Searle invites us to contemplate consciousness from our own point of view—to see that experience makes consciousness the phenomenon it is. Take away experience, and there is no consciousness. The challenge is to explain experience as a natural biological phenomenon. Searle argues that materialists (behaviorists, physicalists, and functionalists) leave out experience when pursuing an ontological reduction of the mind to third-person-observable physical matter, functional systems, or overt behavior. The dualist affirms correctly that experience is not reducible in those ways, but cannot articulate how experience fits into the universe. Imagine the following coffee break discussion between a physicalist, a behaviorist, and a functionalist:
Dualist: How was your coffee?
Physicalist: It produced an epinephrine release, and my dopaminergic system is well activated. How was your coffee?
Behaviorist: My breathing is smooth, and my pupils are dilated.
Functionalist: I process information and respond to questions faster.
Dualist: I like the taste of coffee. Moreover, that experience will never reduce to mere neurological, behavioral, or functional states, because experience concerns qualitatively different phenomena.
Functionalist: It is sometimes said that we functionalists cannot account for experi- ence—those subjective experiences you refer to. However, there is a solution. You must accept that experiences don't exist. Consequently, things become easier.
Dualist: Should we redefine consciousness to exclude experience?
Functionalist: Yes, change the connotation. Not all functionalists agree on this. Some claim that functionalism cannot provide a complete theory of the mind. Others hold that experience can be accounted for within a functionalist framework.
Physicalist: If what you mean by experience are ineffable, inner, subjective, mental entities, then I agree. There are no such things. We are not redefining consciousness. The universe is not composed of both physical matter and experience— only matter. Forget about experience. Give me one natural law containing experience, or illustrate to me how experience would be of any significance to what happens in the physical universe in any way.
Functionalist: Some think that experiences could be epiphenomenal. Experiences could exist without having any effect on anything else in the universe. Experiences are just there—like smoke from an old steamer. The smoke is epiphenomenal to the movement of the ship.
Behaviorist: Superstition—that is what it is. It’s like believing in ghosts or souls. We behaviorists have no use for them!
Physicalist: Experiences are epiphenomenal? I just have two words: Occam’s razor! Why add something that lacks explanatory power? Get rid of experiences until they become part of physics.
If the third-person description was what mattered for the taste of coffee, then what the materialists say would make sense. However, what matters to us when we enjoy coffee is not third-person descriptions of neurological, behavioral, or functional states. The dualist is partly right: what matters is experience, which has an irreducible subjective ontology, but it is not part of dualist ontology. Here the materialist view is compelling—reality is entirely physical. How can we acknowledge the truths of materialism and dualism in our account of the mind? How can we have an account of consciousness true to our scientific conception of the universe and our conscious life with subjective experiences like the taste of coffee? What are we to make of the apparent explanatory gap between matter and consciousness? If we assume that the mental is physical, then it is unclear why there should be a gap. One reason why it might seem as if there should be a gap is confusion as to the relevant causation. The most commonly discussed form of causation is event causation. An example of event causation is when a rolling ball collides with another ball. The impact causes one ball to stop and the other to move.
Event causation is about a series of steps. First, this happens, and then that, and so on: I flick a switch—the light comes on; two billiard balls collide—one stays put, the other moves, etc. In Searle’s view, however, consciousness—being a brain pro- cess—is not a matter of event causation. There are not two things—the brain and consciousness. There is one conscious brain. The form of causation is closer to how bodies attract each other. Our planet dances around the sun in a gravitational field. But the dance is not caused by separate events—let us say, planet events and gravity events. No, the gravity field is part of a planetary system. Similarly, our consciousness is part of the brain as a system.
Searle calls his view biological naturalism (Searle 1992, p. 18). Consciousness is a natural biological phenomenon like digestion or photosynthesis. The proposed solution can be summarized in one statement: consciousness is caused by and realized in the brain as a system feature. Consciousness depends on specific physical processes, as do other biological phenomena. Photosynthesis is carried out through mechanisms converting water and carbon dioxide into sugar and oxygen. It would be unreasonable to try to cleverly combine liquid nitrogen and uranium to achieve photosynthesis. Photosynthesis is done differently by plants and bacteria, and perhaps we will discover other ways in the future. But some physical processes with the right causal powers must cause the production of sugar and oxygen from water and carbon dioxide. We can say something similar about consciousness. As with photosynthesis, different physical processes could likely cause consciousness. We know that at least some animals are conscious, and there is no reason to think it would be impossible to build some future system X that would be conscious as well.
The answer to the question of how the brain causes consciousness should be articulated in terms of biological structures with adequate causal powers. It is unclear what those structures are and at what level they can be found. Should we understand the causal basis of consciousness in terms of neurons, neural nets, or larger-scale structures? Should we perhaps examine subcellular structures? These questions concern the level of causality. We don’t know the correct level. Moreover, there are questions about the basic nature of the phenomenon—definitional questions. Should we think of consciousness as being piecemeal or as being a field? Research on neural correlates of consciousness has often focused on the first possibility in its search for neural correlates of isolated experiences, such as a visual percept (as was noted in the section “Neural Correlates of Consciousness” earlier in this chapter). This approach is called the building block theory of consciousness. However, why should we think that consciousness comes in fragments? We might be more or less conscious at different times—consciousness allows for different degrees, but as long as we are conscious, it’s a remarkably stable phenomenon, not flickering depending on what we see, hear, think, feel, or otherwise experience. It’s a temporally extended field that comes on gradually as we wake up, and it fades as we go to sleep. The conscious field is neither a container of mental contents nor their sum. Thoughts, percepts, and experiences are integral to the field and exist as its deformations. They are like mountains and valleys in the landscape of consciousness. If the field theory of consciousness is correct, searching for fragments of consciousness and their correlates is misguided..