Henry Stapp believes that classical physics cannot describe the brain, and thinks that a quantum framework is needed for a full explanation. He is sympathetic to the pre-quantum age ideas of William James, who suggested that consciousness was a ‘selecting agent’ present when choices have to be made.
Stapp bases his theory of consciousness on Heisenberg’s interpretation of quantum theory. The Copenhagen interpretation was the first quantum orthodoxy promulgated by Neils Bohr. This was pragmatic in recommending quantum mechanics as a system of rules that allowed the calculation of empirically verifiable relationships between observations.
Heisenberg refined this position. Bohr and Heisenberg agreed in viewing the theory as a set of rules for making predictions about observations made under experimental conditions. However, Heisenberg thought that the theory was something more than a system of statistical rules, and that the probability distribution of quantum theory really existed in nature. He considered that the evolution of this probability distribution was punctuated by uncontrolled quantum wave collapses, which are the events that actually occur in nature, and the manifestation of which eliminates the other possibilities in the probability distribution.
The emphasis is thus on the probability distribution. Heisenberg did not view the quanta as actual things, but as tendencies for certain types of events to occur. The orderly evolution of the quantum system is deterministic, but this controls only the tendency for things or propensity for events and not the actual things or events themselves. The things or events are controlled by quantum jumps that do not individually conform to any natural law, but collectively conform to statistical rules.
With respect to the brain and consciousness, Stapp considers that some brain processes such as the calcium ions that are involved in the release of neurotransmitters at synapses need to be treated quantum mechanically. Further, he thinks that the non-linearity of the synaptic system and the large number of metastable states into which the brain can evolve point to a quantum mechanical structure.
Although Stapp thinks there is quantum based activity in the synapses and possibly other aspects of the brain, his theory, in contrast to quantum brain dynamics or Orch OR, is not really based at the microscopic level. Instead, Stapp envisages consciousness as exercising top-level control over neural excitation in the brain. Quantum brain events are suggested to occur at the whole brain level rather than the level of the synapses.
In this system, conscious events are selected from the large-scale excitation of the brain. He speaks of a creative event bringing into being one of a range of possibilities that exist in Heisenberg’s quantum distribution of probabilities. The neural excitations are a code, and each experience is regarded as a selection from this code. The conscious brain is seen as a system that is internally determined in a way that cannot be represented outside the system, whereas in the rest of the physical universe an external representation of an object or system and knowledge of the laws of physics allow accurate predictions as to future events.
Stapp views the brain as a self-programming computer with self-sustaining input from memory, which is a code derived from previous experience. This results in a number of probabilities from which consciousness has to select. The conscious act is a selection of a piece of top-level code, which then exercises control over the flow of neural excitation. Each human experience is accompanied by the activation of a top-level code.
Evidence for Stapp’s Model
Stapp says that proof of his theory requires the identification of the neurons that provide the top-level code and also the mechanism by which the memory store is turned into further top-level code. The conscious events are seen as being capable of grasping a whole pattern of activity, and this in turn is seen as accounting for the unity of our consciousness.
Stapp envisages a top level of brain processing involved with information gathering, planning of actions, choice of particular plans and execution and monitoring of these plans. It is suggested that each top-level event is linked to a psychological event, which connects the psychological to the quantum. Each human conscious experience is seen as a ‘feel’ of an event in the top level of processing in the human brain.
Consciousness & Chance
Stapp sees the physical world as a structure of tendencies or probabilities within the world of the mind. He thinks that the introduction of an irreducible element of chance into nature via the collapse of the wave function, as described in most forms of quantum theory, is unacceptable. The element of conscious choice is seen by him as removing chance from nature.