The difficulty of explaining consciousness, that has flummoxed the best minds of our species, remains elusive but has long reached the point where the flawed, misguided and just plain wrong, ideas of the past should be laid to rest. With that, and the difficulty of the subject, in mind, the ambitiously-titled Consciousness Explained offers a thorough but challenging introduction to the issues of the problem and may point the way to the solution. Written by that science-friendly philosopher-writer of acclaimed books for the spare time intellectual – Daniel Dennett.

Understanding consciousness is one of the most enduring intellectual problems in human history. For most of that history it has been a problem tackled by philosophers but, more recently, it is a problem being attacked on multiple fronts including psychology and neuroscience as well as insights from the development of artificial intelligence.

Dennett describes Consciousness Explained as the culmination of 30 years of thinking about consciousness. He felt he had reached a point where he could sketch an outline of a solution; a theory of consciousness that, even if not complete or free from error, can at least add to our knowledge and point the way to better answers. Divided into three parts, in the first Dennett lays out the key problems of consciousness and the history of attempts to solve them. The second part presents Dennett’s empirically-based theory and the third shows how his model holds up against some of mysteries of consciousness.

Even if you have not educated yourself in the technicalities of the problems of consciousness, you are probably aware of the problem that has dominated the history of the subject – the mind-body problem. Is the mind part of the body, presumably the brain? Or is it something separate from the body/brain? Some immaterial thing, Descartes’ ‘ghost in the machine’, similar to the concept of a soul?

Dualists – those who argued for the latter; a separation of mind and body – have fallen out of favour in modern times. While Dennett does not give a comprehensive takedown of the arguments for dualism, he does bury it early in Part One and gives his reasons for why a theory of consciousness would best avoid dualism. To Dennett, dualism’s most fatal flaw is that it violates the conservation of energy. Given that, what more is there to say?  That being said, Dennett warns that the alternative – materialism; the argument that the mind is [part of] the brain – still has some major hurdles to overcome. The most obvious being that nowhere in the brain is consciousness housed, nowhere does everything come together and consciousness happen – the ‘Cartesian Theatre’.

And the trouble with brains, it seems, is that when you look into them, you discover that there’s nobody home. No part of the brain is the thinker that does the thinking or the feeler that does the feeling, and the whole brain seems no better a candidate for that very special role. This is a slippery topic. Do brains think? Do eyes see? Or do people see with their eyes and think with their brains? Is there a difference? Is this just a trivial point of “grammar” or does it reveal a major source of confusion? The idea that a self (or a person, or, for that matter, a soul) is distinct from a brain or body is deeply rooted in our ways of speaking and hence our ways of thinking.

But before we even get there, there are plenty of other problems that need to be overcome – the limitations of language in describing what we experience in our heads and the assumption that we are all describing the same things when we do; whether we can construct an objective scientific theory from studying subjective ‘mental events’; the difficulties of experimenting on people.

There are circumstances in which people are just wrong about what they are doing and how they are doing it. It is not that they lie in the experimental situation, but that they confabulate; they fill in the gaps, guess, speculate, mistake theorising for observing. The relation between what they say and whatever it is that drives them to say what they say could hardly be more obscure.

Once Dennett addresses these issues he is ready to take down the materialist Cartesian Theatre and replace it with his own materialist alternative – the Multiple Drafts model, which Dennett argues allows for consciousness without requiring some master arena to collect and edit the input to provide consciousness.

It is tempting at this point to try and explain Dennett’s model with an analogy. But analogies are problematic because, for what they provide in easy comprehension, they can lead us astray in the details. Despite that, Dennett frequently uses analogies in Consciousness Explained, much to the readers benefit, but, unlike me, he knows the subject intimately enough to use them precisely. So, rather than risk leading you astray, I will share Dennett’s partway definition of his Multiple Drafts model from partway through the book:

There is no single, definitive “stream of consciousness”, because there is no central Headquarters, no Cartesian Theatre where “it all comes together” for the perusal of a Central Meaner. Instead of such a single stream (however wide), there are multiple channels in which specialist circuits try, in parallel pandemoniums, to do their various things, creating Multiple Drafts as they go. Most of these fragmentary drafts of “narrative” play short-lived roles in the modulation of current activity but some get promoted to further functional roles, in swift succession, by the activity of a virtual machine in the brain. The seriality of this machine (its “von Neumannesque” character) is not a “hard-wired” design feature, but rather the upshot of a succession of coalitions of these specialists.

The basic specialists are part of our animal heritage. They were not developed to perform peculiarly human actions, such as reading and writing, but ducking, predator-avoiding, face-recognising, grasping, throwing, berry-picking and other essential tasks. They are often opportunistically enlisted in new roles, for which their native talents more or less suit them. The result is not bedlam only because the trends that are imposed on all this activity are themselves the product of design. Some of this design is innate and is shared with other animals. But it is augmented, and sometimes even overwhelmed in importance, by microhabits of thought that are developed in the individual, partly idiosyncratic results of self-exploration and partly the predesigned gifts of culture. Thousands of memes, mostly borne by language, but also wordless “images” and other data structures, take up residence in an individual brain, shaping its tendencies and thereby turning it into a mind.

Dennett then takes the Multiple Drafts model for a test spin, showing how it damages the credibility of both dualism and the Cartesian Theatre but warns that there are tougher tests to follow. Before we get there though, the book takes a detour to discuss ideas on how consciousness may have evolved. To me this was the most fascinating and, not unrelatedly, the most comprehensible part of the book.

Returning to the difficulties of explaining consciousness, Dennett shows the reader that, beyond dualism and the Cartesian Theatre, there are still more illusions that need to be destroyed. Such as the ‘central meaner’ and the idea that brain structure is specialist and functional and not generalist and multi-functional or that it can’t be both simultaneously. There are also more phenomena that need explanation, like where does speech and meaning come from, or how do we explain ‘blindsight’ where a person can correctly guess what is in their blind spot?

Before a final summation of the ideas contained in the book, Dennett examines what his model of consciousness may mean for the concept of the self. He shares a spirited essay on the evolution of the self from a biological boundary line to an extended phenotype. He shows how his models deals with issues of the self from split brains to multiple personality disorder.

All through the book Dennett utilises various phenomena that can shed light on the workings of the brain and consciousness – dreams, hallucinations, illusions and phantom limbs; paradoxes and perplexities of speech, memory and visual perception. He explores the ideas of many great thinkers – Descartes obviously, but also Freud, Alan Turning, David Hume, John Locke, John von Neumann and Richard Dawkins. As well as many experts that are less well known to the general reader – Thomas Nagel, Gerald Edelman, John Searle, Jerry Fodor, Douglas Hofstadter and many others. He sees this work as a consolidation of the strengths of various fields from neuroscientists, cognitive scientists, psychologists, philosophers and from artificial intelligence but without ‘engaging in their flaws or politics’.

Now, I like to think of myself as a fairly intelligent person(!). I have some evidence to back that up. As far as reading goes, I have read, and I think, understood, some books that I know other intelligent people have had difficulty with. Like The Selfish Gene or A Brief History of Time. I say all this not to boast but in the hope that it will emphasise my point – I found this book very difficult!

Some of its difficulties are for reasons you might guess and that would be common to other books on consciousness – it is a very difficult subject, with complex ideas and there are unfamiliar terms to learn and problems and potential solutions that are hard to grasp. But the nature of the subject and how it needs to be tackled means that you may not appreciate how difficult it is until you are in there tackling it. Minding your mind while thinking about thinking is very challenging to the uninitiated general reader. Consciousness has been a problem people have duelled with for a long time with a lot of complex and convoluted thinking and ideas. That makes for a lot of wrong ideas that need to be properly discredited.

Another problem is that dualism and the Cartesian Theatre are very difficult to dismiss even if you are convinced that they should be. For me, the Cartesian Theatre was especially stubborn. I felt like a person from the stone age being told he has to get rid of the idea of a flat Earth or a geocentric universe. I could accept the flaws and evidence readily, but it feels so hard-wired into my brain and my sense of intuition that, if I am not vigilant, it keeps coming back. Often what seems reasonable, intuitive and conforms to experience, turns out to be wrong, while an alternative – even if it is not completely right – that avoids the problems of the wrong idea is often difficult to understand, feels unsatisfying and requires the submission of intuition to evidence. Such is science!

It is very hard to imagine how your mind could be your brain – but not impossible. In order to imagine this, you really have to know quite a lot of what science has discovered about how brains work, but much more important, you have to learn new ways of thinking. Adding facts helps you imagine new possibilities, but the discoveries and theories of neuroscience are not enough – even neuroscientists are often baffled by consciousness. In order to stretch your imagination, I will provide, along with the relevant scientific facts, a series of stories, analogies, thought experiments and other devices designed to give you new perspectives, break old habits of thought, and help you organise the facts into a single, coherent vision strikingly different from the traditional view of consciousness we tend to trust.

Time and again, Dennett would share an idea that appealed to my intuition, and I would enjoy a momentary sense of clarity, only for Dennett to say, ‘If you find this conclusion compelling, you are still locked in the Cartesian Theatre’.

The idea of a special centre in the brain is the most tenacious bad idea bedevilling our attempts to think about consciousness. As we shall see, it keeps reasserting itself, in new guises, and for a variety of ostensibly compelling reasons.

The further problem is that, aside from ideas from the past, there are now many complex psychological and neurological paradoxes and phenomena that have been discovered and that any theory of consciousness needs to adequately deal with. And on top of that there are many clever thought experiments that turn out to be misleading but in very subtle ways. And that’s back when this book was written in the early 1990’s. Coming to grips with each of them and understanding how his model deals with them is another layer of difficulty.

All of these, though, are difficulties with the subject matter, not problems with the book or Dennett’s writing. Consciousness Explained does all the above within a shortish book given its subject and aims; around 470 pages. Which makes it a book that demands you study it rather than merely read it. It probably should be put down for a few days at a stretch so the reader can fully come to terms with each idea that is new to them. I probably should have got a better grasp of heterophenomenology before pushing on with reading the book. I did have to keep going back and reminding myself of the distinctions between Orwellian and Stalinesque revisions, between Bureaucratic and Pandemonium models. I did find myself reading past ideas I did not fully understand simply because I wanted to read and did not want to study. That was my fault.

Right now this model probably makes little sense to you as a model of the consciousness you know from your own intimate experience. That’s because you are still so comfortable thinking about your consciousness as taking place in the Cartesian Theatre. Breaking down that natural, comfortable habit, and making the Multiple Drafts model into a vivid and believable alternative, will take some work, and weird work at that.

The only fair criticism of this book that I can feel confident in offering is that, published in the early 1990’s, it is perhaps somewhat aged. Many of the ‘new’ and ‘recent’ developments referred to in the book occurred in the 1980’s. No doubt, much else can be added to the debate if it were written today, especially in the field of artificial intelligence. Nevertheless, Consciousness Explained may remain a useful resource for beginners to the problem of consciousness for its laying out of the heart of the problem and its jousting with stubborn antiquated ideas.