Donald D. Hoffman, a psychologist at the University of California, Irving, has been getting a lot of attention recently for his views, that evolutionary evidence indicates that reality is an illusion, that the only thing that exists are conscious minds.
This is a modern version of an ancient concept, called idealism. The earliest writings about it come from the ancient Greeks, although they were almost certainly influenced by the Indian ascetics and sages.
Hoffman’s version is built using ideas of modern science. He starts with the observation that we aren’t evolved to perceive reality as it is, but in a way that is adaptive, that ensures our survival. He then brings in quantum physics, noting the often held understanding that consciousness is what causes quantum decoherence (aka wave function collapses). From this, he deduces that the external world is an illusion, that conscious minds are all that exist. (This is admittedly a very quick and dirty summation. Read the articles for a more thorough, and perhaps fairer summary, or watch one of his talks or debates.)
Hoffman has a very valid point about our minds not being evolved to accurately comprehend reality. This is something that has been understood for a long time. The idea that we can’t naively trust our perceptions is ancient, and has been well known throughout the history of modern science. (For example, see Francis Bacon’s Idols of the Mind.) Reality is not as we perceive it, although it’s a large jump from that common understanding to concluding that reality overall is an illusion.
To bridge that gap, Hoffman brings in quantum physics. To be clear, quantum physics is bizarre. The more people seem to understand it, the more bizarre it seems to them. However, Hoffman’s understanding of consciousness causing quantum decoherence might be a bit dated.
Quantum decoherence is now commonly described by physicists to happen from any interaction with the environment. Only isolated quantum objects, such as individual subatomic particles before they interact with anything (such as hitting the screen in the double-slit experiment), or molecules kept in very isolated laboratory conditions, can remain in a superposition wave state. In other words, Schrodinger’s Cat either lived or died before the box was opened, since a cat is definitely a noisy system in terms of quantum interference.
This makes sense when you consider why scientists and engineers are struggling to build quantum computers. Keeping qubits, quantum computing’s version of binary bits, in superposition, preventing them from decohering, is a major challenge. It’s also why most proto-quantum processors have to operate at near absolute zero temperature, to avoid disturbing the superposition state of the processor’s internals. If preventing conscious interaction were all that were necessary to prevent decoherence, it seems like these designs could be much simpler.
There’s also the broader difficulty that using sensory experience to conclude that all sensory experience is an illusion, that is, using data from that illusion to conclude it is an illusion, seems problematic. Of course, someone could say they find logical contradictions or absurdity in that data, hence the illusion conclusion. But then I have to ask, contradicting what? Or absurd by what standard?
But, just for the sake of argument, let’s bracket those difficulties, and assume Hoffman is right. Idealism is true. One of the other issues I’ve always seen with idealism is that it exempts other minds from this logic. If everything else is an illusion, what prevents any other minds I perceive to be out there from also being an illusion? Maybe I’m the only mind that exists. Or maybe you are and I’m the illusion. Of course, this is solipsism. But I’ve never been able to see what stops idealism from being a logical slippery slope into solipsism.
Furthermore, if we’re going to engage in this kind of skepticism, we can’t even be sure about our own memories. Maybe everything outside of your mind is an illusion. Maybe you came into existence 30 seconds ago together with your existing memories. Perhaps you are in fact a Boltzmann brain, a conscious entity that emerged from random fluctuations a few seconds ago, and will disappear back into those fluctuations in a few more seconds.
All of this is aside from the issue that if reality is an illusion, that illusion appears to exact unpleasant, often painful consequences for not taking it seriously, including consequences for aspects of that illusion we don’t know about, or forget about, or any of the other problems caused by what we normally think of as objective, mind independent reality.
Essentially this makes the illusion our reality, our universe. And that all the people who insist that there is a reality outside of the universe are right. We can only hope, if anyone is controlling this illusion, that they’re kindly disposed toward us, or at least not hostile. The border between this line of reasoning and theology seems like a blurry one.
All of which is to say, if reality is an illusion, then we have little choice but to play the game. It makes sense to play that game as well as we can, which means understanding it in the most reliable way we can, which brings us back to the methods of science and philosophy for understanding what we commonly call objective reality.
Unless, of course, I have logical holes in my reasoning.