Quantum Leaps in Philosophy of Mind: Reply to Bourget’s Critique

Henry Stapp

Lawrence Berkeley Laboratory

Journal of Consciousness Studies, 11, No. 12, pp. 43-9

In this paper, Stapp addresses Bourget’s criticism of the idea, derived from von Neumann, that the original Copenhagen interpretation of quantum theory needed to be supplemented by the conscious choice of the observer.

Stapp stresses that he adheres to orthodox physics and disagrees with Eccles suggestion that the physical law can be biased by a non-physical mental effort. Stapp says that his objective is to identify how patterns of neural excitation are excited. Stapp considers that the selection contains a willful element and a statistical element. The willful element is the so-called Heisenberg choice.

The second part is what the physicist, Dirac, referred to as ‘a choice on the part of nature’. Stapp’s theme is that the collapse of the wave function that results in the particular position of a particle being chosen is not determined by the laws of quantum theory. In the von Neumann interpretation of quantum theory the timing of the wave function collapse is determined by the experimenter and the choice of position for the particle, the projection operator, is random.

Stapp sees these elements as providing a dynamical gap that allows mental effort to influence brain activity. He thinks that the choice of when the wave function collapse occurs, and what the projection operators decides is a joint effort of the mental and physical aspects of the brain. Freewill comes in at this level which is not statistically controlled. In particular, Stapp thinks that mental effort could effect the rapidity of the collpase of the wave function, and this is relevant to findings in psychology and neuroscience that have a bearing on mental effort and will (Schwartz et al, 2003) (1).

Stapp moves on to discuss the difficult question of what is the mental agent that determines the rapidity of collapse. In practical terms, this is mental effort, but what is this mental effort. Stapp does not rule out the possibility of discovering a physical determinant of the wave function collapse, but points out that science has not been able to find this during a period of 25 years, because the mathematical basis of the theory ties it to probabilities rather than certainties. In Copenhagen the evolving wave function is not enough to specify reality, and human choices have to enter into the flow of events. Thus choice comes not from a mechanical process, but partly from an evaluative process, which is what we experience as happening.

There could be two reservations with regard to Stapp’s work. First, it is based on a version of Quantum Theory which is close to Copenhagen. Many modern physicists dislike this approach, mainly because of the dualistic way in which the real universe somehow arises from mathematical concepts. Even if this is allowed, on the basis that it is still to some extent a mainstream interpretation of physics, the theory is blatantly dualistic in that the mental agent the decides the rapidity of the wave function collapse is stated to be most likley non-physical.


(1) Schwartz et al, (2003) The volitional influence of the mind on the brain in Consciousness, Emotional Self-Regulation and the Brain..ed. M. Beauregard John Benjamins

Schwartz et al, (2004) Quantum physics in neuroscience and psychology

Bourget, D. (2004) Quantum leaps in philosophy of mind Journal of Consciousness Studies, 11 (12) pp. 17-42

Stapp, H (1993) Mind, Matter and Quantum Mechanics

Stapp, H. (1997) Science of consciousness and the hard problem Journal of Mind and Behaviour, 18, (2-3) pp. 171-94

Stapp, H. (1999) Attention, intention and will in quantum physics Journal of consciousness Studies, 6, (8-9) pp. 143-64

Stapp, H. (2001) Quantum Theory and the role of mind in nature Foundation of Physics, 31, pp. 1465-99

Stapp, H. (2004) Quantum approaches to consciousness in Cambridge Handbook of Consciousness ed. M. Moskovitch & P. Zelato www.physics.lbl.gov

Stapp. H. (2004) The Mindful Universe

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