Many books and articles about consciousness appear continually, some with bold titles such as the popular 1991
Consciousness Explained
, by Tufts researcher Daniel Dennett. Using what he calls the “heterophenomenological” method, which treats reports of introspection not as evidence to be used in explaining consciousness, but as data to be explained, he argues that “the mind is a bubbling congeries of unsupervised parallel processing.” Unfortunately, while the brain does indeed appear to work by processing even straightforward jobs such as vision by employing simultaneous multiple pathways, Dennett seems to come to no useful conclusions about the nature of consciousness itself, despite the book’s ambitious title. Near the end of his interminable volume, Dennett concedes almost as an afterthought that conscious experience is a complete mystery. No wonder other researchers have referred to the work as “Consciousness Ignored.”
Dennett joins a long parade of researchers who ignored all the central mysteries of subjective experience and merely addressed the most superficial or easiest-to-tackle aspects of consciousness, those susceptible to the standard methods of cognitive science, which are explainable or potentially explainable with neural mechanisms and brain architecture.
Chalmers, one of the Dennett detractors, himself characterizes the so-called easy problems of consciousness to include “those of explaining the following phenomena:
• the ability to discriminate, categorize, and react to environmental stimuli
• the integration of information by a cognitive system
• the reportability of mental states
• the ability of a system to access its own internal states
• the focus of attention
• the deliberate control of behavior
• the difference between wakefulness and sleep”
In popular literature, some might superficially consider the aforementioned items to represent the totality of the issue. But while
all the above will perhaps eventually be solvable through neurobiology, none represent what biocentrism and many philosophers and neuro-researchers mean by consciousness.
Recognizing this, Chalmers notes the obvious: “The really hard problem of consciousness is the problem of
experience
. When we think and perceive, there is a whir of information-processing, but there is also a
subjective
aspect. This subjective aspect is experience. When we see, for example, we
experience
visual sensations . . . . Then there are bodily sensations, from pains to orgasms; mental images that are conjured up internally; the felt quality of emotion, and the experience of a stream of conscious thought. It is undeniable that some organisms are subjects of experience. But the question of how it is that these systems are subjects of experience is perplexing . . . . It is widely agreed that experience arises from a physical basis, but we have no good explanation of why and how it so arises. Why should physical processing give rise to a rich inner life at all? It seems objectively unreasonable that it should, and yet it does.”
What makes a consciousness problem easy or hard is that the former concern themselves solely with functionality, or the performance aspects, so that scientists need only discover which part of the brain controls which, and they can go away rightfully saying they have solved an area of cognitive function. In other words, the issue is the relatively simple one of finding mechanisms. Conversely, the deeper and infinitely more frustrating aspect of consciousness or experience is hard, as Chalmers points out, “precisely because it is not a problem about the performance of functions. The problem persists even when the performance of all the relevant functions are explained.” How neural information is discriminated, integrated, and reported still doesn’t explain how it is
experienced.
For any object—a machine or a computer—there is commonly no other explanatory or operating principle but physics and the chemistry of the atoms that compose it. We have already started down the long road of building machines with advanced technology and computer memory systems, with electrical microcircuits and solid-state devices that allow the performance of tasks with
increasing precision and flexibility. Perhaps one day we’ll even develop machines that can eat, reproduce, and evolve. But until we can understand the exact circuitry in the brain that establishes the logic of spatial-temporal relationships, we can’t create a conscious machine such as Data in
Star Trek
or David, the boy in
A.I.
My interest in the importance of animal cognition—and how we see the world—led me to Harvard University in the early 1980s to work with psychologist B.F. (Fred) Skinner. The semester glided away pleasantly enough, partly in exchanging opinions with Skinner and partly in experiments in the laboratory. Skinner hadn’t done any research in the laboratory in nearly two decades, when he taught pigeons to dance with each other and even to play Ping-Pong. Our experiments eventually succeeded, and a couple of our papers appeared in
Science
. The newspapers and magazines made a happy use of them with headlines such as “Pigeon Talk: A Triumph for Bird Brains” (
Time
), “Ape-Talk: Two Ways to Skinner Bird” (
Science News
), “Birds Talk to B.F. Skinner” (
Smithsonian
), and “Behavior Scientists ‘Talk’ With Pigeons” (
Sarasota Herald-Tribune
). They were fun experiments, Fred explained on the
Today
show. It was the best semester I had in medical school.
It was also a very auspicious beginning. These experiments correlated well with Skinner’s belief that the self is “a repertoire of behavior appropriate to a given set of contingencies.” However, in the years that have passed, I have come to believe that the questions cannot all be solved by a science of behavior. What is consciousness? Why does it exist? Leaving these unanswered is almost like building and launching a rocket to nowhere—full of noise and real accomplishment, but exposing a vacuum right smack in its
raison d’être
. There is a kind of blasphemy asking these questions, a kind of personal betrayal to the memory of that gentle yet proud old man who took me into his confidence so many years ago. Yet the issues hang in the air, as tangible, if nonverbal, as the dragonfly, or the glowworm, there along the causeway, emitting its greenish light. Or maybe it was the futile attempts of neuroscience to explain consciousness using phenomena such as explicit neuronal representation.
The implication of those early experiments was, of course, that the problem of consciousness might someday be solved once we understand all the synaptic connections in the brain. Yet pessimism always lurked, unspoken. “The tools of neuroscience,” writes Chalmers, “cannot provide a full account of conscious experience, although they have much to offer. [Perhaps] consciousness might be explained by a new kind of theory.” Indeed, in a 1983 National Academy Report, the Research Briefing Panel on Cognitive Science and Artificial Intelligence stated that the questions with which it concerned itself “reflect a single underlying great scientific mystery, on par with understanding the evolution of the universe, the origin of life, or the nature of elementary particles . . .”
The mystery is plain. The neuroscientists have developed theories that might help to explain how separate pieces of information are integrated in the brain, and thus apparently succeed in elucidating how different attributes of a single perceived object—such as the shape, color and smell of a flower—are merged into a coherent whole. For example, some scientists, like Stuart Hameroff, argue that this process occurs so bedrock-deeply that it involves a quantum physical mechanism. Other scientists, like Crick and Koch, believe that the process occurs through the synchronization of cells in the brain. That there is major disagreement about something so basic is sufficient testament to the Niagara of the task that lies ahead, if even we are destined to succeed at grasping the mechanics of consciousness.
As theories, the work of the past quarter-century reflects some of the important progress that is occurring in the fields of neuroscience and psychology. The bad news is that they are solely theories of structure and function. They tell us nothing about how the performance of these functions is accompanied by a conscious experience. And yet the difficulty in understanding consciousness lies precisely here, in this gap, in understanding how a subjective experience emerges from a physical process at all. Even the Nobel Laureate physicist Steven Weinberg concedes that there is a problem with consciousness, and that although it may have a neural correlate,
its existence does not seem to be derivable from physical laws. As Emerson has said, it contradicts all experience:
Here we find ourselves, suddenly, not in a critical speculation, but in a holy place, and should go very warily and reverently. We stand before the secret of the world, there where Being passes into Appearance, and Unity into Variety.
What Weinberg and others who have pondered the issue complain about is that, given all the chemistry and physics we know, given the brain’s neurological structure and complex architecture, and its constant trickle-current, it is nothing short of astonishing that the result is—this! The world in all its manifold sights and smells and emotions. A subjective feeling of
being
, of aliveness, that we all carry so unrelentingly that few give it a moment’s thought. There is no principle of science—in any discipline—that hints or explains how on Earth we get this from that.
Many physicists claim that a “Theory of Everything” is hovering right around the corner. Yet they’ll readily admit they have no idea about how to elucidate what Paul Hoffman, the former publisher of
Encyclopaedia Britannica
, called “the greatest mystery of all”—the existence of consciousness. To whatever small incremental degree its secrets get revealed, however, the discipline that has and will continue to accomplish this is biology. Physics has tried in this area and has decided it is in over its head. It can furnish no answers. The problem for today’s science—as consciousness researchers are continually discovering—is finding hooks or hints, leads to follow, when all roads thus far lead only to neural architecture and what sections of the brain are responsible for what. Knowing which parts of the brain control smell, for example, is not helpful in uncovering the subjective
experience
of smell—
why
a wood fire has its telltale scent. It is, for current science, such an extremely frustrating predicament that few bother taking any first steps. It must feel like the nature of the sun did to the ancient Greeks. Every day a ball of fire
crosses the sky. How would one
begin
to ascertain its composition and nature? What possible steps could one take when the invention and principles of the spectroscope lay two millennia in the future?
“Let man,” declared Emerson, “then learn the revelation of all nature and all thought to his heart; this, namely; that the Highest dwells with him; that the sources of nature are in his own mind.”
If only the physicists had respected the limits of their science as Skinner did his. As the founder of modern behaviorism, Skinner did not attempt to understand the processes occurring within the individual; he had the reserve and prudence to consider the mind a “black box.” Once, in one of our conversations about the nature of the universe, about space and time, Skinner said, “I don’t know how you can think like that. I wouldn’t even know how to begin to think about the nature of space and time.“ His humility revealed his epistemological wisdom. However, I also saw in the softness of his glance the helplessness that the topic occasioned.
Clearly, it is not solely atoms and proteins that hold the answer to the problem of consciousness. When we consider the nerve impulses entering the brain, we realize that they are not woven together automatically, any more than the information is inside a computer. Our thoughts and perceptions have an order, not of themselves, but because the mind generates the spatio-temporal relationships involved in every experience. Even taking cognition to the next step by fabricating a sense of meaning to things necessitates the creation of spatio-temporal relationships, the inner and outer forms of our sensuous intuition. We can never have any experience that does not conform to these relationships, for they are the modes of interpretation and understanding—the mental logic that molds sensations into 3D objects. It would be erroneous, therefore, to conceive of the mind as existing in space and time before this process, as existing in the circuitry of the brain before the understanding posits in it a spatio-temporal order. The situation, as we have seen, is like playing a CD. The CD itself contains only information, yet when the player is turned on, the information leaps into fully dimensional sound. In that way, and in that way only, does the music exist.
Let Emerson’s words suffice, that “the mind is One, and that nature is its correlative.” Indeed, existence itself consists in the logic of this relationship. Consciousness has nothing to do with physical structure or function per se. It is like the stem of the ground pine, there reaching through the earth at a hundred places, drawing its existence from the temporal reality of perceptions in space.
And what of that favorite sci-fi theme, of machines developing minds of their own? “Can we help but wonder,” asked Isaac Asimov, “whether computers and robots may not eventually replace any human ability?“ At Skinner’s eightieth birthday party, I was seated next to one of the world’s leading experts on artificial intelligence. During our conversation, he turned to me and asked, “You’ve worked very closely with Fred. Do you think that we’ll ever be able to duplicate the mind of one of your pigeons?”
“The sensory-motor functions? Yes,” I replied. “But not consciousness. This is an impossibility.”
“I don’t understand.”
But Skinner had just gone up to the podium, and the organizers had asked him to give a little talk. It was Fred’s party after all, and it hardly seemed the proper occasion for one of his former students to go into a diatribe about consciousness. But now, I do not hesitate to say that until we understand the nature of consciousness, a machine can never be made to duplicate the mind of a man, or a pigeon, or even of a dragonfly. For an object—a machine, a computer—there is no other principle but physics. In fact, it is only in the consciousness of the observer that they exist at all in space and time. Unlike a man or a pigeon, they do not have the unitary sense experience necessary for perception and self-awareness, for this must occur before the understanding generates the spatio-temporal relationships involved in every sense experience, before the relationship between consciousness and the spatial world is established.