The Infinite Optimism of David Deutsch
One thing that bothers me about Deutsch’s outlook is that it’s too easily reducible to slogans like this, which I came upon in The New Yorker this morning.
HOBOKEN, NEW JERSEY, SEPTEMBER 30, 2025. I spent last week in Philadelphia at “Rat Fest,” whose attendees share an enthusiasm for “critical rationalism,” Karl Popper and David Deutsch. Rat (short for rationalism) Fest was a trip, I’ll report on it soon. In the meantime, here’s an edited version of my 2011 Wall Street Journal review of Deutsch’s book The Beginning of Infinity, which should give you a sense of how Deutsch and Rat Festers see things. —John Horgan
How far can we go? In science, mathematics, technology, medicine, the arts, ethics, politics? Can these endeavors, which constitute modern civilization, advance indefinitely, even forever? Or will they eventually bump into limits? I have a weakness for such impossibly grand questions, and so does physicist David Deutsch.
In The Beginning of Infinity, Deutsch argues even more vigorously for the many-worlds interpretation of quantum mechanics than he did in his first book, The Fabric of Reality. All those other worlds aren’t just possible, Deutsch insists, they are actual. But Beginning ranges far beyond physics. Deutsch’s primary goal is laying out his radically optimistic vision of humanity's future, in which progress continues forever.
I was primed to trash Deutsch’s book. I don’t dig many worlds or any multiverse theories, which I think of as science fiction with equations. And Deutsch knocks my 1996 book The End of Science, which proposes that the glory days of science—and especially pure science, the effort to map out and understand reality—may be over. Deutsch equates my thesis with “dogmatism, stagnation and tyranny”--all of which, for the record, I’m against.
But Deutsch makes the case for infinite progress with such passion, imagination and quirky brilliance that I couldn't help but like his book. More often than not I found myself agreeing with him—or at least hoping that he’s right.
Deutsch points out that for most of history--apart from a few brief, shining exceptions, like ancient Athens—knowledge scarcely evolved. Conformity and conservatism reigned, and innovation was suppressed, often brutally.
But several centuries ago, Enlightenment figures such as Galileo, Newton and Voltaire helped propagate an extremely powerful way of solving problems. You propose an explanation of reality, criticize and test it, pose a new and ideally improved explanation, criticize that one and so on.
Through this recursive process, we began to accumulate extraordinary insights into and power over nature, as embodied by the scientific and industrial revolutions. We also advanced in the political realm, replacing monarchies and other archaic forms of governance with more just, representational systems.
The greatest threat to continued progress, Deutsch contends, is our belief that we can achieve—or, worse, have achieved--final solutions. We must accept that we are all fallible, and hence all our knowledge is tentative and improvable.
Deutsch rejects end points of all kinds, whether a “theory of everything” that answers every scientific riddle; a utopia that optimizes human happiness; a work of art so exquisite that it cannot be surpassed; or even the Buddhist version of Enlightenment, a state of unsurpassable spiritual grace.
If we acknowledge our imperfections, Deutsch says, then, paradoxically, there is no problem we cannot tackle. Examples: the mind-body problem, which has stumped philosophers going back at least to Socrates; the unification of the two major pillars of modern physics, quantum theory and general relativity; mortality (yes, really); and climate change.
We can overcome global warming through innovation, Deutsch says, rather than drastic cutbacks in fossil-fuel consumption. I felt guiltily entertained as Deutsch gored the sacred green cow of “sustainability,” which he views as a synonym for stagnation. Societies are healthiest, he declares, not when they achieve equilibrium but when they are rapidly evolving.
Making the case for science’s open-endedness, Deutsch mounts a compelling challenge to scientific reductionism, which decrees that all phenomena can be explained in terms of their physical components. Yes, atomic theory, chemistry and genetics have worked spectacularly well at explaining many features of nature.
But small-scale processes, Deutsch points out, spawn so-called emergent phenomena that require understanding on their own terms. Bodies give rise to minds, which in turn give rise to ideas, which have no specific physical instantiation but can nonetheless influence human behavior in profound ways.
Deutsch's emphasis on mind’s irreducibility dovetails with his insistence that progress stems from unconstrained human creativity. Although we are subject to the laws of nature, Deutsch acknowledges, we can nonetheless control our destiny through our own free choices.
This position might not seem terribly controversial, but scientists like Albert Einstein, Francis Crick and Stephen Hawking have argued that free will is an illusion. They say our “choices” actually stem from physical processes beyond our conscious control. I am heartened that Deutsch resists this appalling scientific determinism.
Deutsch's book is, as his own philosophy stipulates, imperfect. He rejects appeals to authority but constantly defers to philosopher Karl Popper. When I interviewed Popper in 1992, I found him to be a weirdly dogmatic opponent of dogmatism.
Now and then, Deutsch’s reasoning becomes ponderous to the point of opacity. And his optimism sometimes resembles that of a man standing on a mountaintop, conveniently distant from the problems afflicting those of us in the lowlands.
Physics, for example, has stalled not for lack of a can-do spirit but for mundane material and economic reasons. Taxpayers and politicians have become reluctant to build the gigantic, expensive accelerators that might help physicists forge past current theories. Lacking experimental guidance, theorists have wandered into increasingly arcane, untestable speculation.
I’m more upbeat about the future of neuroscience, which has the potential to yield discoveries with revolutionary philosophical and practical import. But neuroscientists have yet to crack the code of the brain, which seems to become more dauntingly complex the more we learn about it. And consciousness remains a riddle.
When it comes to science, I still see limits, where Deutsch sees only boundless opportunities. But Deutsch has persuaded me that we can solve many of our problems--especially self-inflicted ones like injustice, poverty, environmental degradation and above all war--as long as we don’t fatalistically accept them as inevitable. If the choice is between optimism and pessimism, why not choose hope?
Further Reading (and viewing):
See my 2011 video chat with Deutsch for Bloggingheads.tv; my 2018 Q&A with him for Scientific American; and a follow-up column in which I suggest that Deutsch’s belief in science’s infinitude “reflects wishful thinking rather than hardheaded realism.”
Multiverses Are Pseudoscientific Bullshit
Conservation of Ignorance: A New Law of Nature
My Controversial Diatribe Against “Skeptics”
The Ironic Interpretation of Quantum Mechanics
My Quantum Experiment (free online book)