Descartes created the debate about mind-body dualism with his notion that the world has two fundamental constituents – physical substance and mental substance. Over the years, one of the principal objections to this has been that these are so different that you would need to explain how they could interact. Counter-proposals are usually called reductionism – the idea that one of these is fundamental and the other arises from it, or there is something more fundamental that produces both of them.
Berkeley, Hume, etc. advanced mental reductionism – all we know of the world comes through the senses so it is all mental phenomenon – it is our minds that create the impression of a physical world out there that is responsible. Hume also asserted that our idea of causation is similarly created – his example is a billiard ball hitting another one. You see one stop and one start, but you don’t see causation – you impose that on the experience.
Research on child development finds that the common viewpoints of a physical world governed by cause and effect are imprinted early. These are not theories concocted by a reasoning process, but kick in more or less automatically. That though does not mean they are true – just that they improve survivability. Maybe the real takeaway from all this skeptical philosophy is just that – we have these things more or less built in. They helped us survive as hunter-gatherers. But they are not necessarily fundamentally true. That attitude might help us cope with modern physics, where it is more of an approximation to wilder stories.
Berkeley took his theories further – since we don’t believe that things disappear when we’re not looking, their permanence is maintained by God always perceiving them. This led to this limerick, attributed to Monsignor Ronald Knox:
There was a young man who said “God
Must find it exceedingly odd
To think that the tree
Should continue to be
When there’s no one about in the quad.”
“Dear Sir: Your astonishment’s odd;
I am always about in the quad.
And that’s why the tree
Will continue to be
Since observed by, Yours faithfully, God.”
One of my philosophy professors at Berkeley, Benson Mates, was especially a scholar of the history of philosophy – with a famous paper on Stoic logic. He would often invoke what he called “the scholastic maxim:” when in doubt, make a distinction. Apparently he would also give his children puzzles in the theory of sense perception – like what color is the butter when the refrigerator door is closed and the light is off? One of his more controversial papers was “Berkeley Was Right.” He rebutted Samual Johnson’s alleged refutation of Berkeley – kicking a large stone that his foot did not pass through. But Mates said that Berkeley was jumping to conclusions on the God stuff. Still, mental reductionism makes it difficult to account for much of our daily experience, so it is not all that appealing.
On the other extreme is the far more common physical reductionism. Consciousness somehow arises out of physical processes in the brain. It’s always “somehow,” although science is advancing on that front. Consciousness seems to be associated with complex neural and electrical processes over regions of the brain. But philosophers are quick to note that association is not enough to explain how or why any experience is there. I like the idea that the brain is not creating consciousness but tuning it in. But more on that later.
Some analysts in this school go so far as to say that consciousness is an illusion. To me that is self-contradictory. You can’t have an illusion without having consciousness in the first place.
The Vedanta school of philosophy is closer to the something-else type of reductionism. All of the physical and experiential universe arises from a more fundamental base. What this might be is difficult to describe, so usually they just use the pronoun That. “I am That, Thou art That, all this is nothing but That.” “I” is my innermost self, “all this” is the material creation, and they throw in God for good measure. There is one thing that manifests into consciousness, the universe, and even God. All of these are fundamentally different expressions of that single essence.
Quantum field theory provides another possible avenue towards a something-else reductionism, or at least a more consistent dualism. It gives an explanation of underlying processes that can account for some puzzling aspects of the behavior of particles and light. The electron is a quintessential particle, and we know about waves of light. But light also displays particle-like behavior (photons), and electrons act like waves in some experiments. Also they are impossible to pin down exactly as to position, speed, and mass.
These facts can all be predicted by the equations of quantum theory. The math of it is waves moving around that can be used to calculate the probabilities of the location, speed, mass, etc. of the electrons and photons. The waves can interfere with each other as waves do, and that explains the wave-like behavior.
That all works out extremely well observationally, but it is difficult to interpret the math as any kind of physical process. Physics does a dodge at this point. It turns out that the purpose of physics is not to explain the nature of the world, just to predict observations. Science is actually a branch of engineering. The interpretation problem is not an easy one. The quantum waves make for complicated mathematics, which can be represented in an 8 or 10 dimensional space. And it is not clear what is waving. It’s not any physical thing we know about, like water, energy, or the essence of space-time, which is apparently what gravity waves propagate in. So many physicists are willing to just call it “the quantum field” and leave it otherwise unexplained.
One attempt some physicists do make at describing what is waving is to call it information. The information waves move about, interact, and always provide probabilities of observations. This viewpoint incorporates what these waves provide, and reflects how little they have to do with any physical substance. The term “information” is used a lot in physics, and so far I am not convinced that all the uses are consistent, but maybe they are.
If information is indeed the essence of the physical world, then it should be accessible by mental substance. That is, the original interaction problem of dualism becomes less intractable. But could the field of information also be the basis of consciousness? That at least provides a way to explain how complex neural-electric processes in the brain could access consciousness. While this is no proof, at least this approach avoids the problem that physical reductionism has with creating consciousness out of physical processes, as well as the generally unsatisfying nature of mental reductionism.
Both mental and physical reductionism have religious aspects to them. Some people really want to believe in the fundamental reality of the physical world, and so adopt the “somehow” explanation for consciousness. The dodge that physics makes to avoid discussing any interpretations of quantum theory allows them to maintain this point of view unquestioningly. But they then have no physcial view of the nature of fundamental particles. They are represented mathematically as fuzzy blobs of some sort, not made of any physical substance, but they can ignore that as not a physical issue. The dodge allows them to maintain their faith.