I’ve been squabbling about realism lately, with myself as well as with others. I don’t mean realism in the colloquial sense, meaning hardheadedness, or political realism, which assumes we’re all selfish jerks. (Hypothesis: political realists are jerks who project their jerkiness onto everyone else.)
No, I mean realism in the hifalutin philosophical sense, which assumes that the world has an objective, physical existence, independent of us, that we can discover through science. This position is sometimes called scientific realism or, by critics, naive realism.
Philosophers will probably object to my definition, but philosophers object to any definition. That’s what philosophers do. In this column I’ll present a few thoughts on realism, in the hope that they help me reach a conclusion that satisfies me, if no one else.
REALISM AND THE END OF SCIENCE
When you present the realist position to nonphilosophers, they often react with some equivalent of: Duh, what idiot doubts that there is a real world out there and that science discovers it? Actually, many people object to realism, and some are quite clever.
Antirealism can take many different forms, including postmodernism, which denies that absolute truth is attainable and brackets “scientific knowledge” in scare quotes; idealism, which says mind is more fundamental—more real! —than matter; and the simulation hypothesis, the idea that we’re living in a virtual reality, like The Matrix. Although antirealist perspectives vary, most suggest that objective, physical “reality” is illusory or unknowable.
Realism is a central premise of my 1996 book The End of Science. Scientists have constructed a map of nature so accurate, so true, I contend, that it is unlikely to undergo significant revisions. We have discovered, not merely imagined, features of nature such as electrons, atoms, elements, DNA, bacteria, viruses, neurons, gravity and galaxies. These things are real; they exist whether or not we believe in them, and only fools and philosophers would dare to claim otherwise. I dismiss the claim of Thomas Kuhn, a pioneer of postmodernism, that science never gets a firm grip on reality and hence is always ripe for revolution.
Then, beginning last summer, I dove into quantum mechanics. This project has thrown me for a loop, forcing me to question my commitment to realism. Quantum mechanics accounts for countless experiments, and its applications have transformed our world. Many physicists think that quantum mechanics represents the final framework for physics. No matter how his field evolves, Steven Weinberg told me in 1995, “I think we’ll be stuck with quantum mechanics.”
Experts cannot agree on what quantum mechanics tells us about the nature of matter, energy, space, time and mind. Some interpretations challenge the realist assumption that reality is strictly physical. I just finished the marvelous little book Q Is for Quantum, in which physicist Terry Rudolph boils quantum mechanics down to its odd mathematical essence. Quantum mechanics, Rudolph says, makes it hard to sustain the “naive realistic belief” that the universe “has physical properties of some form independent of my concerns.”
In The End of Science, I say that particle physics “rests on the firm foundation of quantum mechanics.” Firm foundation? Ha! The more I ponder quantum mechanics, the more physics resembles a house of cards. Floating on a raft. On a restless sea. Physics seems wobbly, ripe for revolution, for a paradigm shift that sends science veering off in unexpected directions.
ALL NUMBERS ARE IMAGINARY
My quantum experiment has also made me suspicious of mathematical models of reality. The Schrödinger equation, for example, employs so-called imaginary numbers, multiples of the square root of –1. My efforts to understand how imaginary numbers map onto the real world have led me, perversely, in the opposite direction. Instead of imaginary numbers becoming more real, real numbers, which fall on a line extending from positive to negative infinity, are becoming less real.
“If the inclusion of imaginary numbers is worrying,” philosopher R.I.G. Hughes writes in The Structure and Interpretation of Quantum Mechanics (recommended by Jim Holt, one of my quantum advisors), “it is worth considering the sense in which a negative number, –6 say, is real—or, come to that, the sense in which 6 itself is real.” Hughes cites Bertrand Russell’s definition of mathematics as “the subject in which we never know what we are talking about, nor whether what we are saying is true.”
Physicists Gerard ‘t Hooft and Sheldon Glashow make similar points in a recent online exchange, “Confusions Regarding Quantum Mechanics.” ‘t Hooft calls real numbers “artificial,” manmade” and “arbitrary,” suggesting that they give us a sense of false, unwarranted precision. Glashow points out that ‘t Hooft “is not the first to question the reality of real numbers.” He cites mathematician Gregory Chaitin and physicist Nicolas Gisin, who have also suggested that “real number” might be an oxymoron.
These remarks undercut the realist claim that mathematical theories like quantum mechanics and general relativity work because they mirror nature. Perhaps we should view the theories as calculating devices that predict experimental outcomes but have an obscure relation to reality, whatever that is.
DOES “MATTER” COME FROM MIND?
No wonder, then, that some scientists and philosophers have challenged scientific realism and its corollary, materialism, which decrees that reality consists of matter. Quantum theorist John Wheeler proposes that we live in a “participatory” universe, in which our questions and observations define reality and even bring it into existence. QBism (pronounced like the art movement) suggests that quantum mechanics represents our subjective perception of the world. And your perception isn’t necessarily the same as mine.
I recently participated in an online symposium with idealist critics of materialism, including philosopher Bernardo Kastrup and psychologist Donald Hoffman, authors, respectively, of Why Materialism Is Baloney (love that title) and The Case Against Reality. These authors contend that “matter” stems from mind rather than vice versa. Atheists like Richard Dawkins deride Deepak Chopra, the spirituality and health mogul, for insisting that reality consists of consciousness. Wouldn’t it be funny if Chopra turned out to be right and Dawkins wrong?
Mystical experiences seem to corroborate mind-centric metaphysics. Many mystics come away from their visions convinced that our everyday material world, consisting of people and other things, is illusory, and that a “cosmic consciousness” transcending that of any individual lies at the bottom of things. My psychedelic experiences make me sympathetic toward this idealist view. One trip left me wondering whether our “reality” is actually virtual, the fever dream of an insane God.
REALISM AND WHAT REALLY MATTERS
And yet. Although my realism has been wobbling lately, I remain a realist. Before I explain why, I need to make a point that is subtle, perhaps incoherent. Here goes. There is something tendentious, question-begging and contradictory about the terms “real,” “realism” and “reality.” When you say, “This is real” or “This is reality,” you are implicitly saying, “This is what matters.” Ostensibly, you are making a claim about what is objectively real, and hence true. Actually, you are making a subjective value judgment.
Take, for example, What Is Real?, a terrific book on quantum mechanics by Adam Becker. That title reflects physicists’ judgment that their work represents knowledge-seeking at its most profound. Many physicists still believe that one day they will discover a complete, consistent account of the physical realm, which some call a “theory of everything.”
The absurdity of that phrase! If physicists ever find such a theory (a big if), it will tell us nothing about death, sex, love, fear, war, justice, beauty and other deep, defining features of the human condition. These matter more, and hence are far more real, than wave functions or dark energy. Pride and Prejudice and Ulysses—works of fiction!—tell us more about our messy, painful human reality than physics ever will. (And please don’t send me links on “quantum social science.”)
But some antirealist perspectives, including the simulation hypothesis and my own psychedelic theology, are equally absurd—and even, I would argue, immoral. When they suggest that our material world is an illusion, they trivialize human suffering and injustice, and they undermine our motives for making the world a better place.
Another insidious effect of antirealism—and this is especially true of postmodernism—stems from its claim that scientific “knowledge” reflects our subjective fears, desires and biases. There is some truth to this assertion, of course. Scientists’ lust for fame, glory and money can corrupt them. Moreover, as I emphasize in Mind-Body Problems, we can’t escape our subjectivity when we try to understand ourselves. But taken too far, postmodernism can undercut efforts to analyze and solve all-too-real problems like climate change, economic inequality, militarism and the COVID-19 pandemic.
Filmmaker Errol Morris, who studied under Kuhn in the 1970s and ended up loathing him, contends that Kuhnian-style postmodernism makes it easier for politicians and other powerful figures to lie. Philosopher Timothy Williamson makes a similar point in “In defence of realism.” “Imagine a future,” Williamson writes, “where a dictator or would-be dictator, accused of spreading falsehoods, can reply: ‘You are relying on obsolescent realist ideas of truth and falsity; realism has been discredited in philosophy.’”
Philosopher Michael Strevens sticks up for scientific realism in his insightful new book The Knowledge Machine: How Irrationality Created Modern Science. The “radical subjectivists,” Strevens notes, can “explain everything about the messy human business of scientific inquiry except what matters most: the great wave of progress that followed on the Scientific Revolution. Medical progress, technological progress, and progress in understanding how it all hangs together, how everything works. Immense, undeniable, life-changing progress.”
Yes, that’s the same argument I made in The End of Science, and that I continue to make to my postmodern pals. So, I’d like to reiterate my support for a particular kind of realism, a pragmatic, ethical realism, which acknowledges science’s power as well as its fallibility and puts mortal, troubled humanity at the center of things. Like democracy, realism is flawed, but it beats the alternatives.
Postscript: My Stevens Institute colleagues Greg Morgan and Michael Steinmann, who are philosophers, and James McClellan, a historian of science, have labored mightily (and they probably think in vain) to make my realism less naive. Thanks guys!
Over the last year I’ve discussed realism-related issues on my podcast “Mind-Body Problems” with a wide range of thinkers, including Michael Brooks, George Musser, Amanda Gefter, Adam Becker, Philip Goff, Jeffrey Kripal and Errol Morris.
This is an opinion and analysis article.
Scientific American Content: Global