In order to do science, we’ve had to dismiss the mind. This was, in any case, the bargain that was made in the seventeenth century, when Descartes and Galileo deemed consciousness a subjective phenomenon unfit for empirical study. If the world was to be reducible to physical causation, then all mental experiences—intention, agency, purpose, meaning—must be secondary qualities, inexplicable within the framework of materialism. And so the world was divided in two: mind and matter. This dualistic solution helped to pave the way for the Enlightenment and the technological and scientific advances of the coming centuries. But an uneasiness has always hovered over the bargain, a suspicion that the problem was less solved than shelved. At the beginning of the eighteenth century, Leibniz struggled to accept that perception could be explained through mechanical causes—he proposed that if there were a machine that could produce thought and feeling, and if it were large enough that a person could walk inside of it, as he could walk inside a mill, the observer would find nothing but inert gears and levers. “He would find only pieces working upon one another, but never would he find anything to explain Perception,” he wrote.
Today we tend to regard the mind not as a mill but as a computer, but, otherwise, the problem exists in much the same way that Leibniz formulated it three hundred years ago. In 1995, David Chalmers, a shaggy-haired Australian philosopher who has been called a “rock star” of the field, famously dubbed consciousness “the hard problem,” as a way of distinguishing it from comparatively “easy” problems, such as how the brain integrates information, focusses attention, and stores memories. Neuroscientists have made significant progress on the easier problems, using fMRIs and other devices. Engineers, meanwhile, have created impressive simulations of the brain in artificial neural networks—though the abilities of these machines have only made the difference between intelligence and consciousness more stark. Artificial intelligence can now beat us in chess and Go; it can predict the onset of cancer as well as human oncologists and recognize financial fraud more accurately than professional auditors. But, if intelligence and reason can be performed without subjective awareness, then what is responsible for consciousness? Answering this question, Chalmers argued, was not simply a matter of locating a process in the brain that is responsible for producing consciousness or correlated with it. Such a discovery still would fail to explain why such correlations exist or why they lead to one kind of experience rather than another—or to nothing at all.
One line of reductionist thinking insists that the hard problem is not really so hard—or that it is, perhaps, simply unnecessary. In his new book, “Rethinking Consciousness: A Scientific Theory of Subjective Experience,” the neuroscientist and psychologist Michael Graziano writes that consciousness is simply a mental illusion, a simplified interface that humans evolved as a survival strategy in order to model the processes of the brain. He calls this the “attention schema.” According to Graziano’s theory, the attention schema is an attribute of the brain that allows us to monitor mental activity—tracking where our focus is directed and helping us predict where it might be drawn in the future—much the way that other mental models oversee, for instance, the position of our arms and legs in space. Because the attention schema streamlines the complex noise of calculations and electrochemical signals of our brains into a caricature of mental activity, we falsely believe that our minds are amorphous and nonphysical. The body schema can delude a woman who has lost an arm into thinking that it’s still there, and Graziano argues that the “mind” is like a phantom limb: “One is the ghost in the body and the other is the ghost in the head.”
I suspect that most people would find this proposition alarming. On the other hand, many of us already, on some level, distrust the reality of our own minds. The recent vogue for “mindfulness” implies that we are passive observers of an essentially mechanistic existence—that consciousness can only be summoned fleetingly, through great effort. Plagued by a midday funk, we are often quicker to attribute it to bad gut flora or having consumed gluten than to the theatre of beliefs and ideas.
And what, really, are the alternatives for someone who wants to explain consciousness in strictly physical terms? Another option, perhaps the only other option, is to conclude that mind is one with the material world—that everything, in other words, is conscious. This may sound like New Age bunk, but a version of this concept, called integrated information theory, or I.I.T., is widely considered one of the field’s most promising theories in recent years. One of its pioneers, the neuroscientist Christof Koch, has a new book, “The Feeling of Life Itself: Why Consciousness Is Widespread but Can’t Be Computed,” in which he argues that consciousness is not unique to humans but exists throughout the animal kingdom and the insect world, and even at the microphysical level. Koch, an outspoken vegetarian, has long argued that animals share consciousness with humans; this new book extends consciousness further down the chain of being. Central to I.I.T. is the notion that consciousness is not an either/or state but a continuum—some “systems,” in other words, are more conscious than others. Koch proposes that all sorts of things we have long thought of as inert might have “a tiny glow of experience,” including honeybees, jellyfish, and cerebral organoids grown from stem cells. Even atoms and quarks may be forms of “enminded matter.”
Another term for this is panpsychism—the belief that consciousness is ubiquitous in nature. In the final chapters of the book, Koch commits himself to this philosophy, claiming his place among a lineage of thinkers—including Leibniz, William James, and Alfred North Whitehead—who similarly believed that matter and soul were one substance. This solution avoids the ungainliness of dualism: panpsychism, Koch argues, “elegantly eliminates the need to explain how the mental emerges out of the physical and vice versa. Both coexist.” One might feel that aesthetic considerations, such as elegance, do not necessarily make for good science; more concerning, perhaps, is the fact that Koch, at times, appears motivated by something even more elemental—a longing to reënchant the world. In the book’s last chapter, he confesses to finding spiritual sustenance in the possibility that humans are not the lone form of consciousness in an otherwise dead cosmos. “I now know that I live in a universe in which the inner light of experience is far, far more widespread than assumed within standard Western canon,” he writes. Koch admits that when he speaks publicly on these ideas, he often gets “you’ve-got-to-be-kidding-stares.”
It is an irony of materialist theories that such efforts to sidestep ghostly or supernatural accounts of the mind often veer into surreal, metaphysical territory. Graziano, in a similarly transcendent passage in his book, proposes that the attention-schema theory allows for the possibility of uploading one’s mind to a computer and living, digitally, forever; in the future, brain scans will digitally simulate the individual patterns and synapses of a person’s brain, which Graziano believes will amount to subjective awareness. Like Koch, Graziano, when entertaining such seemingly fanciful ideas, shifts into a mode that oddly mixes lyricism and technical rigor. “The mind is a trillion-stranded sculpture made of information, constantly changing and beautifully complicated,” he writes. “But nothing in it is so mysterious that it can’t in principle be copied to a different information-processing device, like a file copied from one computer to another.”
The strangeness of all this does not mean that such speculations are invalid, or that they undermine the theories themselves. While reading Koch and Graziano, I recalled that the philosopher Eric Schwitzgebel, in 2013, coined the term “crazyism” to describe the postulate that any theory of consciousness, even if correct, will inevitably strike us as completely insane.
If the current science of consciousness frequently strikes us as counterintuitive, if not outright crazy, it’s because even the most promising theories often fail to account for how we actually experience our interior lives. “The result,” Tim Parks writes in his new book, “Out of My Head: On the Trail of Consciousness,” “is that we regularly find ourselves signing up to explanations of reality that seem a million miles from our experience.” In 2015, Parks, a British novelist and essayist, participated in a project funded by the German Federal Cultural Foundation which put writers in conversation with scientists. The initiative led Parks to meet with a number of neuroscientists and observe their research on consciousness. Parks finds that most of the reigning theories upend his intuitive understanding of his own mind. Truth, these experts tell him, lies not in our fallible senses but in the bewildering decrees of science. Our minds, after all, are unreliable gauges of the objective world.
Parks takes a different approach: mental experience lies at the core of “Out of My Head,” not only as subject but as method. For Parks, our subjective understanding of our minds is trustworthy, at least to a degree; he admonishes the reader to weigh every scientific theory against their knowledge of “what it’s really like being alive.” Throughout his account of his travels, he dramatizes his inner life: he notices how time seems to slow down at certain moments and accelerate at others, and how the world disappears entirely when he practices meditation; he describes his fears about his girlfriend’s health and his doubts about whether he can write the book that we are reading.
Most of the neuroscientists whom Parks meets believe that consciousness can be reduced to neuronal activity, but Parks begins to doubt this consensus view. As a novelist, attentive to the nuances of language, he notices that these theories rely a great deal on metaphor: the literature of consciousness often refers to the brain as a “computer,” chemical activity as “information,” and neuronal firing as “computation.” Parks finds it “puzzling that our brains are made up of things—computers—that we ourselves only recently invented.” He asks one neuroscientist how electrical impulses amount to information, and she insists that this is just figurative language, understood as such by everyone in the field. But Parks is unconvinced: these metaphors entail certain theoretical assumptions—that, for instance, consciousness is produced by, or is dependent upon, the brain, like software running on hardware. How are these metaphors coloring the parameters of the debate, and what other hypotheses do they prevent us from considering?
Parks’s skepticism stems in part from his friendship with an Italian neuroscientist named Riccardo Manzotti, with whom he has been having, as he puts it, “one of the most intense and extended conversations of my life.” Manzotti, who has become famous for appearing in panels and lecture halls with his favorite prop, an apple, counts himself among the “externalists,” a group of thinkers that includes David Chalmers and the English philosopher and neuroscientist Andy Clark. The externalists believe that consciousness does not exist solely in the brain or in the nervous system but depends, to various degrees, on objects outside the body—such as an apple. According to Manzotti’s version of externalism, spread-mind theory, which Parks is rather taken with, consciousness resides in the interaction between the body of the perceiver and what that perceiver is perceiving: when we look at an apple, we do not merely experience a representation of the apple inside our mind; we are, in some sense, identical with the apple. As Parks puts it, “Simply, the world is what you see. That is conscious experience.” Like Koch’s panpsychism, spread-mind theory attempts to recuperate the centrality of consciousness within the restrictions of materialism. Manzotti contends that we got off to a bad start, scientifically, back in the seventeenth century, when all mental phenomena were relegated to the subjective realm. This introduced the false dichotomy of subject and object and imagined humans as the sole perceiving agents in a universe of inert matter.
Manzotti’s brand of externalism is still a minority position in the world of consciousness studies. But there is a faction of contemporary thinkers who go even further—who argue that, if we wish to truly understand the mind, materialism must be discarded altogether. The philosopher Thomas Nagel has proposed that the mind is not an inexplicable accident of evolution but a basic aspect of nature. Such theories are bolstered, in part, by quantum physics, which has shown that perception does in some cases appear to have real causal power. Particles have no properties independent of how you measure them—in other words, they require a conscious observer. The cognitive scientist Donald Hoffman believes that these experimental observations prove that consciousness is fundamental to reality. In his recent book “The Case Against Reality: Why Evolution Hid the Truth from Our Eyes,” he argues that we must restart science on an entirely different footing, beginning with the brute fact that our minds exist, and determining, from there, what we can recover from evolutionary theory, quantum physics, and the rest. Theories such as Hoffman’s amount to a return of idealism—the notion that physical reality cannot be strictly separated from the mind—a philosophy that has been out of fashion since the rise of analytic philosophy, in the early twentieth century. But if idealism keeps resurfacing in Western thought, it may be because we find Descartes and Galileo’s original dismissal of the mind deeply unsatisfying. Consciousness, after all, is the sole apparatus that connects us to the external world—the only way we know anything about what we have agreed to call “reality.”
A few years before Parks embarked on his neuro-philosophical tour, he and his wife divorced, and many of his friends insisted that he was having a midlife crisis. This led him to doubt the reality of his own intuitions. “It seems to me that these various life events might have predisposed me to be interested in a theory of consciousness and perception that tends to give credit to the senses, or rather to experience,” he writes.
By the end of the book, it’s difficult to see how spread mind offers a more intuitive understanding of reality than other theories do. In fact, Parks himself frequently struggles to accept the implications of Manzotti’s ideas, particularly the notion that there is no objective world uncolored by consciousness. But perhaps the virtue of a book like Parks’s is that it raises a meta-question that often goes unacknowledged in these debates: What leads us, as conscious agents, to prefer certain theories over others? Just as Parks was drawn to spread mind for personal reasons, he invites us to consider the human motivations that undergird consensus views. Does the mind-as-computer metaphor appeal to us because it allows for the possibility of mind-uploading, fulfilling an ancient, religious desire for transcendence and eternal life? Is the turn toward panpsychism a kind of neo-Romanticism born of our yearning to reënchant the world that materialism has rendered mute? If nothing else, these new and sometimes baffling theories of consciousness suggest that science, so long as it is performed by human subjects, will bear the fingerprints of our needs, our longings, and our hopes—false or otherwise.