Causal Emergence of the Conscious Field
In Searle’s view, consciousness is a brain system feature. Brain systems are conscious. But how does this work if Searle believes consciousness has an irreducible subjective ontology? Doesn’t this lead to dualism? According to Searle, no. In his biological naturalism, subjective states of consciousness are part of the material world, like all physical phenomena. Conscious states are physically located inside brains and material in nature. However, the subjective ontology cannot be eliminated. Even if we used neuroscience terms for subjective mental states, the subjective ontology would remain because it’s part of the brain system. So how does the brain function in this regard? How can Searle say that consciousness is a causal feature of the brain? The answer is causal emergence. When system features are caused by components lacking those features, the features are said to be causally emergent. Liquidity is one example. No water molecule has the property of liquidity, but many of them form liquid systems. Liquidity is a property of water, and the phenomenon is causally emergent with respect to water molecules.
In the case of the brain, no single neuron is conscious, but consciousness might be caused by systems of neurons within brains. Consciousness could turn out to be causally emergent with respect to neurons.
Mental causation can also be understood at the emergent systems level—whole conscious mental systems can cause things to happen. Suppose I have an intention to raise my arm, which causes me to raise my arm. I experience doing this as part of my (causally emergent) conscious field. All of my intentional capacities are caused by bottom-up causation. Without bottom-up causation, I would have neither consciousness nor intentional states. One could, however, also argue that there is top- down causation involved. The emergent intentional system can act back on the neurons through top-down causation. Let’s consider a metaphor, compliments of Roger Sperry (Sperry 1969), illustrating how there could be room for both bottom-up and top-down causation in the same system. Think of a wheel. On the one hand, the solid shape is an emergent feature of the system of iron atoms.
On the other hand, the wheel determines the course of the atoms as the atoms revolve around the wheel’s axis. Analogously, we can think of mental causation as a feature of systems of neurons acting back on themselves. The result of Searle’s account is a conscious physical system making decisions and acting in the world as a totality. To see the consequences of his view, Searle compares his position with the traditional physical-mental division described by Descartes. It looks something like this.
spatially located not spatially located
spatially extended not extended in space
explainable by physical processes not explainable by physical processes
acts causally on the physical incapable of acting causally on the physical
has mass, charge etc no mass, charge etc
However, on the basis of our discussion, subjectivity, qualitative feel, and inten- tionality are brain system features. They are physical features. Moreover, mental states and processes reside entirely in the brain. They are located and extended there, explicable by physical processes and capable of acting causally on the physical world. Since mental states and processes are physical, they have mass, charge, etc. What we end up with is one category.
subjective, objective qualitative, quantitative intentional, non-intentional spatially located spatially extended explainable by physical processes acts causally on the physical has mass, charge etc
We live in one physical world incorporating consciousness and mental causation.