Mind and consciousness are often used interchangeably but refer to different aspects of human cognition and awareness. The mind encompasses thoughts, memories and cognitive functions while consciousness is an awareness of these processes. Are mind/consciousness amenable to explanation by physics? Stephen Barr, professor of theoretical particle physics, thinks not.
Most scientists believe in “physicalism“, also called “scientific materialism“, the idea that all reality, human mind included, is ultimately nothing but matter and its interactions and explicable by physics. But Barr explains that consciousness may be something as fundamental as matter but not reducible to matter.
Physics, the most basic of the sciences, discovers the laws that determine the behaviour of the physical world and has achieved an ever-more unified conception of physical phenomena. Thus, Newton’s laws (17th century) are “universal”, applying to matter throughout the universe and “deterministic” because they determine how events will unfold from any given starting point. The laws of physics discovered in the two centuries after Newton are also deterministic, giving rise to the belief that physical effects are entirely accounted for by prior physical causes – the principle of “causal closure” of the physical world.
Nevertheless, many scientists persisted in thinking that life and mind are exceptions, involving non-physical principles and forces. However, 19th and 20th century discoveries showed that the chemistry of living cells is based on the same chemical laws that apply in the nonliving world.
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And, applying the principle of physical closure implies our thoughts must also be physical entities, because our thoughts affect our actions and therefore affect the physical world. And so, the idea that minds are simply physical machines and thoughts are electrical signals took firm root.
Physicalism offers a simple explanation of all reality satisfying the human desire for simplicity in our understanding of the world. Striving for unity of understanding has been wonderfully successful in physics. Thus, Newton’s laws govern terrestrial and celestial phenomena. James Clerk Maxwell showed in the 1880s that electricity, magnetism and optics are aspects of the single force “electromagnetism“. Einstein in 1905 and 1915 showed mass and energy are the same thing, and space and time form a four-dimensional whole. And physicists are now working on a theory of everything to explain all reality, mind included.
Consciousness/mind is intimately connected to the brain, tempting one to think certain arrangements of matter cause consciousness to arise. But is this physical causation, the kind that physics can explain? Barr posits strong reasons to think not. For example, science can measure dopamine levels in the brain. We know that lowered dopamine levels cause feelings of boredom but these feelings are not calculable using equations of physics. Many famous scientists such as Erwin Schrodinger (1887-961) thought consciousness would never be explained by physics.
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Barr, quoting cosmologist Andrei Linde points out we may be pushing physicalism too far in asking it to account for the mind, because this ignores the primacy of perception.
Our knowledge of the world begins with perception (eg, we see different colours), not with matter. Later, we find our perceptions obey laws formulated by assuming there is some underlying reality beyond our perceptions. This model of the material world, operating to the laws of physics, is so successful we forget about our starting point of perception and conclude that matter is the only reality. Perception is demoted to a tool for describing matter. This assumption could be false. Both matter and consciousness are features of the natural world but consciousness/mind may not be reducible to matter.
But if matter and consciousness are both features of the material world, is there not a unifying explanation of both? Although this is a reasonable expectation, a unifying explanation of two things doesn’t entail reducing one to the other. For example, the established theory of electromagnetism provides a unified understanding of electromagnetic fields and electrically charged particles but describes each as discreet and equally fundamental realities. It doesn’t say one can be reduced to or is composed of the other.
Finally, there is the possibility that ongoing scientific investigations of near-death experiences (NDE), described in my last column, will dramatically demonstrate the reality of non-physical human mind/consciousness. Some NDEs describe the mind leaving the body in the hospital operating theatre and looking down on it from above. Controlled experiments are testing such reports.
William Reville is an emeritus professor of biochemistry at UCC