Mind: A Brief Introduction (John R. Searle) / quote 89 of 138
Biological naturalism
Suppose an animal gets a shortage of water in its system. The shortage of water will cause “saline imbalances” in the system, because the ratio of salt to water is excessive in favor of salt. This triggers certain activities in the kidneys. The kidneys secrete rennin, and the rennin synthesizes a substance called angiotensin 2. This substance gets inside the hypothalamus and affects the rate of neuron firings. As far as we know the differential rates of neuron firings cause the animal to feel thirsty. Now, of course, we do not know all of the details and no doubt as we come to understand more, this brief sketch I have given will seem quaint. But that is the sort of explanation of how the existence of conscious feelings of thirst fits into our overall world-view. All forms of consciousness are caused by the behavior of neurons and are realized in the brain system, which is itself composed of neurons. What goes for thirst goes for all forms of our conscious life whatever, from wanting to throw up to wondering how to translate the poems of Stéphane Mallarmé into colloquial English. All conscious states are caused by lower-level neuronal processes in the brain. We have conscious thoughts and feelings; they are caused by neurobiological processes in the brain; and they exist as biological features of the brain system. I believe that this brief account provides the germ of a solution to the “mind-body problem”: I am suspicious of isms, but it is sometimes helpful to have a name, just to distinguish clearly between one view and another. I call my view “biological naturalism,” because it provides a naturalistic solution to the traditional “mind-body problem,” one that emphasizes the biological character of mental states, and avoids both materialism and dualism. I will state biological naturalism about consciousness as a set of four theses: 1. Conscious states, with their subjective, first-person ontology, are real phenomena in the real world. We cannot do an eliminative reduction of consciousness, showing that it is just an illusion. Nor can we reduce consciousness to its neurobiological basis, because such a third-person reduction would leave out the first-person ontology of consciousness. 2. Conscious states are entirely caused by lower level neurobiological processes in the brain. Conscious states are thus causally reducible to neurobiological processes. They have absolutely no life of their own, independent of the neurobiology. Causally speaking, they are not something “over and above” neurobiological processes. 3. Conscious states are realized in the brain as features of the brain system, and thus exist at a level higher than that of neurons and synapses. Individual neurons are not conscious, but portions of the brain system composed of neurons are conscious. 4. Because conscious states are real features of the real world, they function causally. My conscious thirst causes me to drink water for example. I will explain in detail how this works in…