After we came out of the church, we stood talking for some time together of Bishop Berkeley’ ingenious sophistry to prove the nonexistence of matter, and that everything in the universe is merely ideal. I observed, that though we are satisfied his doctrine is not true, it is impossible to refute it. I never shall forget the alacrity with which Johnson answered, striking his foot with mighty force against a large stone, till he rebounded from it – ‘I refute it thus.’
James Boswell: The Life of Samuel Johnson

Kastrup’s book is not for easy reading. Each sentence must be mentally uncompressed like a zip file. You really need to have a few concepts from philosophy at the ready. However, when you persevere, his reasoning proves crystal clear and it is not easy to find fault. I think it is worth discussing his arguments here because they are surprisingly close to my idea of the world and to my interpretation of the message of quantum physics. At the end of my book I arrive at the same view of the world as Kastrup. I champion the idea there of ​​a cosmic consciousness that ‘dreams’ this universe with us as actors in it, just like we can dream complete worlds in our sleep that are usually experienced as ‘real’ when in the dream state. Comparing Kastrup’s book with mine, in my book I do slowly peel away all the layers of the way we were taught that reality is put together, eventually arriving at Idealism. Kastrup however, goes straight to the heart of the matter – Idealism – starts from that position and then argues why that is a better and more fruitful view of reality than Physicalism.
The idea of a dreaming cosmic consciousness is essentially identical to Bishop Berkeley’s Idealism. Kastrup argues that Idealism provides the best explanation, needing the fewest ontological assumptions, for a large number of phenomena for which Physicalism is unable to provide any explanation. There are also various phenomena that even contradict Physicalism.
Any interpretation of the world, both Idealism and Physicalism, is ultimately based on a number of unprovable metaphysical assumptions. The less assumptions, the better seems to be a good starting point for a sensible choice between the two. Let’s take a look at the pros and cons for both systems and immediately register whether we can somehow be sure whether the premise is correct or not and whether it is consistent with experimental findings.
Physicalism, the problems
According to Physicalism, the world exists objectively and permanently. There exists only matter. Everything has ultimately a material cause. Our consciousness has to be a product of matter, an emergent epiphenomenon. But how can we actually justify that view with hard evidence? Remember that, without exception, the world presents itself to us as experiences appearing in our consciousness. Only at the exact moment they appear in our consciousness, those experiences become real to us. Experiences that appear in our consciousness are the only phenomena where we can unequivocally say that they are real. However, we can in no way assure ourselves that the source of our experience existed objectively and physically before it appeared in our consciousness as experience.
Samuel Johnson’s experience of his foot hitting the large stone is an experience within his consciousness. Not outside. So, it proves nothing. The fact that we agree with other people that something occurs in the world seems an argument for its objective physical existence but that is ultimately also an experience within our consciousness and thus cannot prove its objective existence. In a dream someone in your dream can confirm that he also sees what you see. But his confirmation turns out to be empty when you wake up.
Physicalism and quantum physics
Physicalism , according to its material premise, has to assume logically that consciousness is a product of matter because there is only matter. An emergent phenomenon of neural activity. However, consciousness as an emergent phenomenon of the brain does not explain the puzzling discovery of quantum physicists that observation does influence the outcome of observation. Even back in time. This is the logically inescapable conclusion of the so-called delayed-choice experiments, such as those by Scarcelli, Zhou, and Shih in 2007. For a detailed description of their experiment and the logical conclusions, I refer to my book, Chapter 7, Delayed Choice Quantum Eraser – 2007 version.
A universe with only matter offers no explanation whatsoever for the fact that the detection of the slit that was passed, has an effect back in time. That is because the ultimate cause of the disappearance of interference – the manifestation of the photon in one of the slits – must have occurred before the moment of detection of the slit passage.

And that is by no means the only experiment where Physicalism is incapable of explaining. All Bell experiments to date have shown with increasing confidence that the measurement on particle A – although the location of that measurement is still far removed from the location of the measurement on particle B – fixates the result of the measurement on particle B. That happens before the measurement on particle A the state of neither A nor B existed. You cannot claim seriously that the particles existed already, however without their properties. Therefore I speak deliberately of measurements and not of particles flying apart, since we cannot speak of a propertyless existence of a particle before the measurement. Something that exists has by definition properties, right? Physicalism does not offer a solution.
On top of that, the quantum collapse, the appearance in the measuring instrument of the particle that immediately before the measurement existed as a coherent probability wave is still an unsolved mystery for which a really fundamental explanation has not yet been found by Physicalistic theories. Quantum decoherence offers no real explanation for the quantum collapse but offers on closer inspection just another label for this phenomenon. It explains nothing. It also does not explain how a non-physical probability wave remains coherent. Coherence – coherence – is a phenomenon that is pre-eminently explained physically. How probabilities – numbers – can form a coherent wave is still not explained.
Physicalism also involves non-contextuality. This means that the outcome of an observation should not depend on the way in which other observations are made at the same time. Non-contextuality is contradicted by the Bell experiments too. An experiment to examine non-contextuality was conducted in 2019, the provisional result of which again appears to have violated non-contextuality. For more on this I refer to my post: ‘The consensus problem in quantum physics‘.
Apart from those physical experiments, there are countless phenomena in the world that cannot be explained properly or not at all with Physicalism. These are therefore often considered impossible and written off on the basis of fantasy, illusion, deception, faulty research, anecdotal evidence and what more. The near-death experience (NDE) is a good example of this way of ignoring evidence. Incidentally, The NDE can be perfectly explained with Idealism, in fact, it predicts it.
The objections to Idealism
Idealism says this: there is only a universal consciousness in which reality as we experience it takes place in the same way as when we dream. Obviously within consciousness. The materiality and permanence of the perceived world is an illusion. Kastrup lists the main objections:
- The experienced concreteness of the world.
- The personal private character of consciousness.
- Does only perceived reality exist?
- My consciousness is incapable of adjusting the perceived reality.
- If the world is a dream how come we share it?
- What is the origin of the laws of nature?
- That phenomena take place outside our personal psyche is equally well explained by Physicalism. Why another explanation?
- How is it that what goes on in our psyche correlates with the observable processes in our brain?
- Why is it that, shortly before we make a decision, brain activity already increases? (Libet)
- Where is that immaterial consciousness when we are unconscious?
- Isn’t Idealism the same as solipsism?
- How did the Big Bang come about without consciousness?
- When I look at the universe, I see no consciousness there.
It will go too far here to go into all these objections. I refer to Kastrup’s book, part III: Refuting objections. But I will go here into objections 1 to 4:
- The concreteness of the world is also ultimately an experience within consciousness. A good definition of consciousness is ‘That which experiences’. By that definition, there is no way to experience the objective world without the involvement of consciousness.
- That we all experience a personal private consciousness is completely possible if every private consciousness is an independently functioning part (subroutine) of the universal consciousness, but which can only communicate with that universal consciousness to a very limited extent.
- A technical example: Virtual computers within computers. The virtual computer has no direct connection to the hardware and cannot control it directly. I myself have a fully functional — and legal — Windows 10 running in a virtual environment on an Apple computer.
- A human example: Dissociative Identity Disorder (DID – formerly MPS). Several personalities can reside in one person. An excellent example is the case of a woman who has both blind and sighted personalities. When the blind personality takes control, the visual brain centers are demonstrably no longer active. They become active when a non-blind personality takes control. Read: Sight and blindness in the same person: Gating in the visual system.
- That the moon only exists when I look at it, that’s impossible, it cannot be! However, what do we mean by “the moon exists”? When I look at the moon, I see it because a number of photons manifest themselves on my retina. Those are not the identical photons that someone else sees. The other person who notices with me that the moon is in the sky receives his own photons, not mine. The moment that seeing the moon is needed within my experiences, the universal consciousness will ensure that I receive the correct photons according to the image of the world that universal consciousness is constantly creating and according to patterns that we recognize as laws of nature. Think of VR glasses, if I put them on and look around (move my head) the VR projects the corresponding image. The image that corresponds to what should be behind me is not projected into the glasses yet, it does not ‘exist’ yet.
- If consciousness creates the world, why can’t my thoughts create the world the way I want? The simplest answer to that is that I – what I currently experience as I – am a split off part of the universal consciousness. So I’m a case of DID. That split fragment that I am is incapable of influencing the total picture of the world with an action of the will. That is shielded from my mind. Incidentally, it has been shown in countless parapsychological experiments that the mind of the observer influences reality. Also think of what is often reported when people are dreaming and start realising that they are dreaming but are not able to alter their dream very much. Still a dream is viewed as something that is created by individual consciousness.
For the other objections against Idealism I have to refer to Kastrup’s book. I can tell you that he convincingly deals with all of them.
Idealism versus Physicalism
Idealism makes metaphysical unprovable assumptions. You cannot avoid that. According to Kastrup:
- Universal consciousness is primary. It is the ground of everything.
- Universal consciousness must have the capability of self-excitation, like a string that spontaneously enters a state of vibration.
- This self-excitation must be the source of every experience.
Defenders of Physicalism often point out – in the spirit of Samuel Johnson – that Physicalism does not require any metaphysical assumptions. Everything is already available. But this is not true. Where do the physical laws come from? Why does matter behave according to mathematical laws?
Quantum physics phenomena are explained by physicalists with the assumption of the quantum field. That is a field of potential that pervades the entire universe, constantly active at every point with virtual particles appearing out of nowhere and quickly disappearing into nothingness again unless it transforms – unpredictably – into a non-virtual – observable – particle.
- The quantum field is primary, it is the ground of everything.
- The quantum field has the capability of self-excitation. It continuously produces spontaneously virtual particles that are able to become objectively real.
- That self-excitation is the source of every observation.
When you compare quantum physics with Kastrup’s idealism, what would be the most parsimonious hypothesis in this, thinking of the phenomena which Physicalism cannot explain?
Nothing but benefits
If you consider it for a moment, Idealism appears to offer excellent explanations for a number of phenomena where Physicalism goes astray:
- The NDE
- The surprising aptitude of mathematics to describe the phenomena in the world while mathematics is pre-eminently a product of the mind.
- The fact that space and time depend on the position of the observer. That space can be curved. This indicates that space and time are a product of the mind.
- Synchronicity. Events that have no causal connection but have a common meaning for the person experiencing the synchronicity. Stopping clocks at the time of a family member’s death is one that happens quite often.
- The surprising precision with which the physical constants are aligned so that life is possible. A slight deviation from that would result in a universe without any life as we know it.
- The quantum coherence in living systems that persists much longer than is thought possible.
- The quantum efficiency of metabolic processes.
- Etc.
And last but not least. Idealism also offers a significantly more hopeful message than Physicalism. The end of the physical body is not the end of consciousness. The universe is far from meaningless.