Several definitions of consciousness exist, but Annaka Harris cites Thomas Nagel's: "An organism is conscious if it has some sense of what it is like to be that organism." Consciousness is thus experience; if an experience is present, then consciousness exists.
The elusive question of consciousness presents one of the greatest mysteries of our time by asking how something could appear out of nothing, or as Harris phrases, "how does felt experience arise out of non-sentient matter?" According to philosopher David Chalmers, this line of inquiry is the 'hard problem' of consciousness, whereas determining which processes in the brain are responsible for which functions is the 'easy problem.'
The binding problem is one of the most famous hypotheses in neuroscience, stating that our brains bind information to create a cohesive perceptual experience. Our nervous systems receive sensory information from the world at different rates, but our brains synchronize these signals to form our perception of the world.
While consciousness continues to create our experience, consciousness itself cannot be an illusion since it is the only thing we know for sure exists. Illusions can occur within consciousness, but either we are experiencing something, or we aren't. For an illusion to exist, we must be conscious.
Note: The following are excerpts from Conscious: A Brief Guide to the Fundamental Mystery of the Mind by Annaka Harris.
Before posing any questions about consciousness, we must determine what we are talking about in the first place. People use the word in a variety of ways; for example, in referring to a state of wakefulness, a sense of selfhood, or the capacity for self-reflection. But when we want to single out the mysterious quality at the heart of consciousness, it’s important to narrow in on what makes it unique. The most basic definition of consciousness is that given by the philosopher Thomas Nagel in his famous essay “What Is It Like to Be a Bat?,” and it is how I use the word throughout this book. The essence of Nagel’s explanation runs as follows:
An organism is conscious if there is something that it is like to be that organism.
In other words, consciousness is what we’re referring to when we talk about experience in its most basic form. Is it like something to be you in this moment? Presumably your answer is yes. Is it like something to be the chair you’re sitting on? Your answer will (most likely) be an equally definitive no. It’s this simple difference—whether there is an experience present or not—which we can all use as a reference point, that constitutes what I mean by the word “consciousness.” Is it like something to be a grain of sand, a bacterium, an oak tree, a worm, an ant, a mouse, a dog? At some point along the spectrum the answer is yes, and the great mystery lies in why the “lights turn on” for some collections of matter in the universe.
What might qualify as evidence of consciousness? For the most part, we believe we can determine whether or not an organism is conscious by examining its behavior. Here is a simple assumption most of us make, in line with our intuitions, that we can use as a starting point: “People are conscious; plants are not conscious.” Most of us feel strongly that this statement is correct, and there are good scientific reasons for believing that it is. We assume that consciousness does not exist in the absence of a brain or a central nervous system. But what evidence or behavior can we observe to support this claim about the relative experience of human beings and plants? Consider the types of behavior we usually attribute to conscious life, such as reacting to physical harm or caring for others. Research reveals that plants do both of these things in complex ways—though, of course, we conclude that they do so without feeling pain or love (i.e., without consciousness). But some behaviors of people and plants are so alike that this in fact poses a challenge to our using certain behavior as evidence of conscious experience.
In theory, I could act in all the ways I do and say all the things I say without having a conscious experience of it, much as an advanced robot might (though, admittedly, it’s hard to imagine). This is the gist of a thought experiment referred to as the “Philosophical Zombie,” which was made popular by David Chalmers. Chalmers asks us to imagine that any person could, in effect, be a zombie—someone who looks and acts exactly like everyone else on the outside without experiencing anything at all on the inside. The zombie thought experiment is controversial, and other philosophers, notably Daniel Dennett of Tufts University, claim that what it proposes is impossible—that a fully functioning human brain must be conscious, by definition. But the conceivability of a “zombie” is worth contemplating if only in theory, because it helps us pin down which behaviors, if any, we think must be accompanied by consciousness.
In other words, when we trick ourselves into imagining that people lack consciousness, we can begin to wonder if we’re in fact tricking ourselves all the time when we deem other living systems—climbing ivy, say, or stinging sea anemones—to be without it. We have a deeply ingrained intuition, and therefore a strongly held belief, that systems that act like us are conscious, and those that don’t are not. But what the zombie thought experiment makes vivid to me is that the conclusion we draw from this intuition has no real foundation. Like a 3-D image, it collapses the moment we take our glasses off.
The “split-brain” phenomenon is also informative here, shedding light on both the malleability of consciousness and the concept of the self. Many people are now aware of the fascinating research conducted by Roger Sperry and Michael Gazzaniga at Caltech, beginning in the 1960s, on epilepsy patients who had undergone a corpus callosotomy. This is a surgical procedure in which the corpus callosum is cut, either partially or fully, separating connections between the left and right hemispheres of the brain in an effort to prevent seizures from spreading. Although these split-brain patients appeared surprisingly unchanged by the procedure, research on them revealed a bizarre and counterintuitive reality that calls into question many of our assumptions about the fluidity and boundaries of consciousness.
In experiments on people who have undergone split-brain surgery, information can be given separately to each of their two brain hemispheres through vision (in the form of pictures, written language, etc.), because the right visual field is projected to the left hemisphere of the brain and vice versa. In a normal person, the information coming through either visual field is shared with the opposite hemisphere of the brain through the corpus callosum. In split-brain patients, visual stimulus to each field is received by only one side of the brain. The same goes for stimuli presented to each ear, as well as for most of the information from patients’ hands—for the most part, the touch receptors from each hand project to the opposite hemisphere of the brain, and the movement of each hand is also controlled by the opposite hemisphere. In fact, after surgery, split-brain patients can experience something called “hemispheric rivalry,” in which they are seen attempting opposing behaviors with their left and right hands in a disconcerting battle—such as trying to button up their shirt with one hand while the other hand is busy at work unbuttoning; attempting to hug a spouse with one arm while pushing him away with the other; and simultaneously opening and closing a door with opposite hands.
The split-brain literature contains many examples suggesting that two conscious points of view can reside in a single brain. Most of them also topple the typical notion of free will, by exposing a phenomenon generated by the left hemisphere that Gazzaniga and his colleague Joseph LeDoux dubbed “the interpreter.” This phenomenon occurs when the right hemisphere takes action based on information it has access to that the left hemisphere doesn’t, and the left hemisphere then gives an instantaneous and false explanation for the split-brain subject’s behavior. For example, when the right hemisphere is given the instruction “Take a walk” in an experiment, the subject will stand up and begin walking. But when asked why he’s leaving the room, he will give an explanation such as, “Oh, I need to get a drink.” His left hemisphere, the one responsible for speech, is unaware of the command the right side received, and we have every reason to think that he does in fact believe his thirst was the reason he got up and began walking. As in the example in which experimenters were able to cause a feeling of will in subjects who in actuality were not in control of their own actions, the phenomenon of “the interpreter” is further confirmation that the feeling we have of executing consciously willed actions, at least in some instances, is sheer illusion.
The term Panpsychism, coined by the Italian philosopher Francesco Patrizi in the sixteenth century, is derived from the Greek pan (“all”) and psyche (“mind” or “spirit”). Some versions of panpsychism describe consciousness as separate from matter and composed of some other substance, a definition reminiscent of vitalism and traditional religious descriptions of a soul. But while the term has been used to describe a wide range of thinking throughout history, contemporary considerations of panpsychism provide descriptions of reality very different from the earlier versions—and are unencumbered by any religious beliefs. One branch of modern panpsychism proposes that consciousness is intrinsic to all forms of information processing, even inanimate forms such as technological devices; another goes so far as to suggest that consciousness stands alongside the other fundamental forces and fields that physics has revealed to us—like gravity, electromagnetism, and the strong and weak nuclear forces. The full range of serious deliberations regarding panpsychism—whether they narrow in on certain types of information processing or apply to all matter universally—are unlike most of the panpsychic theories of the past. Modern thinking about panpsychism is informed by the sciences and is fully aligned with physicalism and scientific reasoning.
Some philosophers go so far as to suggest that there isn’t a hard problem of consciousness at all, reducing consciousness to an illusion. But as others have 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. In his essay “The Consciousness Deniers,” the British analytic philosopher Galen Strawson analyzes this view of consciousness-as-illusion and expresses exasperation with the utter incoherence of the idea: “How could anybody have been led to something so silly as to deny the existence of conscious experience, the only general thing we know for certain exists?” The philosopher Ned Block, of NYU’s Center for Neural Science, describes something he’s observed in his students akin to different personality types when he lectures about the hard problem of consciousness. He estimates that about one-third of his students “don’t appreciate phenomenology [felt experience] and the difficult problems it raises,” and he thinks it would be interesting to study the neurological difference between people who are able to intuitively grasp the hard problem and those who aren’t (or who view it as an illusion). Regardless, relegating consciousness to the status of an illusion misses the point, in my view. In effect, it is simply redefining consciousness as “the illusion of consciousness.” Even if we agreed to call consciousness an illusion, which seems absurd, we would still wonder how deep this illusion goes. Are other complex processes, or other collections of matter, experiencing this “illusion”? All the questions of consciousness and panpsychism would still stand before us.
As we go about our daily lives, we experience what appears to be a continuous stream of present-moment events, yet we actually become conscious of physical events in the world slightly after they have occurred. In fact, one of the most startling findings in neuroscience has been that consciousness is often “the last to know.” Visual, auditory, and other kinds of sensory information move through the world (and our nervous system) at different rates. The light waves and sound waves emitted the moment the tennis ball makes contact with your racket, for example, do not arrive at your eyes and ears at the same time, and the impact felt by your hand holding the racket occurs at yet another interval. To complicate matters further, the signals perceived by your hands, eyes, and ears travel different distances through your nervous system to reach your brain (your hands are a lot farther away from your brain than your ears are). Only after all the relevant input has been received by the brain do the signals get synchronized and enter your conscious experience through a process called “binding”—whereby you see, hear, and feel the ball hit the racket all in the same instant. As the neuroscientist David Eagleman puts it:
"Your perception of reality is the end result of fancy editing tricks: the brain hides the difference in arrival times. How? What it serves up as reality is actually a delayed version. Your brain collects up all the information from the senses before it decides upon a story of what happens. . . . The strange consequence of all this is that you live in the past. By the time you think the moment occurs, it’s already long gone. To synchronize the incoming information from the senses, the cost is that our conscious awareness lags behind the physical world."
In fact, we know that the human brain, under the right conditions, can seamlessly integrate foreign objects into its map of what constitutes its body. The rubber-hand illusion is an example of how, when certain conditions are met, an outside object can become included in one’s conception of self. In the original experiment, the subject sits with his real hand underneath a table, while a rubber hand rests on the table in its place. When the experimenter strokes the subject’s real hand and the rubber hand simultaneously with a brush, the subject begins to feel that the rubber hand he sees on the table belongs to him. Later versions of the rubber-hand illusion have been demonstrated with the use of virtual reality. In one of these experiments, conducted by the neuroscientist Anil Seth and his team at the University of Sussex, the subject wears virtual reality goggles and experiences a virtual world in which she has a virtual hand. Sometimes the experimenters cause the hand to flash red in sync with the subject’s heartbeat and sometimes it is out of sync. As we would expect, the subject has a greater feeling of ownership of the virtual hand when the flashing is in sync with her heartbeat. Seth refers to our experiences of ourselves in the world as a kind of “controlled hallucination.” He describes the brain as a “prediction engine” and explains that “what we perceive is its best guess of what’s out there in the world.” In a sense, he says, “we predict ourselves into existence.”
Is it possible to simply be aware of events, actions, feelings, thoughts, and sounds—all coming in a stream of awareness? Such an experience is not uncommon in meditation, and many people, myself included, can attest to it. The self we seem to inhabit most (if not all) of the time—a localized, unchanging, solid center of consciousness—is an illusion that can be short-circuited, without changing our experience of the world in any other way. We can have a full awareness of the usual sights, sounds, feelings, and thoughts, absent the sense of being a self who is the receiver of the sounds and the thinker of the thoughts. This is not at all at odds with modern neuroscience: an area of the brain known as the default mode network, which scientists believe contributes to our sense of self, has been found to be suppressed during meditation.
The typical notion of “self,” along with other misperceptions of everyday experiences, can be overcome through meditation training, which is also now better understood at the level of the brain. For thousands of years, Eastern contemplative traditions have used meditation as an experimental basis for studying the nature of consciousness, and although Western science is a relative latecomer to these methods of introspection, research is now being conducted by neuroscientists on the specific effects of meditation on the mind and brain. This research will hopefully lead to new discoveries about how training our attention in systematic ways can provide a better understanding of consciousness and human psychology. At the very least, it confirms that valuable insights can be had through first-person tools of investigation. The Buddhist scholar Andrew Olendzki describes the illusory nature of self that can be revealed through meditation: Like the flatness of the earth or the solidity of the table, it [the notion of self] has utility at a certain level of scale—socially, linguistically, legally—but thoroughly breaks down when examined with closer scrutiny.