The Mind-Body Problem

The nature of consciousness is one of the most fundamental questions of human existence, if not the most fundamental one. What’s known as ‘the mind-body problem’ has intrigued and frustrated philosophers and scientists since the start of recorded history. Is the mind part of the body, or is the body part of the mind? Whilst we know that the body is made of organic matter, what about the mind? Is it made of different stuff? What is the mind? Questions, questions, questions.

As always the ancient Greeks had much to say about it: Plato took the view that the soul is separate from the body and is immortal (note: ‘soul’ and ‘mind’ are interchangable terms used by early philosophers). Plato came to this conclusion because he thought that things like ethics and mathematics couldn’t possibly come from the bodily senses and therefore ‘knowledge’ must be a separate entity. Aristotle, on the otherhand, believed that since the body is a part of nature then the mind must be as well. Function and form were key and Aristotle saw the mind as structured matter and not some spirit floating around in the ether. The only thing that Plato and Aristotle broadly agreed on was that our capacity for reasoning sets us apart from the other animals, and that the soul is a definite entity, immortal or otherwise, and consists of three tiers: appetite, perception and intellect. Talking of which, Plato famously wanted to throw poets out of the Greek Republic.

This ancient Greek take on the soul held sway for many centuries and was adopted by early Christianity. It was first seriously challenged by Rene Descartes, the 17th century French philosopher. Descartes believed that Greek metaphysics was a load of tosh and instead posited that there were two quite separate entities: ‘material substance’ and ‘thinking substance’. His seminal work was The Meditations, which is still required reading for anyone studying philosophy. Descartes begins by doubting everything; ie, what in your existence can you be sure of with certainty? Think about that. In The Meditations he comes to the conclusion that the only thing he can be certain of is his own mind; everything else, including the body, could be trickery or illusion/dreams (hence the famous quote: Je pense donc je suis, I think therefore I am). Descartes then asks himself the pertinent question: what is the mind? He came up with the ‘thinking substance’. Descartes was the first major philosopher to clearly differentiate the physical from the mental. If you like fancy lingo, Descartes’ mind-body separation is known as Cartesian Dualism.

Descartes was a scientist as well as a philosopher and as such he took theology out of the mind-body debate. However, this still left the intimate relationship between mind and body: how can something mental interact with something physical? How can an ethereal thought make your physical body do something? Now think to yourself: “I’m going to raise my arm”, and voila! up it goes. What’s going on there? This issue was addressed by Spinoza, a 17th century Dutch philosopher, who claimed that there was only one huge, determined substance in the Universe, and it could be seen as either a complete causual physical system or as a complete causual mental system. Confused..? You will be! Spinoza’s view was that a person consisted of a physical body and their mind was a correalate of all that physicality. In otherwords, ‘thought’ was not a separate entity but was embodied. This caused grave concerns for the Bible bashers of the day, whose main tenant was the soul and immortality and a place called Heaven. Spinoza was a theologian and his claim that the Universe is one entire thing, and you can call it either God or Nature, caused him to be expelled from the Jewish community in Holland. In later centuries philosophers like William James and Bertrand Russell still subscribed to Spinoza’s view, that existence comprised of just one kind of ‘stuff’, and instead of Descarte’s substance dualism it was more a case of property dualism; ie, the one kind of ‘stuff’ has two different properties, the physical and the mental. William Barclay also went along with the one kind of stuff view, although he believed that the substance was entirely mental. No wonder so many of these philosophers went mad.

Then we have epiphenomenalism (try saying that when you’re drunk), a theory put forth by Thomas Huxley, an admirer and contemporary of Charles Darwin. Huxley took on board three seemingly indisputable facts: we are entirely biological organisms, the physical world has causual closure (meaning that any effect in the physical world is caused by something else) and the organ of thought is the brain, a physical object. From this, Huxley deduced that whatever is going on in our minds is the product of a purely physical process going on in the brain. Huxley saw humans as a biological machine, and the thing we call ‘thought’ is the noise from that machine. The noise does not drive the machine; it is a byproduct of it, an epiphenomenom. Thus, when we go to do something the thoughts involved are not driving the action. We are doing the action anyway and the thoughts are a by-product of it. The hum from the machine. There is no real memory, belief, hope, desire or intention, etc. The conscious mind is an allusion. The American philosopher Jerry Fodor has said that if epiphenomenalism is true then it will mean the end of the world, in the sense that existence isn’t what we ‘think’ it is.

Epiphenomenalism is hard to disprove because of its very premise, and because of Huxley’s brutal logic. Many philosophers fudge the issue when trying to disprove it. John Searle, who’s done a lot of work on Philosophy of Mind, shows epiphenomenalism to be false by just raising his arm, saying that his thoughts made him do it. An epiphenomenalist would of course say that the thought is an illusion; noise from a complex machine. Ok, so let’s look at that machine, and in particular the nervous system: in the human body there is the central nervous system, consisting of the brain and spinal cord, and there is the peripheral nervous system, consisting of an autonomic system and a somatic system. The autonomic nervous system controls the involuntary actions of the muscles, heart and glands. It works on a subconscious level and keeps vital body functions going, as well as providing ‘instinctive’ reaction to danger (ie, if someone pretends to hit you you’ll blink). The somatic nervous system is responsible for senses and skeletal muscle control and thus is a driver of high level consciousness and can be associated with ‘thought’, what the epiphenomenalists call noise from the machine. Nature always keeps things as simple as possible, so why would we have a somatic system on top of an autonomic system if not to drive thought? The epiphenomenalists believe that we are completely autonomic.

Epiphenomenalists aside, the modern view is that the mind resides in the brain and central nervous system, but of course it’s still not known how mental phenomena arise or indeed what they are. Memory, belief, hope, desire, intention, none of these things can be explained mathematically. They seem to exist outside of the physical world. I believe that Spinoza came closest to cracking the nature of consciousness, with his one substance with two properties theory. Spinoza lived before the atom age and didn’t know that existence is comprised of atomic matter. This matter is now quite well understood in the macro world, the world of Newtonian physics. Much less understood is how this matter behaves in the micro world, the world of quantum mechanics. It’s all the same ‘stuff’ yet its properties are very, very different in the Newtonian world to what they are in quantum world.

How can something mental interact with something physical? How can an ‘ethereal’ thought make your physical body do something? It’s because both mind and body are made up of the same fundamental stuff, but this stuff has two spatial properties. The body resides in the Newtonian world, and it must be that the mind resides in the quantum world.

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