The fundamental issue in the debate between materialists and design theorists is metaphysical. What is the basic nature of things that exist, and how did they come about? If we make a mistake on these basic metaphysical questions we can’t hope to get the questions or the answers that follow from them right. If our metaphysics is wrong, our physics and biology and neuroscience will be wrong, too.

My colleague David Klinghoffer has an excellent post in which he asks this question of fundamental importance: What is matter? He quotes astrophysicist Adam Frank:

Materialists appeal to physics to explain the mind, but in modern physics the particles that make up a brain remain, in many ways, as mysterious as consciousness itself.

When I was a young physics student I once asked a professor: “What’s an electron?” His answer stunned me. “An electron,” he said, “is that to which we attribute the properties of the electron.” That vague, circular response was a long way from the dream that drove me into physics, a dream of theories that perfectly described reality. Like almost every student over the past 100 years, I was shocked by quantum mechanics, the physics of the micro-world. In place of a clear vision of little bits of matter that explain all the big things around us, quantum physics gives us a powerful yet seemingly paradoxical calculus. With its emphasis on probability waves, essential uncertainties and experimenters disturbing the reality they seek to measure, quantum mechanics made imagining the stuff of the world as classical bits of matter (or miniature billiard balls) all but impossible.

Like most physicists, I learned how to ignore the weirdness of quantum physics. ‘Shut up and calculate!’ (the dictum of the American physicist David Mermin) works fine if you are trying to get 100 per cent on your Advanced Quantum Theory homework or building a laser. But behind quantum mechanics’ unequaled calculational precision lie profound, stubbornly persistent questions about what those quantum rules imply about the nature of reality — including our place in it.

Those questions are well-known in the physics community, but perhaps our habit of shutting up has been a little too successful. A century of agnosticism about the true nature of matter hasn’t found its way deeply enough into other fields, where materialism still appears to be the most sensible way of dealing with the world and, most of all, with the mind. Some neuroscientists think that they’re being precise and grounded by holding tightly to materialist credentials. Molecular biologists, geneticists, and many other types of researchers — as well as the nonscientist public — have been similarly drawn to materialism’s seeming finality. But this conviction is out of step with what we physicists know about the material world — or rather, what we don’t know…

What exactly is quantum mechanics telling us about the world? What does the wave function describe? What really happens when a measurement occurs? Above all, what is matter?

Dr. Frank is asking the right question. What is matter?

The materialist conception of matter derives in part from Democritus and Lucretius (two ancient materialist philosophers), but I believe that the most cogent view of matter as held by modern materialists is that of Descartes.

Descartes defined matter as res extensa — literally, substance extended in space. Matter, in the Cartesian view, is characterized by extension — length, width, and depth, and by associated properties such as mass that accompany extension in space. In the Cartesian view, all subjective mental properties, such as qualia and intentionality, were defined away — excluded — from matter itself. How, then, could the mind exist if subjective properties had no basis in matter? In order to explain subjective experience and the mind, Descartes posited the existence of a second substance, res cogitans, which entailed subjective mental experience and which was composed to matter in human beings. This was Cartesian substance dualism. The body and the mind were separable substances, each existing in its own right. Furthermore, Descartes believed that only humans had minds. Animals were automatons, essentially mindless machines made of meat.

Famously, Descartes’ view of man as a composite of two separated substances, one extended in space, the other mental, gave rise to the interaction problem (the “ghost in the machine”): How can mental substance interact with material substance? Modern materialists have discarded Descartes’ mental substance, and have tried to explain nature and consciousness via matter alone. Modern materialists are Descartes’ descendants: although they have discarded Cartesian dualism, they retain Cartesian materialism. To the modern materialist, what really exists is matter extended in space, tangible stuff, and all intangible stuff (like the mind) needs to be explained in terms of tangible matter. Hence the bizarre cornucopia of materialist theories of mind, such as philosophical behaviorism, identity theory, computer functionalism, and eliminative materialism. Each materialist theory of mind is abject nonsense.

Materialist metaphysics, derived from Cartesian res extensa, constrains materialist physics, biology, and neuroscience. Doing science and philosophy from the perspective of materialist metaphysics is like swimming with lead weights. Materialist metaphysics is constantly pulling materialists down, and keeping them from getting anything right and from really understanding nature.

Materialism is a conceptual catastrophe. How, from a materialist perspective, can we explain the laws of physics? How can we explain abstract things, like universals and mathematics, if all that exists is matter extended in space? How can the mind arise from matter — how can meat think? How can we square the materialist understanding of nature with quantum mechanics, which reveals very non-materialist properties of matter at its most fundamental level?

Materialism isn’t really a metaphysical theory. It’s just a mistake. It’s a woefully inadequate understanding of nature.

So how can we understand matter, nature, and the mind? There is another way of understanding matter, which is the way of Aristotle. That is my topic for a post tomorrow.

Image: René Descartes, by Frans Hals [Public domain], via Wikimedia Commons.