Another possibility that Chalmers entertains, which is not logically distinct from his notion of dualism, and is often called panprotopsychism, holds that all physical systems are conscious, albeit a human is more conscious than, say, a light switch. I would certainly agree that a human brain has more to be conscious about than a light switch.
My own view, which is perhaps a subschool of panprotopsychism, is that consciousness is an emergent property of a complex physical system. In this view a dog is also conscious but somewhat less than a human. An ant has some level of consciousness, too, but much less that of a dog. The ant colony, on the other hand, could be considered to have a higher level of consciousness than the individual ant; it is certainly more intelligent than a lone ant. By this reckoning, a computer that is successfully emulating the complexity of a human brain would also have the same emergent consciousness as a human.
Another way to conceptualize the concept of consciousness is as a system that has “qualia.” So what are qualia? One definition of the term is “conscious experiences.” That, however, does not take us very far. Consider this thought experiment: A neuroscientist is completely color-blind—not the sort of color-blind in which one mixes up certain shades of, say, green and red (as I do), but rather a condition in which the afflicted individual lives entirely in a black-and-white world. (In a more extreme version of this scenario, she has grown up in a black-and-white world and has never seen any colors. Bottom line, there is no color in her world.) However, she has extensively studied the physics of color—she is aware that the wavelength of red light is 700 nanometers—as well as the neurological processes of a person who can experience colors normally, and thus knows a great deal about how the brain processes color. She knows more about color than most people. If you wanted to help her out and explain what this actual experience of “red” is like, how would you do it?
Perhaps you would read her a section from the poem “Red” by the Nigerian poet Oluseyi Oluseun:
That actually would give her a pretty good idea of some of the associations people have made with red, and may even enable her to hold her own in a conversation about the color. (“Yes, I love the color red, it’s so hot and fiery, so dangerously beautiful…”) If she wanted to, she could probably convince people that she had experienced red, but all the poetry in the world would not actually enable her to have that experience.
Similarly, how would you explain what it feels like to dive into water to someone who has never touched water? We would again be forced to resort to poetry, but there is really no way to impart the experience itself. These experiences are what we refer to as qualia.
Many of the readers of this book have experienced the color red. But how do I know whether your experience of red is not the same experience that I have when I look at blue? We both look at a red object and state assuredly that it is red, but that does not answer the question. I may be experiencing what you experience when you look at blue, but we have both learned to call red things red. We could start swapping poems again, but they would simply reflect the associations that people have made with colors; they do not speak to the actual nature of the qualia. Indeed, congenitally blind people have read a great deal about colors, as such references are replete in literature, and thus they do have some version of an experience of color. How does their experience of red compare with the experience of sighted people? This is really the same question as the one concerning the woman in the black-and-white world. It is remarkable that such common phenomena in our lives are so completely ineffable as to make a simple confirmation, like one that we are experiencing the same qualia, impossible.
Another definition of qualia is the feeling of an experience. However, this definition is no less circular than our attempts at defining consciousness above, as the phrases “feeling,” “having an experience,” and “consciousness” are all synonyms. Consciousness and the closely related question of qualia are a fundamental, perhaps the ultimate, philosophical question (although the issue of identity may be even more important, as I will discuss in the closing section of this chapter).
So with regard to consciousness, what exactly is the question again? It is this: Who or what is conscious? I refer to “mind” in the title of this book rather than “brain” because a mind is a brain that is conscious. We could also say that a mind has free will and identity. The assertion that these issues are philosophical is itself not self-evident. I maintain that these questions can never be fully resolved through science. In other words, there are no falsifiable experiments that we can contemplate that would resolve them, not without making philosophical assumptions. If we were building a consciousness detector, Searle would want it to ascertain that it was squirting biological neurotransmitters. American philosopher Daniel Dennett (born in 1942) would be more flexible on substrate, but might want to determine whether or not the system contained a model of itself and of its own performance. That view comes closer to my own, but at its core is still a philosophical assumption.
Proposals have been regularly presented that purport to be scientific theories linking consciousness to some measurable physical attribute—what Searle refers to as the “mechanism for causing consciousness.” American scientist, philosopher, and anesthesiologist Stuart Hameroff (born in 1947) has written that “cytoskeletal filaments are the roots of consciousness.”2 He is referring to thin threads in every cell (including neurons but not limited to them) called microtubules, which give each cell structural integrity and play a role in cell division. His books and papers on this issue contain detailed descriptions and equations that explain the plausibility that the microtubules play a role in information processing within the cell. But the connection of microtubules to consciousness requires a leap of faith not fundamentally different from the leap of faith implicit in a religious doctrine that describes a supreme being bestowing consciousness (sometimes referred to as a “soul”) to certain (usually human) entities. Some weak evidence is proffered for Hameroff’s view, specifically the observation that the neurological processes that could support this purported cellular computing are stopped during anesthesia. But this is far from compelling substantiation, given that lots of processes are halted during anesthesia. We cannot even say for certain that subjects are not conscious when anesthetized. All we do know is that people do not remember their experiences afterward. Even that is not universal, as some people do remember—accurately—their experience while under anesthesia, including, for example, conversations by their surgeons. Called anesthesia awareness, this phenomenon is estimated to occur about 40,000 times a year in the United States.3 But even setting that aside, consciousness and memory are completely different concepts. As I have discussed extensively, if I think back on my moment-to-moment experiences over the past day, I have had a vast number of sensory impressions yet I remember very few of them. Was I therefore not conscious of what I was seeing and hearing all day? It is actually a good question, and the answer is not so clear.