How do neurobiological processes in the brain cause consciousness? I think this is the most important question in the biological sciences today. Two related questions: Where exactly is consciousness realized in the brain and how does it function causally in our behavior? Antonio Damasio is one of the leading workers in the field of consciousness research, and after having written a number of books on related problems, in Self Comes to Mind he addresses the problem of consciousness directly. He does not claim to have solved it but he believes that he has made advances and pointed in the right direction for a solution.
What exactly is consciousness? There are a number of senses of the word in ordinary speech, but there is one that is most important for philosophy and science: consciousness consists of qualitative, subjective states of feeling or sentience or awareness. These typically begin when we awake from a dreamless sleep and they go on until we fall asleep again or otherwise become unconscious. Dreams are a form of consciousness. Consciousness, in short, is a matter of the qualitative experiences that we have. To understand qualitativeness, think of the difference between drinking beer, listening to music, and thinking about your income tax. Each experience has a distinct quality.
Because of this qualitative character all conscious states are essentially subjective in the sense that they exist only as experienced by a subject—human or animal. The problem of consciousness can now be stated somewhat more precisely: How does the brain produce qualitative subjectivity? How does it get us over the hump from the objective third-person character of neuron firings to the subjective first-person feelings we have when we are conscious?
There is so much confusion surrounding the notions of objectivity and subjectivity that I need to say a word to clarify them. In one sense, the objective/subjective distinction is about claims to knowledge. I call this the epistemic sense. A claim is said to be objective if its truth or falsity can be settled as a matter of fact independently of anybody’s attitudes, feelings, or evaluations; it is subjective if it cannot. For example, the claim that Van Gogh died in France is epistemically objective. But the claim that Van Gogh was a better painter than Gauguin is, as they say, a matter of subjective opinion. It is epistemically subjective.
In another sense, the objective/subjective distinction is about modes of existence. I call this the ontological sense. An entity has an objective ontology if its existence does not depend on being experienced by a human or animal subject; otherwise it is subjective. For example, mountains, molecules, and tectonic plates are ontologically objective. Their existence does not depend on being experienced by anybody. But pains, tickles, and itches only exist when experienced by a human or animal subject. They are ontologically subjective.
I emphasize these two senses of the distinction because a common mistake is to suppose that because science is objective and consciousness is subjective, there cannot be a science of consciousness. Science is indeed epistemically objective, because scientific claims are supposed to be verifiable independently of anybody’s feelings and attitudes. But the ontological subjectivity of the domain of consciousness does not preclude an objective science of that domain. You can have an (epistemically) objective science of an (ontologically) subjective consciousness. Much confusion has been created by the failure to see this point.
So our question is: How does the brain create ontological subjectivity? We know consciousness happens and we know the brain does it. How does it work? How do we approach this problem scientifically? The standard way is to go through three steps. First, try to find the neurobiological correlate of consciousness. A lot of work has been done on this. There is now even a commonly used abbreviation, NCC, for the neuronal correlate of consciousness. Second, try to test if the correlations are in fact causal. Do the neurobiological states cause consciousness? Third, try to formulate a theory. Why do these processes cause consciousness at all, and why do these specific processes cause these specific conscious states? In recent years there has been a sizable number of important research efforts devoted to solving these problems, and I have reviewed several of the relevant books in these pages.1
One depressing feature of this entire research project is that it does not seem to be making much progress. Most efforts to identify the NCC have concentrated on the thalamocortical system, the area including the thalamus and the different layers of the cortex. But the slowness of progress makes one wonder if we are, perhaps, proceeding on the basis of wrong assumptions. Damasio’s book makes a new start in at least two respects. First, he emphasizes other areas of the brain in the production of consciousness, especially the brain stem. Other theorists ignore the brain stem, presumably because it is an evolutionarily primitive part of the brain. They think consciousness is the result of activity in more advanced neuroanatomical features, such as the thalamocortical system. Second, his entire book is built around the theme that the self plays a crucial role in the creation of consciousness.
To summarize Damasio’s argument2 is not an easy task because the book is densely argued and to me at least often unclear. Here is the basic framework: the brain creates an (unconscious) mind. The brain also creates the self. When the self encounters the mind, consciousness results. As with most important theories there is an underlying intuition that drives his theory, though he does not say it explicitly: whenever I have a conscious experience I always experience it as mine. I do not just have a sequence of unrelated neutral qualitative states that could belong to anybody, but I have them as part of a coherent unity that is constitutive of and experienced as myself. So if consciousness is somehow always related to the self, then it seems natural to think that maybe the key to understanding the neurobiology of consciousness is by way of the neurobiology of the self.
The book addresses two problems: (1) How does the brain construct a mind? and (2) How does the brain make the mind conscious? The brain creates a mind by creating images, which are unconscious momentary patterns on sheets of neurons called maps. The images may be either of parts of the body or of things outside the body, but in general, perception is the result of mapping. Damasio says, “The distinctive feature of brains such as the one we own is their uncanny ability to create maps.” Brain maps are not static; they change from moment to moment. The mind is a consequence of the mapping activity of the brain. “Minds emerge,” Damasio writes, “when the activity of small [neuronal] circuits is organized across large networks so as to compose momentary patterns. The patterns represent things and events located outside the brain.” The term “map” applies to all of these patterns, and though they are mental, they are at this stage still totally unconscious, according to Damasio.
Body mapping is the key to the problem of consciousness, because by mapping the body the brain manages to create the critical component of the self. Having made a mind by making maps, the brain makes the mind conscious by creating a self, and when the self encounters the mind, consciousness results. This is the source of Damasio’s title, Self Comes to Mind:
The decisive step in the making of consciousness is not the making of images and creating the basics of the mind. The decisive step is making the images ours, making them belong to their rightful owners…. [Italics in original.]
Damasio’s two crucial notions are consciousness and the self.
(1) Consciousness. In actual practice I think his idea of consciousness is essentially the one stated above. Its essence is qualitative subjectivity. But when Damasio defines it explicitly it comes out a bit differently: it is “a state of mind in which there is knowledge of one’s own existence and of the existence of surroundings” (italics in original). I do not believe this definition is correct. My dog, Gilbert, is plainly conscious, but in what sense does he have knowledge of his own existence? He is certainly aware of his surroundings when he perceives anything. But it is hard to say that when he is dreaming he has knowledge of the existence of his surroundings. It is Damasio’s right to define a word any way he likes, but I think in practice he uses “consciousness,” as I do, to refer to ontologically subjective states such as pains, and does not use it just to describe epistemic states, such as my knowing that I am in Berkeley.
(2) The Self. The self is a much harder notion to define, and I do not find his definitions entirely clear. He says the self is decomposable into three components, the protoself, the core self, and the autobiographical self. Each of these can come in two forms, the “self-as-object” and the “self-as-knower.” But the self-as-object can also operate as knower.
The protoself is constituted by special kinds of mental images of the body produced in body-mapping structures, below the level of the cerebral cortex. The protoself is “an integrated collection of separate neural patterns that map, moment by moment, the most stable aspects of the organism’s physical structure” (italics in original). The first product of the protoself is “primordial feelings.” Whenever you are awake there has to be some form of feeling. The second form of the self, the “core self,” is about action. “The core self unfolds in a sequence of images that describe an object engaging the protoself and modifying that protoself, including its primordial feelings.” These images are now conscious because they have encountered the self. Finally there is the autobiographical self, constituted in large part by memories of facts and events about the self and about its social setting. The protoself and the core self constitute a “material me.” The autobiographical self constitutes a “social me.” Our sense of person and identity is in the autobiographical self.
When we put this all together we get the following result: conscious minds begin when the self comes to mind, when brains add a process involving a person’s sense of self to the mind mix. Specifically, the neurology of consciousness is organized around the brain structures involved in generating three features: wakefulness, mind, and self. Three major anatomical features are the brain stem, the thalamus, and the cerebral cortex. There is no direct alignment between, on the one hand, each of these anatomical features, and, on the other, each component of the mental trio of wakefulness, mind, and self. All three anatomical divisions contribute some aspect of wakefulness, mind, and self. To be fully conscious you have to have three features: (1) to be awake, (2) to have an operational mind, and (3) to have a sense of self as a protagonist of the experience.
1 For my review of Francis Crick, The Astonishing Hypothesis (Touchstone/Simon and Schuster, 1995) and Roger Penrose, Shadows of the Mind (Oxford University Press, 1994), see The New York Review, November 2, 1995; for my review of Gerald M. Edelman, The Remembered Present (Basic Books, 1989) and Bright Air, Brilliant Fire (Basic Books, 1992), Daniel C. Dennett, Consciousness Explained (Back Bay/Little, Brown, 1991), and Israel Rosenfield, The Strange, Familiar and Forgotten (Vintage, 1993), see The New York Review, November 16, 1995; for my review of Christof Koch, The Quest for Consciousness (Roberts and Company, 2004), see The New York Review, January 13, 2005. Several of these are collected in John Searle, The Mystery of Consciousness (New York Review Books, 1997). ↩
2 I am grateful to Damasio for an e-mail exchange about the correct interpretation of his views. ↩
For my review of Francis Crick, The Astonishing Hypothesis (Touchstone/Simon and Schuster, 1995) and Roger Penrose, Shadows of the Mind (Oxford University Press, 1994), see The New York Review, November 2, 1995; for my review of Gerald M. Edelman, The Remembered Present (Basic Books, 1989) and Bright Air, Brilliant Fire (Basic Books, 1992), Daniel C. Dennett, Consciousness Explained (Back Bay/Little, Brown, 1991), and Israel Rosenfield, The Strange, Familiar and Forgotten (Vintage, 1993), see The New York Review, November 16, 1995; for my review of Christof Koch, The Quest for Consciousness (Roberts and Company, 2004), see The New York Review, January 13, 2005. Several of these are collected in John Searle, The Mystery of Consciousness (New York Review Books, 1997). ↩
I am grateful to Damasio for an e-mail exchange about the correct interpretation of his views. ↩