Will and quantum physics

Henry Stapp

Lawrence Berkeley National Laboratory, University of California, Berkeley

Attention, Intention and Will in Quantum Physics

Journal of Consciousness Studies, 6, Nos 8-9, pp. 143-64


Stapp starts by taking the view that the mind/matter problem represents a conflict between classical physics and our own intuitions. In classical physics we have to be automatons, while our intuition tells us that we are in charge of our actions. The dominant paradigm in neuroscience and philosophy is based on classical physics and attempts to explain away the intuition of free will. Stapp, however, thinks it is necessary to bring in a form of quantum theory, which emphasises the importance of the observer. This yields a theory that is much closer to our intuitions. The need for a self-observing quantum system to ask particular questions produces a causal opening for mind/brain dynamics.


Classical physics was based on the concept of bits of material localised in small regions, with all of the motion of these bits of matter determined by other bits of matter. The local character of this form of physical law was a central feature. The localised bits of matter respond only to their immediate neighbours, and not at all to more distant objects. The evolution of the physical universe is governed by the totality of these local processes.


Stapp takes the view that the success of classical physics in the 18th and 19th centuries has dazzled modern philosophers, so that they see it as part of their role to explain away consciousness. The dominant role of philosophers in the science of consciousness is itself interesting. While philosophers may have a useful role to play in interpreting science, it is difficult to think of another scientific area, where hypothesis put forward by scientists and medical experts would be openly ridicule, without bothering to attempt any serious analysis of the ideas put forward.


Stapp reminds us that the assumptions of classical theory mentioned above are now known to be incorrect. Stapp believes that quantum theory can provide a better understanding of the mind brain problem. However, he agrees the quantum randomness is not a useful feature as it would be destructive of rational behaviour.


The original Copenhagen Interpretation of quantum theory was thrashed out at the Solvay Conference of 1927. It was agreed that the wave function represented our knowledge of the system, and the particle after collapse of the wave function represents a more precise knowledge of the system as a result of the measurement. Our knowledge, in this interpretation, is knowledge of a mathematical theory, and not knowledge of a real world of particles and fields. The mathematical formulas were to be seen as representing the knowledge of the human observers rather than external real events.The Copenhagen Interpretation became the mainstream consensus for much of the 20th century, but it has become less invariably accepted in recent decades, and Penrose is prominent amongst the physicists rejecting Copenhagen. Stapp, however, holds to an interpretation close to Copenhagen. The difference between Penrose and Stapp in the fundamental interpretation of quantum theory means that their concepts are essentially different, quite apart from any differences as to which brain functions are involved in quantum activities. In particular, Stapp’s theory only holds up if we accept a theory that is close to Copenhagen.


Stapp discusses the amendments to Copenhagen introduced by von Neumann. Von Neumann brought the human observer into the physical system of the quantum state. Most other efforts to amend Copenhagen sought to exclude the consciousness of the observer, which would bring the theory more closely into line with the attitude of classical physics. Despite this change by von Neumann, the basic concept of Copenhagen was retained, that is that the quantum is to do with knowledge, and reductions in the quantum wave are necessary for any increase in knowledge. There is thus a link between the reduction of the quantum wave and an increase in knowledge in the consciousness of the observer.


Stapp goes on further to discuss the role of the observer in traditional interpretations of quantum theory. The ‘Heisenberg Choice’ is Heisenberg’s 1927 idea that the observer in quantum theory chooses the questions that will be put to nature. The original Schrödinger equation does not specify where and when the question leading to reduction will come, so the question has to come from the observer.


Presumably on the basis that the Copenhagen version of quantum theory is based on our knowledge of the system, Stapp, in line with quite a large body of modern physicists, sees information as the basic currency of reality. The basic unit of information is taken to be the ‘bit’, which is the answer ‘yes’ or ‘no’ to some question.


Stapp, drawing on studies of infants, assumes that humans have a hard-wired body-world schema. Consciously directed action is seen as a projection of this body-world schema into the future, with a corresponding representation in the brain. This body-world schema is seen as directing the unconscious brain, issuing commands for motor action and instructions for mental processing. On going questions to nature continue to be posed by the observer. This equates to the ‘Heisenberg Choice’ where the human observer has to decide what question to put to nature. In this case, it is the conscious processing in the brain that does this. Each experience leads to further updating of the system. When an action is initiated by a thought, this usually includes some monitoring of the subsequent action, to check it against the intended action. So something experienced as an intention becomes an action, the attention to which is also experienced.Stapp views the deterministic unfolding of matter according to the Schrödinger equation as running parallel to the movement from intention to attention as two poles of the same quantum event. He also sees a tripartite structure being the Schrödinger equation, the Heisenberg choice of question to ask and the (Dirac) choice of answer from Nature. Stapp’s point is that only a conscious observer within the brain can ask the question and drive the quantum process. This also allows the experiental process to enter into the causal structure of the body brain. Stapp feels that some additional process is needed and the conscious observer is a perfect candidate. He sees quantum theory as informational in nature, and thus linked to increments in knowledge occurring in the brain. The increment in knowledge is seen as linked to a reduction in the quantum state, thus linking the mind to the physical world. The mind is therefore seen as entering into the physical world through the Heisenberg choice.


When the quantum state is reduced a wave that extends over an indefinite amount of space is instantaneously reduced to a tiny local region. Stapp feels that this constitutes a representation of knowledge, rather than a representation of matter. The wave before collapse is seen as a matter of potentiality or probabilities, which are themselves often conceived as ideas rather than realities. However, the quantum state pre-collapse evolves in line with the deterministic Schrödinger equation giving the state some of the properties of the physical, and creating a hybrid. Stapp opines that the evolution of the system can be significantly influenced by the choice and timing of the questions put to nature by the observer.


Stapp does not suggest that our conscious thoughts are completely unconstrained, but he does see our thoughts as a part of the causal structure of the mind-brain that is not dominated by the actions of the smallest components of the brain, but is also not a random effect. Our thoughts are seen not as linked to external objects, but instead linked to patterns of brain activity. Stapp points out that his theory has a place for an efficacious conscious mind linked to the physical processes of the brain.


In the latter part of his article, Stapp does attempt to address the problem of what happened when there were no human minds to poses questions of nature. He suggests that the dynamic of the Schrödinger evolution, which is to produce an event that replicates the event that produced it, could somehow stand in for the later action of conscious minds. On the surface of it, this does not seem very convincing, since the rest of article has been stressing the difference between the questions posed by conscious minds and their timing on their one hand and the determinism of classical physics as applied to the brain on the other hand.


The problem with Stapp’s theory and with the whole Copenhagen influenced interpretation of quantum theory is the apparent dualism. Mathematics can be seen as a mental process instantiated in protein, which cannot directly influence the external world. Somehow the mathematical description of the quantum waves is sitting out there in space and then as a result of a measurement becomes a physical object, in the form a quantum particle. The problem is really the same as with dualism. In Copenhagen a mental concept external to the body becomes physical with no explanation as to how the two could interact. In dualism, the spirit stuff and the material stuff are supposed to act on one another, but it is not clear how, without one taking on some of the characteristics of the other, at which point the system is no longer dualistic. The Copenhagen system has the additional problem of what was happening before human minds emerged, for which Stapp’s explanation appears rather sketchy.
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