discusses how we see a continuous visual field with no blind spot. Is the brain taking the visual input and “filling in” the blind spot? There are various other perceptual issues where what we “see” is minus the missing data in the visual input. It seems fairly obvious to me that the brain simply has an instruction to ignore the missing stuff, or more correctly, without any actual input from that part of the field it simply ignores it, and we are unaware anything is missing. And after about 10 pages of discussing the issues with “filling in” he gets there. Perhaps I’ve picked up the solution to this question from more recent writing, and he is simply writing before much of this was explored.
But it is yet another example of how most of his quite lengthy book is devoted to discussing how the contents of consciousness are created, not discussing consciousness itself. His book was written before Chalmers in his 1996 book invented the term “hard problem of consciousness” and brought a lot of attention to it. He does address this issue in the last part of the book, and as I discuss below seems to completely dismiss it on the grounds that consciousness is an illusion.
Dennett is one of those infuriating philosophers who think that whatever half-baked assumption he has about the world can be stated as an obvious truth from which he then draws entirely unwarranted conclusions. For example, in Chapter 3 he tells us that most animals other than cats and dogs cannot enjoy what they do, and as an example says that birds cannot enjoy the sensation of flight. He goes on to conclude that humans are the only animals that can do things purely to have fun.
In Chapter 10, he tells us that the hallmark of consciousness is that they can be reported (barring aphasia, paralysis, or being bound and gagged). The exceptions in brackets are his. So he then concludes that conscious states must be accompanied by suitable higher-order thoughts. Apart from being a non-sequitur, he seems completely unaware of the extensive reporting of states of consciousness by humans which were not accompanied at the time by higher-order thoughts. In fact, I drop into such a state sometimes while meditating, when all thoughts may drop away for a period.
In Chapter 12, Qualia Disqualified turns to a discussion of qualia (for example the subjective experience of a colour). He makes the point that the affective or emotional properties of red are to a large extent programmed into the brain by evolution (red is universally a colour that alerts, perhaps because it is so different to the normal blue-green of the natural environment). And the subjective response to red is not only a result of programmed instincts, but also of individual associations and quirks. He concludes that qualia for redness are JUST those complexes of dispositions evoked by the perception of “red” light. To quote:
“You seem to be referring to a private, ineffable something-or-other in your mind’s eye, a private shade of homogeneous pink, but this is just how it seems to you, not how it is. That “quale” of yours is a character in good standing in the fictional world of your heterophenomenology but what it turns out to be in the real world in your brain is just a complex of dispositions.”
The phrase I have italicized astonishes me. “Just how it seems to you” is exactly what qualia refer to, the subjective individual experience of red. But apparently this is “Not how it is”, as presumably that is the set of brain reactions and instincts triggered (a complex of dispositions that can in principle be at least partially observable by another person).
But! Qualia ARE the subjective experience, not the objective dispositions of the brain. Qualia are observed from the inside and indeed are exactly “just how it seems to me”, not the chemical and electrical processes of the brain “observed from outside”. Here Dennett is essentially dismissing the whole experience of first person consciousness as “fictional” and what is real is the associated objectively observable phenomena.
He doubles down on this position by claiming that the qualophile will claim that the quale red could be changed without changing any of the associated dispositions. This is entirely beside the point. I would not make that claim, the inside and outside of something are not independent. But the fact that a change in the experience of a quale will likely be associated with some change in the brain functioning does not mean the first-person experience is a fiction (or non-existent) and all that is real is the third-person observations of brain states.
Now that he has concluded that qualia do not exist, it is not surprising that he further concludes that there is no hard problem of consciousness, and “philosophical zombies”, which are supposed to act like a human in every way while somehow lacking qualia, cannot exist. In his 1996 book, David Chalmers argues that Dennett’s position is essentially a denial of consciousness and, perhaps jokingly, suggests that Dennett is a philosophical zombie.
Dennett spends quite a bit of time making the point that qualia are epiphenomenal in the philosophical sense that they are an effect which itself has no effects in the physical world. This implies that things would happen in exactly the same way without them. Hence there is no empirical reason for believing in them. His sleight of hand here is slip in the “empirical” which is a reference to external third-person observations. The first-person experience that we all have is completely dismissed. If anything, his argument is a valid argument that we cannot tell whether someone else is a zombie or not. But for him, the “not” is not an option because qualia have been shown by him not to exist.
To quote Dennett directly “Are zombies possible? They’re not just possible, they’re actual. We’re all zombies*. Nobody is conscious…..I can’t prove that no such sort of consciousness exists. I also cannot prove that gremlins don’t exist. The best I can do is show that there is no respectable motivation for believing in it.” The asterisk indicates a footnote in which Dennett says it would be an act of desperate intellectual dishonesty to quote this assertion out of context. I think I have provided enough context!
To respond: it may not be “respectable” in some academic philosophical circles, but first person consciousness is intrinsic to my entire experience of reality, including the objective third-person observations which Dennett thinks are the only real aspect of reality.
In a somewhat refreshing interlude in Chapter 13, Dennett addresses the reality of the sense of being a “self” and concludes that it is a brain construct. His arguments are an extrapolation from his discussions of brain processes with no apparent awareness of the fact that many people have had direct experience of “no-self”. He asks the question “are there conditions under which life goes on but no self emerges? Are there conditions under which more than oneself emerges? We can’t ethically conduct such experiments.” In fact, we can. Meditation, psychedelics, breath work and other practices can provide ethical experiments for altering brain states and consciousness. I have experienced the loss of a sense of self in meditative states, and I have experienced the emergence of multiple selves and radical changes in the sense of self while on psychedelic journeys. But that is for another post. And experiments with split-brain patients do seem to provide evidence there are two independent centres of consciousness operating, likely with separate senses of self.
In the final chapter, Dennett attacks those who argue that its not possible to imagine how a software program running on a machine could become conscious. Dennett argues that any program complex enough to simulate conscious interaction with humans will be no different to humans (whose brain processes are all that is going on, and these are the equivalent of very complex programs). I remain totally unconvinced. He is completely dodging the hard question of the emergence of consciousness from non-conscious inputs. He also dismisses the possibility that it is impossible to imagine what its like to be a bat. Here, I am actually fairly sure Nagel was referring to the possibility of knowing (not imagining) what it was like to be a bat.
On the topic of consciousness itself, he really doesn’t explore any of the evidence on consciousness from first-person explorations through meditation, psychedelics, breath work, etc. Dennett finishes the book claiming he has shown how consciousness is an illusion that can be explained in terms of unconscious events. Nope, not even close. As Annaka Harris has pointed out, consciousness is the one thing that can’t be an illusion — by definition. “An illusion can appear within consciousness, but you are either experiencing something or you’re not — consciousness is necessary for an illusion to take place.”
The Wikipedia article on Consciousness Explained, quotes critics as saying that “Dennett is denying the existence of subjective conscious states, while giving the appearance of giving a scientific explanation of them.” Dennett’s views seemed to have remained fairly consistent in later books and papers, and I have only looked at a little of his later work. According the Guardian in its obituary for him, in recent years he became more lenient towards mental states being more than just brain states. He has more recently described himself as “a mild realist” about mental states, that they are not merely something fully described by third-person observers. But in my brief overview of more recent discussions of his position by other philosophers, they appear to be somewhat unclear about whether this represents a real shift towards accepting that consciousness is not just an illusion.
In summary, I found the book unconvincing, disappointing, and dated. He does have some interesting discussions of neuroscience research relating to how the brain creates the contents of consciousness. But as the book was written in 1991 and there has been a huge increase in our understanding of brain processes in the decades since, this is not the book I would read for the neuroscience of how our brain processes perceptions for us to experience.
An earlier version of this article was published on my blog here.
