As you read this page, you are having a visual experience of black letters against a white background. You can probably hear background noises: traffic, distant conversation, or the faint hum of a computer. You may be experiencing strong smells or tastes: the smell of coffee, the taste of mint as you chew a fresh piece of gum. Maybe you feel some emotions: a feeling of excitement, or sadness, or maybe you just feel a bit tired or distracted. If you pay attention, you will notice more subtle kinds of experience: the tactile sensation of the chair against your body, perhaps sensations of itchiness or throbbing in a knee or an arm. These are all forms of conscious experience. They are states that characterize your subjective inner life. These feelings and experiences make up what it’s like to be you.
Consciousness is fundamental to what we are as human beings. This is not to undermine the importance of the body: we are embodied creatures and we relate to one another through and with our bodies. But it is consciousness that defines the identity of the person. Fundamentally we know a person in terms of their feelings and thoughts, and the quirks of their personality. Perhaps one day in the future it will be possible to survive the death of the body by uploading one’s mind onto a computer, making it possible to talk to grandma via email long after her body has rotted in the ground. So long as the conscious mind survives, we feel that the person has survived. In contrast, when the conscious mind has gone, for example, in tragic cases of permanent coma, the living body can seem nothing more than a memorial to the person who once was.
Consciousness is also the source of much that is of value in existence. Without consciousness, the universe would still be just as immense and awe-inspiring. But without a conscious mind to appreciate its majesty, is there really any value in the existence of all that stuff? It is our experiences that make life worth living: exhilarating pleasures, sweeping emotions, subtle thoughts. Without consciousness none of these things is possible.
As well as being the ground of our identity and a source of great value, consciousness is the only thing we know for certain is real. I can’t know for certain that there really is a world out there. Perhaps I’m actually in the Matrix, naked and hairless, encapsulated in a vat of chemicals being fed information about a nonexistent virtual world by computers that are using me as an energy source. I might not even have a body: perhaps the computers disposed of my body long ago and now all that remains of me is a brain wired up to a computer. Or perhaps I am myself a computer, created by humans to think that I am a living human being.
But there is one thing I know for certain: I exist as a conscious being. If I am in the Matrix, the computers might be deceiving me about all kinds of things, but they can’t be making me think I’m conscious when I’m not. Perhaps my visual experience of the room around me doesn’t correspond to anything real, but I know I am having a visual experience nonetheless. The only thing I have direct access to are my own experiences. Everything else is known indirectly, believed on the basis of what I experience. All knowledge of reality is mediated through consciousness.
This was the insight of the father of modern philosophy René Descartes (1596–1650), summed up with his famous line “Cogito ergo sum” or “I think, therefore I am.” This phrasing is potentially misleading. Descartes wasn’t saying that he exists because he thinks. (Hence the following old joke doesn’t really work: Descartes goes into a bar. Barman says, “Want a beer?” Descartes replies “I think not” and disappears.) Descartes’s point is about knowledge: he knows for certain that he thinks—or more broadly that he is a conscious being—and in knowing this he thereby knows that he exists. The certain knowledge of one’s existence as a conscious being was, for Descartes, the starting point of all knowledge.
Nothing is more certain than consciousness, and yet nothing is harder to incorporate into our scientific picture of the world. We now know a great deal about the brain, much of it discovered in the last eighty years. We understand how neurons—the basic cells of the brain—work in terms of their underlying chemistry. We know the function of many regions of the brain, in terms of processing information and negotiating sensory inputs and behavioral outputs. But none of this has shed any light on how the brain produces consciousness.
Some people dismiss this as simply reflecting the fact that the physical science of the brain—neuroscience—has a long way to go. But if explaining consciousness is a work in progress, one might reasonably expect neuroscience to have yielded a partial explanation of consciousness, accounting for some human experiences but leaving trickier cases unexplained. The reality is that, for all its virtues, neuroscience has thus far failed to provide even the beginnings of an explanation.
This is all the more extraordinary when we contrast it with the great progress science has made in explaining other phenomena. The scientific story of water or gasoline explains the observable characteristics of these substances. We get a satisfying account of why, for example, water boils at 100 degrees centigrade or of why gasoline is flammable. Our scientific understanding of genes continues to provide ever greater insight into how certain traits are passed on from generation to generation. Astrophysics is able to explain how stars and planets are formed. In all of these cases we find satisfying explanations. And yet our increased understanding of the electrochemical processes of the brain has failed to yield insight into how those processes give rise to a subjective inner world.
Physical science has a dismal track record in explaining consciousness. But the track record of physical science in explaining pretty much everything else is impressive. Many scientists and philosophers take this to be good evidence that, in spite of current disappointments, neuroscience will one day crack the mystery of consciousness.
The neuroscientist Anil Seth makes an analogy to life.1 It used to be thought that life was an inherently mysterious phenomenon, which could be explained only via the postulation of mysterious nonphysical “vital forces.” Few people these days take this view, known as “vitalism,” seriously. According to Seth, this was not because some philosophers solved “the problem of life.” We moved on from the days of vitalism because biochemists, instead of dwelling on the mystery, got on with the job of explaining the properties of living systems—metabolism, homeostasis, reproduction, etc.—in terms of underlying mechanisms, and eventually the sense of mystery dissipated.
Seth urges us to take a similar approach to consciousness. It’s what we might call the “Get out of the armchair and into the lab” approach. Seth recommends that instead of dwelling on why consciousness exists in the first place, we should rather focus on what he calls the “real” problem of consciousness: the challenge of mapping correlations between what goes on in the brain and what is experienced by the person. Seth predicts that, just as in the case of life, the sense of mystery will eventually go away and scientists of the future will wonder what the philosophers were worrying about.
The trouble with picking examples from the history of science is that there are always other examples that prove the opposite point. Seth focuses on the scientific challenge of explaining life as it currently exists. But consider instead the riddle of explaining the historical origins of complex life. Before Darwin, it was a mystery where complex, self-replicating organisms came from. The nineteenth-century philosopher William Paley argued that the only plausible hypothesis was that they were created by an intelligent designer, that is to say, by God.2 Paley argued for this with the following analogy. Imagine you’re walking along a beach and you come across a watch lying on the ground. It would be crazy to suppose that something so complex had come about by a chance, random process, and so you would naturally assume that somebody had designed it. Similarly, argued Paley, given the great complexity of living organisms, we should suppose that they too were designed rather than that they came about by chance.
You might think at first this case is quite similar to Seth’s. In both cases what was once taken to be the product of mysterious nonphysical interventions in the natural world came to have a scientific explanation. But there is an important difference. As Seth says, the problem of explaining life as it currently exists—the problem which led some in the nineteenth century to postulate nonphysical vital forces—was not solved by some great insight that pointed toward a solution; it just eventually stopped seeming like a real problem in the first place. But the problem of explaining the historical origins of life was solved by just such an insight. Darwin didn’t just say, “Stop wasting time worrying about where life came from and get on with more serious scientific questions”; rather he came up with the principle of natural selection to explain how complex life emerges. Darwin agreed with Paley that the emergence of complex organisms can’t possibly have happened by chance, but rather than appeal to God he postulated the “blind watchmaker”—to use Richard Dawkins’s memorable phrase—of natural selection in order to explain it.3
Coming back to the problem of consciousness, it seems that it could go either way. Perhaps Seth is right that as we learn more about the brain we will eventually stop worrying where consciousness came from (although there is no sign of this happening yet). But it could equally be that the “Darwin of consciousness” will come along and solve the problem of consciousness in a satisfying way. In opposition to Seth, I will try to show not only that there is good reason for taking the problem of consciousness seriously, but also that there are already the makings of a theoretical framework that could bring about progress.
One of the most vociferous proponents of the “Get out of the armchair and into the lab” approach is the neurophilosopher Patricia Churchland. Imagine, if you can, a fearsome firebrand preacher but for the cause of neuroscience rather than religion, and you’re probably on the right track. Patricia Churchland and her husband, Paul, achieved academic fame in the 1990s for defending a radical position known as “eliminative materialism.” Paul and Patricia argued that we should not be trying to explain the mind but rather rejecting its very existence. Like fairies and magic, science has shown that mental phenomena simply do not exist.4
Here’s an analogy. What people used to think of as demon possession we now know to be epilepsy. But we don’t say, “Great, we now have a scientific explanation of demon possession.” Instead, the scientific explanation has displaced the demon possession explanation, proving beyond reasonable doubt that demon possession does not exist (or at least it’s not what’s going on in standard epilepsy cases). Similarly, the Churchlands claimed that our old-fashioned explanations of human behavior in terms of things like “thought,” “desire,” “hope,” “love” were becoming outdated. They looked forward to a day when we would drop such an antiquated vocabulary altogether and talk about human behavior in terms of its real causes: electrochemical processes in the brain. (One can’t help wondering whether the Churchlands’ early courtship involved poetry expressing the strength of their neuronal activations for each other….)
I am very much open to the idea that scientific progress can show that many of our commonsense ways of thinking about the world are wrong. Modern science has revealed to us that objects we think of as solid are in fact mostly empty space, given the immense distances between the nucleus at the center of the atom and the electrons that orbit it. Einstein’s theory of relativity entails that our commonsense notion of absolute time is an illusion. And, as we shall explore in the next chapter, quantum mechanics has undermined many of our commonsense ways of thinking about matter. However, there is a limit to this. One thing that science could never show is that consciousness does not exist.
Imagine reading the following story in the New Scientist magazine:
Scientists Discover That Consciousness Is an Illusion
For millions of years humans have believed that they have feelings and experiences. In a shocking development, neuroscientists at the California Institute of Technology have discovered that nobody has ever felt or experienced anything. Dr. Ivor Cutler is team leader on the project:
“We are not disputing any of the commonly known facts about human behaviour; nobody could deny, for example, that people scream when their body is damaged. But the popular belief that bodily damage is accompanied by a feeling of pain is in fact an illusion. Feelings are no more real than the Loch Ness Monster.”
Lawyers have been discussing the possible impact of this new discovery on human rights legislation.
We would never, and should never, accept such claims. And this is because our scientific knowledge of the world is itself mediated through conscious experience. We are able to perform observations and experiments only because we have conscious experience of the world around us. In this sense, scientific knowledge is dependent on the reality of consciousness. Science could no more prove that consciousness does not exist than astronomy could prove that there are no telescopes.
The basic reality of consciousness is a datum in its own right. Science can tell us all sorts of weird and wacky things about the world: that time doesn’t flow, that there are no solid objects, that we’re not really free in the way we think we are. But science can’t tell us that we don’t feel pain or see red. The reality of one’s feelings and experiences is immediately known in such a way that their existence cannot seriously be doubted.
There is a worry that the “Get out of the armchair and into the lab” approach can lead to an oversimplistic conception of what science is, as though science were simply a matter of setting up experiments and then recording the data. In fact, certain crucial scientific developments have involved radically reimagining nature, dreaming up possibilities—perhaps from the comfort of an armchair—that nobody had previously entertained.
Here are just a few of the most important ways in which great scientists have reimagined nature:
Popular myth tells us that Newton was the first person to realize that apples fall to the ground. Of course, he wasn’t. But he was the first person to entertain the idea that what makes apples fall to the ground is the same thing that keeps the moon in orbit around the earth. It had not previously occurred to anyone that a single force might be responsible for both of these phenomena. What now seems to us so natural was at the time an inspired leap of the imagination.
Before the twentieth century, scientists had taken it for granted that space and time are different things. Indeed, time and space do seem to have very different characteristics: time flows from past to future, while space seems to be “all there” at once. It was thus a radical reimagining of nature when Hermann Minkowski, in his mathematical interpretation of Einstein’s special theory of relativity, dispensed with “space” and “time” as distinct entities, and replaced them with a single entity: spacetime. As Minkowski boldly put it, “Henceforth space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality.”5
Just as nobody before Newton had dreamed of identifying the force which pulls apples to the ground with the force which keeps the moon in orbit, so nobody before Einstein had dreamed of identifying gravitational force (the force which pulls apples to the ground and keeps the moon in orbit) with inertial force (the force which pushes you back in your car seat when you accelerate). And that was not all: in Einstein’s baffling reimagining of nature, gravitational force is the result of curvature in the fabric of spacetime. We can only be in awe of the imagination that was able to dream up such a picture of the world!
Of course, all of these novel reimaginings of nature were subsequently tested with observation and experiment in order to work out whether we have any reason to think that they are true. Nonetheless, the point remains that many important moments in scientific progress involved dreaming up new possibilities, conjuring up in the imagination new ways of thinking about the universe. This is overlooked if we have a conception of science that is too focused on experiment and observation. In the years when he was developing special relativity, Einstein wasn’t busy conducting experiments; rather he was staring into space wondering what would happen if you rode on a beam of light.
When we neglect the role of deep thought in science, we close off options. It is quite possible that progress on our scientific understanding of consciousness will be made not only through observation of the brain—important as that is—but also through radically reimagining mind and brain, dreaming up new possibilities not so far entertained by our theories. In chapter 4 of this book, we will explore one proposal for doing precisely this.
There is a further problem with the approach of Seth and the Churchlands. They are assuming not only that consciousness can be explained scientifically, but that it can be explained by the scientific method as we currently envisage it. However, there is good reason to think that explaining consciousness will require a change in our understanding of what science is, a change as fundamental and wide-ranging as that which occurred at the start of the scientific revolution. This is because, as we will discover in the next section, the scientific revolution itself was premised on putting consciousness outside of the domain of scientific inquiry. If we ever want to solve the problem of consciousness, we will need to find a way of putting it back.
While Descartes was the father of modern philosophy, Galileo Galilei (1564–1642) is standardly thought of as the father of modern science. His formulation of the mathematical laws of nature—the precursor of Newton’s (1643–1727) laws of motion and universal gravitation—and his defense of the Copernican view that the earth and planets revolve around the sun—for which he was persecuted by the Church—laid the foundations for the scientific revolution. What is perhaps less remarked upon is that Galileo was also one of the greatest philosophers who ever lived. There are at least two respects in which his contribution to the scientific revolution was a philosophical, rather than a scientific, achievement:
The scientific revolution marked the overturning of the Aristotelian orthodoxy; that is to say, the widespread acceptance of the worldview of the ancient Greek philosopher Aristotle (384–322 BCE). Aristotle’s worldview was complex and multifaceted, but there are two core features in particular that were rejected in the scientific revolution:
Aristotle adhered to the Ptolemaic view of the universe, according to which the earth was in the center of the universe, with the stars and planets orbiting around it.
Aristotle’s theory was teleological: inanimate objects had goals built into them that explained their movement. For example, matter falls to the ground because it aims to get back to its natural home in the center of the universe, while fire rises because its natural home is in the heavens.
It is popularly assumed that Aristotle’s view was shown to be false through the new experimental method, particularly through observing the heavens with the aid of telescopes. Of course, there is a great deal of truth in this. However, it is crucial to note that Galileo managed to reject one crucial plank of Aristotle’s theory of the physical universe not through observation or experiment, but through pure philosophical argument. Galileo proved that Aristotle’s view that heavy objects fall to the ground faster than lighter ones—a doctrine of common sense that had been believed for thousands of years—was logically incoherent. We will discuss Galileo’s argument in more detail in chapter 3.
Moreover, Galileo’s most fundamental reimagining of nature—more fundamental than his embracing of the Copernican model of the universe—was never justified by observation or experiments. It was, and remains, a piece of philosophical speculation. And it is this philosophical speculation—which to this day underlies our scientific picture of the universe—that is to blame for the contemporary problem of consciousness. Let me explain.
One of Galileo’s most significant contributions to the scientific revolution was his radical declaration of 1623 that mathematics is to be the language of science:
Philosophy [by which Galileo meant “natural philosophy,” i.e., what we now call “natural science”] is written in this grand book, the universe, which stands continually open to our gaze, but it cannot be understood unless one first learns to comprehend the language and read the letters in which it is composed. It is written in the language of mathematics, and its characters are triangles, circles, and other geometrical figures, without which it is humanly impossible to understand a single word of it; without these, one wanders about in a dark labyrinth.6
Why had previous thinkers not framed their theories of nature in mathematical language? The problem was that before Galileo philosophers took the world to be full of what philosophers call sensory qualities, things like colors, smells, tastes, and sounds. And it’s hard to see how sensory qualities could be captured in the purely quantitative language of mathematics. How could an equation ever explain to someone what it’s like to see red, or to taste paprika? How could an abstract mathematical description convey the sweet smell of flowers?
But if mathematics cannot capture the sensory qualities of matter—the redness of a tomato, the spiciness of paprika, the smell of flowers—then mathematics will be unable to completely describe nature, for it will miss out on the sensory qualities. This posed a severe challenge for Galileo’s hope that the “book of the universe” might be written in an entirely mathematical language.
Galileo solved this problem with a radical reimagining of the material world. In this reimagining material objects don’t really have sensory qualities. Paprika isn’t really spicy, flowers don’t really smell of anything, objects aren’t really colored. In Galileo’s reimagined world, material objects have only the following characteristics:
Size
Shape
Location
Motion
Hence, for Galileo, the lemon I see in front of me isn’t really yellow, and it doesn’t really have a citrus smell and a sour taste. In reality the lemon is simply a thing which has a certain size, shape, and location. Of course, the lemon has parts, and there will be a great deal of complexity involved in the arrangement of and the relationship between these parts. But all of that complexity can, according to Galileo, be wholly characterized in terms of the sparse characteristics mentioned above: size, shape, location, and movement.
What is so special about the characteristics of size, shape, location, and movement? The crucial point is that these characteristics can be captured in mathematics. Galileo did not believe that you could convey in mathematical language the yellow color or the sour taste of the lemon, but he realized that you could use a geometrical description to convey its size and shape. And it is possible in principle to construct a mathematical model to describe the motion of, and the relationships between, the lemon’s atoms and subatomic parts. Thus, by stripping the world of its sensory qualities (color, smell, taste, sound), and leaving only the minimal characteristics of size, shape, location, and motion, Galileo had—for the first time in history—created a material world which could be entirely described in mathematical language.*1
But what of the sensory qualities? If the yellowness, the citrus smell, and sour taste aren’t really in the lemon, then where are they? Galileo had an answer for this too: the soul.*2 For Galileo, the lemon itself isn’t really yellow; rather yellowness exists in the soul of the person perceiving the lemon. Likewise, neither the sour taste nor the citrus smell are really in the lemon; rather they’re in the soul of the person tasting or smelling the lemon. Just as beauty exists only in the eye of the beholder, so colors, smells, tastes, and sounds exist only in the conscious soul of a human being as she experiences the world. In other words, Galileo transformed the sensory qualities from features of things in the world—such as lemons—into forms of consciousness in the souls of human beings.
Consider the age-old philosophical conundrum, “If a tree falls in a forest, and there’s nobody there to hear it, does it make a sound?” In Galileo’s reimagining of the world, the answer is a clear and resounding no. The falling tree produces vibrations in the air, vibrations which have the mathematical characteristics of size, shape, location, and motion. But it is only when there is a soul around to react to these vibrations that a sound comes into existence. Sound for Galileo is not a feature of the material world, but a form of consciousness existing only in the conscious soul of a human being.
Thus, Galileo’s universe was divided up into two radically different kinds of entity. On the one hand, there are material objects, which have only the mathematical characteristics of size, shape, location, and motion. On the other hand, there are souls enjoying a rich variety of forms of sensory consciousness in response to the world. And the benefit of this picture of the world was that the material world with its minimal characteristics could be entirely captured in the language of mathematics. This was the birth of mathematical physics.
By appreciating this radical division, we can see that Galileo certainly did not take physical science (or “natural philosophy” as he called it) to be a complete account of the world. Physical science, for Galileo, was limited to describing only the material world: its purely quantitative vocabulary meant that it was unable to capture the sensory qualities that reside in the soul. Galileo is the father of physical science, but he only ever intended it to provide us with a partial description of reality.
One might question how much these facts about the origins of physical science bear on the contemporary scientifically informed understanding of the universe. Just because Galileo thought that physical science could not explain the sensory qualities, it doesn’t mean that he was right. Perhaps the scientific method Galileo brought into existence is more powerful than he could ever have imagined.
It is certainly true that Galileo might have been wrong. But these reflections on the origins of physical science do suggest a response to the arguments of Seth and many others that appeal to the incredible track record of science to support the idea that physical science will one day explain consciousness. Physical science has indeed been extraordinarily successful, but we need to bear in mind that its success began when Galileo took the sensory qualities (sounds, smells, tastes, odors) out of its domain of inquiry: by reimagining them as forms of consciousness residing in the incorporeal soul. The fact that physical science has been extremely successful when it ignores the sensory qualities gives us no reason to think that it will be similarly successful if and when it turns its attention to the sensory qualities themselves, this time as forms of consciousness.
Consider the following analogy. A typical academic job (at least in a U.K. university) has three quite different components: teaching, research, and administration. The skills which make one good at research are quite different from the skills that make one good at teaching, which are in turn quite different from the skills that make one good at administration. In my first term as a philosophy lecturer, my head of department was kind enough to simplify the job for me by allowing me to focus only on teaching and research. It turned out that when I focused only on these aspects of the job, I did a pretty good job (even if I do say so myself). But that in itself was no reason to think that when I eventually had to turn my attention to administration I would do just as well. Sadly, I was hopeless.
Analogously, the success of physical science in the last five hundred years is due to the fact that Galileo narrowed its scope of inquiry. Just as my head of department said to me, “Don’t bother for now with administration,” so Galileo said to physical scientists, “Don’t bother for the moment with the sensory qualities.” The argument from “Physical science has been extremely successful” to “Physical science will one day explain the sensory qualities of consciousness” is not supported by the history of science.
Let me repeat for the sake of clarity: I’m not saying that this proves that physical science cannot explain consciousness. But it does undermine arguments that try to show that it inevitably will.
Popular science programs often tell the following story: For thousands of years philosophers tried to work out what reality was like just by sitting around thinking about it, and then one day Galileo came along and said, “I know, let’s find out what the world is like by observing it.” While the development of a new experimental method was crucial, an exclusive focus on this ignores the philosophical underpinnings of our current conception of natural science. Galileo the philosopher created physical science by setting the sensory qualities outside of its domain of inquiry and placing them in the conscious mind. This was a great success, as it allowed what remained to be captured in the quantitative language of mathematics.
However, those sensory qualities have come back to bite us, as we now seek a scientific explanation not only of the inanimate world but also of the conscious mind. And we cannot divorce the subjective inner world of consciousness from the sensory qualities which populate it: the colors, smells, tastes, and sounds that characterize every second of our waking experience. An “explanation” of consciousness that is unable to account for these sensory qualities would in fact be nothing of the sort. If Galileo traveled in time to the present day to hear that we are having difficulty giving a physical explanation of consciousness, he would most likely respond, “Of course you are, I designed physical science to deal with quantities not qualities!”
Physical science is a wonderful thing. And it was only possible because Galileo taught us how to think of matter mathematically. However, Galileo’s philosophy of nature has also bequeathed us deep difficulties. So long as we follow Galileo in thinking (A) that natural science is essentially quantitative and (B) that the qualitative cannot be explained in terms of the quantitative, then consciousness, as an essentially qualitative phenomenon, will be forever locked out of the arena of scientific understanding. Galileo’s error was to commit us to a theory of nature which entailed that consciousness was essentially and inevitably mysterious. In other words, Galileo created the problem of consciousness.
How can we correct this error? In the forthcoming chapters we will consider three possibilities:
Proponents of the first option accept Galileo’s dualism, that is to say, his division of nature into two distinct categories: physical objects with their mathematical properties and incorporeal minds with consciousness. Immaterial minds are normally taken to be beyond scientific understanding. However, the naturalistic dualist denies that the conscious mind is something magical or mysterious, instead taking it to be part of the natural order. Whereas Galileo set the soul outside of the domain of natural science, the naturalistic dualist wants to expand science in such a way as to include nonphysical minds. Naturalistic dualism will be the focus of the next chapter.
Materialists are grateful to Galileo for creating physical science, but respectfully disagree with his conviction that consciousness is a real phenomenon that resists physical explanation. This is the position of Seth and the Churchlands discussed above. Radical materialists argue that consciousness is an illusion. More moderate materialists hope that we will one day be able to explain the subjective inner world of consciousness in terms of the chemistry of the brain. In either case, materialism offers a conservative correction of Galileo’s error, one that does not require a new paradigm of scientific explanation. Materialism will be the subject of chapter 3.
Recent thought about consciousness has been dominated by the above two options. The dualists argue that there can never be a physical explanation of consciousness, while the materialists retort that the soul can never be part of science. It is hard to see how this perennial debate could ever be resolved in favor of one or the other option. But there is a theory which concedes that there is an element of truth in each of these arguments: panpsychism. Panpsychists believe that consciousness is a fundamental and ubiquitous feature of the physical world. An increasing number of philosophers and even some neuroscientists are coming around to the idea that it may be our best hope for solving the problem of consciousness. In chapter 4 I will explain why.
It is too early to say for sure which of these solutions, if any, will solve the problem of consciousness. But you cannot solve a problem unless you have a deep understanding of what exactly the problem is. The problem of consciousness began when Galileo decided that science was not in the business of dealing with consciousness. To solve the problem, we must somehow find a way of making consciousness, once again, the business of science.
*1 Galileo’s attempt to mathematize nature was not without precedent. We find similar moves, for example, in Plato’s Timaeus. However, this was the first time a mathematical theory of nature had achieved widespread acceptance.
*2 In contrast to Descartes, Galileo followed Aristotle in conceiving of the soul as essentially embodied. Nonetheless, it is clear that he took the soul to be incorporeal and outside of the domain of “natural philosophy,” i.e., physical science.