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The question of dualism
Plato started it, 400 years BCE. He drove a wedge between mind and matter, claiming that human souls move between two worlds: a world of immaterial ideas, and a world of material, physical appearances. When a person is born, a soul temporarily moves from the world of ideas to the physical world, and nestles in the newly-born human body. This soul stays there until the physical body expires, at which point it returns to its non-physical home. Not only human souls, but the essence of each and every physical object, resides in a separate world of ideas. How else can we explain that we have certain ideas in our minds – abstract ideas like justice or beauty, concepts of geometry, ideas of a supreme being – ideas which we cannot have acquired from perception of the physical world. We only perceive particular instances of these abstract ideas, never the ideas themselves. Sure, we must have been born with these innate ideas, and accessing them is simply a matter of remembering them …
This dualism of mind and matter feels very familiar to most of us, because for 2000 years all the main religions in the world have made it the pinnacle of their teachings.
René Descartes ( † 1650 ) is the father of modern-day dualism in Western philosophy. In reply to his own question “What can I know for certain, without any doubt?” he postulated a dualist answer. First, the only thing I can be absolutely certain of, is that I am a thinking being. I know for myself that as I sit here, my mind is at work. I have direct access to my thoughts, so while I may not be sure whether anyone else is thinking (I have no access to their thoughts), I do know that I am thinking. Cogito Ergo Sum, I think therefore I am. I may be mistaken or deceived in what I think, but the very fact that I think or am being deceived, requires a thinking being, a mind. This then, for Descartes, proves that there is a mind. For the second part of his answer, Descartes takes a bit of a leap – literally, a leap from the inside of his own mind into the external physical world. At first, he realises that this leap deceives him from time to time. Some of the information his mind receives from the external world, turns out to be false, or at least not readily available. If he is deceived once, or twice, why not all the time? If he’s deceived all the time, isn’t there reason to believe that there isn’t actually an external world at all? Maybe it’s all an illusion. “No. Because there is a benevolent God,” is Descartes’ reply. In His benevolence, He has given us special languages to interpret facts about the world that we can trust, that are indubitably true – logic and mathematics. Whenever we stick to these languages, we can trust that we are perceiving truth. This proves for Descartes that there is another world, outside and independent of our minds: the physical world.
Mind and matter are fundamentally different. The physical world is made up of substances and properties that are very different from those that make up the mental world. Matter is extended – located in space and time – and governed by a closed system of physical causal laws. We only find spatial dimensions in the physical world. Mind is not extended – an idea does not weigh anything, and doesn’t take up space or time – and is governed by logical laws of rationality.
It would seem that most of us intuitively agree with Descartes. Of course, human thought and consciousness are of a different class, a different level, than the physical world. But are they really? Perhaps we have simply not yet been able to explain mind in physical terms. Perhaps it’s just a matter of time for science to come up with a physical explanation of brain structures and processes, which will explain mental phenomena and reduce them to the physical phenomena they rely on.
One problem for the dualist, sounds like this. If mind and matter really are so fundamentally different, if they really are defined by fundamentally different properties, how are they able to interact? How does mind causally affect matter, and vice versa? How can a thought to move my arm, cause my arm to move? If mind is not matter, then what is it? Some speak of souls, others of energy, consciousness and emergence. But what do they all mean?
These questions, this inability to grasp mind and consciousness, has driven philosophers to three possible conclusions. Either mind and matter are totally different, separate. That’s the dualist point of view. It fails to explain mind in physical terms, but has no intention whatsoever to do so, because minds operate in a world of their own – whether or not we can explain that world. Or mind is simply matter and nothing else. In other words, we can only explain the mind from a physical perspective, because the physical perspective is all there is. The best way to explain mind, is by referring to the physical events that underly it. Happiness? A chemical brain reaction. Pain? A process in the nervous system. Prayer? Dopamine. Or mind exists, but not as a separate substance, but rather as a side-effect of matter, an afterthought, a ghost in the machine, an emerging property of matter. Mind is something separate, but cannot exist without the physics it relies on. And it most probably has no way of interacting with matter.
Can we reduce mental mind states to physical brain states? If we were able to reduce all mental states (e.g. happiness) to their physical counterparts (e.g. chemical reactions in the brain), is there anything that is essential to the human experience that we have not explained?
Yes, there is, claim some. Explaining the human experience in purely physical terms leaves something out – that which makes us uniquely human. For some this may be art, or morality, for others religion. Think of it this way. Science may reduce music to a sequential succession of audio waves in various degrees of length, pitch and volume, that trigger the human auditory system, which in turn causes neural pathways to fire and interact with other neurons and thereby create new or reinforce existing neural pathways and stimulate the exchange of dopamine, serotonin and whatnot, which then causes the heartbeat to increase, the pupils to enlarge and the mouth to salivate. But science has hereby not fully explained what humans experience when they hear music. Even though robots may be able to write and hear music, can their experience of writing and hearing music ever be the same as the rich, self-conscious, intellectually challenging and satisfying, emotionally evocative human music experience? One can easily apply this same question to seeing colours, tasting food and of course, love. Can these human experiences be scientifically reduced or programmed in physical, causal phenomena?
No there isn’t, others claim. Thinking that there is an experience separate from physical processes, is an illusion, a flawed attempt at explaining something we don’t (yet) understand. The history of human knowledge is defined by revealing these illusions, and replacing them by scientific explanations. Thunder is not created by a thunder god, but rather by a meteorological process – a process we now understand and can explain in the framework of the laws of nature. Mental illness is not a punishment from God, but an imbalance in neural mechanics. Falling in love is not a hit by Cupido’s arrow, but a well-orchestrated event in the chain of the species’ evolution and continuation. We should accept that our old explanations of the world were wrong, and that they have no place in our growing understanding of the physical world, including the physical workings of the human mind. Human behaviour is not a result of elusive, mental unicorns, but rather a physical reaction in a chain of physical events.
So, where does that leave us? Are our thoughts, passions, ethics, behaviour and characters really merely the result of a causal chain of physical events? Can we really explain all the mental states by their underlying physical brain states, caused by other physical phenomena? If we can’t, then how do we account for mental states without falling back onto unverifiable assumptions? If we can, what does this mean in terms of moral responsibility and free will? And what happens to poetry?
- Massimo Pigliucci, Consciousness is real, www.aeon.co
- Frank Jackson, Epiphenomenal Qualia (1982) in Philosophy of Mind, Classical and Contemporary Readings, David J. Chalmers (Oxford University Press, 2002)
- Paul M. Churchland, Eliminative Materialism and the Propositional Attitudes (1981) in Philosophy of Mind, Classical and Contemporary Readings, David J. Chalmers (Oxford University Press, 2002)
- René Descartes, Meditations on First Philosophy (1641) in Philosophy of Mind, Classical and Contemporary Readings, David J. Chalmers (Oxford University Press, 2002)