Stapp’s Collapsing the Wave Function via Asking “Questions”

Mathematical physicist Henry Stapp argues for the quantum nature of consciousness by relying on a traditional interpretation of quantum mechanics, where quantum wave functions collapse only when they interact with consciousness in an act of measurement. He envisions a “mind-like” wave-function collapse that exploits quantum effects in the synapses between neurons, generating consciousness, which he believes is fundamental to the universe (Stapp, 2011, 2023, 2007.)

Classical vs. Quantum Physics Foundations

Stapp founds his theory on the transition from the classical-physics conception of reality to von Neumann's application of the principles of quantum physics to our conscious brains (Stapp, 2006; Von Neumann, 1955/1932). Von Neumann extended quantum theory to incorporate the devices and the brain/body of the observers into physical theory, leaving out only the stream of conscious experiences of the agents.

According to von Neumann's formulation, “the part of the physically described system being directly acted upon by a psychologically described ‘observer’ is the brain of that observer” (Stapp, 2011).

The quantum jump of the state of an observer's brain to the ‘Yes’ basis state (vector) then becomes the representation, in the state of that brain, of the conscious acquisition of the knowledge associated with that answer ‘Yes,’ which constitutes the neural correlate of that person's conscious experience. This fixes the essential quantum link between consciousness and neuroscience (Stapp, 2006).

To Stapp, this is the key point. “Quantum physics is built around ‘events’ that have both physical and phenomenal aspects. The events are physical because they are represented in the physical/mathematical description by a ‘quantum jump’ to one or another of the basis state vectors defined by the agent/observer's choice of what question to ask.

If the resulting event is such that the ‘Yes’ feedback experience occurs then this event ‘collapses’ the prior physical state to a new physical state compatible with that phenomenal experience” (Stapp, 2006).

Thus, in Stapp's telling, mind and matter thereby become dynamically linked in a way that is causally tied to an agent's free choice of how to act. “A causal dynamical connection is established between (1) a person's conscious choices of how to act, (2) that person's consciously experienced increments in knowledge, and (3) the physical actualizations of the neural correlates of the experienced increments in knowledge” (Stapp, 2006).

More colloquially, Stapp argues that given the perspective of classical physics, where all is mechanical, where the physical universe is a closed system, “there's nothing for consciousness to do … and so it must be some sort of an illusion.” Why would there have been consciousness at all, he asks? Under classical physics, “consciousness is just sitting there inert, a passive observer of the scene in which it has no function; it does nothing. So, it's a mystery why consciousness should ever come into existence” (Stapp, 2007).

Consciousness as Question-Asking

In stark contrast, Stapp says, the way quantum mechanics works, in order to get consequences, predictions, there must be a question posed. It's like “20 questions,” yes-or-no questions. A question is posed in the quantum mechanical scheme; then there is an evolution according to the Schrodinger equation, and then nature gives an answer (which is statistically determined).

The axial idea, Stapp says, is that there is nothing in quantum mechanics that determines what decides the questions. This means that there's a gap, a critical causal gap in quantum mechanics. And the way it's filled in practice is that an observer, on the basis of reasons or motivations or with rules, sets up a certain experiment in a certain way. For example, putting a Geiger counter or some other detector in the path of particles.

This yields Stapp's concept of quantum consciousness. Nobody denies that thoughts exist, he says, but how do they do something? And that's the place where quantum consciousness has causal impact.

The crux of quantum mechanics is what questions are going to be asked. There is nothing in classical physics that asks such questions. But in quantum mechanics questions are answered by the psychological process of the experimenter, who is interested in learning something. And because there is nothing in the way quantum mechanics works that explains the choice of the question, there is an opening for the injection of mental events into the flow of physical events. The choice of the question is not determined by the laws as we know them (Stapp, 2007).

This means we need another process, which is consciousness. And this gives consciousness an actual role to play and allows it to do things causally. And if consciousness can act causally and do things, Stapp says, then classic materialism is out.

Niels Bohr had a famous quote: “one must never forget that in the drama of existence we are ourselves both actors and spectators.” In the classical worldview, Stapp says, “we were just spectators; always we would just watch what's happening but couldn't do anything. In the quantum mechanical worldview, we are actors. We are needed to make the theory work.”

Moreover, Stapp says, “this mental process cannot just be the product of the brain, because the brain, like all physical things, evolves via quantum mechanical rules. While quantum mechanics describes the evolution of potentialities for events to happen, that's all they describe, only potentialities—they do not describe what chooses the events that are going to happen, the actual events. Something must ask the questions, something outside of quantum mechanics—quantum mechanics forces that process.” The only candidate, Stapp says, must be the independent existence of consciousness (Stapp, 2007).

Stapp's conclusions are as bold as they are controversial. First, the ontological foundations of consciousness and quantum mechanics are inextricably linked. Second, classical materialism is defeated (Stapp, 2007).

Critiques and Alternatives

Philosopher of physics David Wallace is sympathetic with the idea that consciousness with respect to quantum physics has to be taken somehow as fundamental and irreducible, but there are two different ways that could go. “There's the dualist way, where you have physics and you have consciousness as two separate things, and there's the panpsychist idea, where consciousness underlies all of physics and is present at the most fundamental level of every physical process. Those are two different ideas” (Wallace, 2016a, 2016b).

When Wallace thinks about consciousness collapsing the wave function, as in quantum mechanics, he says, “That's the dualist half of my head. You've got physics, you've got a wave function, and you've got consciousness, which is observing the wave function. And somehow consciousness is something distinct from the physical wave function and every now and then affecting it in this interesting phenomenon of collapse. In a way, it's an updated version of Rene Descartes's dualism: there's mind and then there's body; they're separate and they interact.”

Wallace says one could try to combine dualism and panpsychism with respect to the relationship between consciousness and quantum mechanics, “but I don't think they'd combine all that well,” he said. “If consciousness is everywhere and consciousness collapses the wave function, then the wave function would be constantly collapsing and we know that doesn't happen because you get interference effects in double slit experiments. So, I think these two ideas, panpsychism and consciousness collapsing the wave function, should be pursued on separate tracks (Wallace, 2016a, 2016b, 2016c.)