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Frank Visser, graduated as a psychologist of culture and religion, founded IntegralWorld in 1997. He worked as production manager for various publishing houses and as service manager for various internet companies and lives in Amsterdam. Books: Ken Wilber: Thought as Passion (SUNY, 2003), and The Corona Conspiracy: Combatting Disinformation about the Coronavirus (Kindle, 2020).

Is Bernardo Kastrup Bonkers?

When Idealism Calls Materialism "Baloney"

Frank Visser / ChatGPT

When philosopher Bernardo Kastrup declared in an essay that "materialism is baloney," he likely expected strong pushback. But perhaps he didn't expect to be labeled "bonkers" in return—at least not by a sober-minded naturalist like myself.[1] The phrase, meant somewhat tongue-in-cheek, points not to Kastrup's intelligence—which is considerable—but to the epistemological audacity of his project. If materialism is dismissed as irrational folly, why should we treat his idealism with more respect?

This essay takes a critical look at Kastrup's brand of analytic idealism, not to ridicule it, but to show how it falls into the very speculative traps it accuses materialism of perpetuating. If I occasionally adopt a provocative tone, it's to match Kastrup's own—for when one calls centuries of scientific inquiry "baloney," one should expect a few rhetorical punches in return.

THE PROVOCATION: "MATERIALISM IS BALONEY"

Bernardo Kastrup is among the most eloquent defenders of idealism today. His version of it holds that consciousness is the only ontological primitive, and that everything else—spacetime, matter, energy—emerges from mental processes or mental appearances. He claims this is not mysticism but reasoned metaphysics, consistent with modern physics and the findings of analytic philosophy of mind.

But Kastrup doesn't just advocate idealism—he wages war on materialism. In book after book, essay after essay, he describes the materialist worldview as not only false but "incoherent," "absurd," and yes, "baloney." He sees materialism as a conceptual relic: a clumsy leftover of Enlightenment rationalism, unsupported by empirical science and rife with internal contradictions.

This polemic tone is seductive to many who are weary of reductive neuroscience or scientistic dogma. But it also invites a fair question: Does idealism really offer a more coherent alternative?

THE RETORT: "IDEALISM IS BONKERS"

Calling idealism "bonkers" may seem like a low blow—but I use the term advisedly, and in response to Kastrup's own provocations. By this I mean: his philosophy, while intellectually stimulating, displays a cavalier disregard for empirical science, an overconfident metaphysical tone, and a tendency to repackage ancient spiritual tropes in analytic wrapping paper.

Let's consider the core issues:

1. Reversal of the Scientific Epistemic Order

Materialism, or more broadly physicalism, begins with what science can observe and test: matter, energy, laws of nature. Consciousness is admittedly a puzzle—the so-called "hard problem"—but it's not solved by declaring the physical world to be illusory. Kastrup flips the entire ontology, declaring mind as the only reality and the physical as a dream or simulation in consciousness.

This is not a “parsimonious” move, as he claims. It's a metaphysical leap: one that leaves us with no clear link between subjective experience and the apparent order of nature, except vague analogies like “dissociated alters” of a universal mind. Such claims may sound elegant, but they rest on conceptual speculation, not experimental validation.

2. Conflation of Metaphysics with Science

Kastrup frequently cites quantum physics, cognitive science, and neuroscience as evidence for idealism. But his interpretations of these domains are highly selective and controversial. Most physicists do not endorse idealist metaphysics. Most neuroscientists proceed on the assumption that brain processes give rise to consciousness, not vice versa.

While Kastrup is skilled at weaving scientific references into his narrative, he routinely overstates the philosophical implications of scientific findings—especially those related to quantum indeterminacy or observer effects. This is a classic move in post-materialist metaphysics: to use physics as a launching pad for metaphysical speculation, while ignoring its methodological boundaries.

3. Dismissal of Materialism without Due Diligence

Materialism, for all its philosophical challenges, delivers the goods. It underlies modern medicine, technology, evolutionary biology, and neuroscience. It provides a working model of reality, even if incomplete. Kastrup dismisses it as incoherent but rarely acknowledges its explanatory power or historical success.

In this, his critique resembles that of many spiritual or metaphysical thinkers who, frustrated with the explanatory limits of science, declare the entire paradigm obsolete, rather than engaging with its internal evolution. This is not a revolution—it is a regression, back to an enchanted cosmos where mind precedes matter and where metaphysics trumps empirical inquiry.

4. Philosophical Overreach in the Name of Simplicity

Kastrup often appeals to Occam's Razor, arguing that idealism is simpler because it posits only one substance: mind. But simplicity is not the only criterion for truth. Coherence with observation, predictive power, and resistance to falsification also matter. Kastrup's system explains everything—and therefore risks explaining nothing. If all things are mental, how do we distinguish hallucination from physics, dream from fact, soul from synapse?

His metaphysics is elegant, but unfalsifiable—and in this, it mirrors the very dogmatism he accuses materialism of.

WHY IT MATTERS

This debate is more than academic. Idealism is gaining popularity in circles that are disenchanted with reductionism, drawn to consciousness studies, or steeped in Eastern philosophy. Kastrup provides an articulate framework for this turn—but one that risks undermining the methodological humility that has defined modern science.

In the end, calling idealism "bonkers" is a way to reclaim the value of epistemic modesty. It's not that Kastrup is irrational—he is deeply rational within his premises. But those premises themselves are metaphysical indulgences, not empirically compelled conclusions. And when he calls materialism "baloney," he opens the door to strong rhetorical pushback—not to silence him, but to balance the discourse.

CONCLUSION: A CALL FOR INTEGRITY IN INQUIRY

Bernardo Kastrup is not a charlatan. He is a passionate metaphysician with a coherent worldview. But in dismissing materialism so brashly, he invites the same scrutiny for his own system. And from the standpoint of empirical science and philosophical naturalism, his vision, for all its beauty, is epistemically extravagant.

So is he bonkers? Not in the clinical sense—but in the metaphysical one, perhaps. For when one trades the hard-won clarity of science for the poetic unity of cosmic mind, one risks mistaking metaphor for ontology.

And in that sense, we must tread carefully. Not everything that sounds profound is true—and not everything that is true sounds profound.

NOTES

[1] See my 3-part series on Bernardo Kastrup, which I wrote after I had some unsuccessful exchanges with him on his website forum:

• Part One: Why Idealism is Bonkers, Some Reflections on the Philosophy of Bernardo Kastrup, November 2019
• Part Two: 'Why the Tree Will Continue to Be', Further Musings on the Idealism of Bernardo Kastrup, November 2019
• Part Three: 'We don't know whether mutations are really random or not', Reflections on Randomness by Bernardo Kastrup, December 2019