Mind-body dualism – The body is material and governed by physical law; the mind immaterial and not governed by physical law. Reality is dual, composed of both physical and mental facts. According to Descartes, persons have privileged access to their mental states, and they are infallible with respect to those states.
Objections to dualism – 1) How do non-physical things interact with physical things, inasmuch as they are completely different kinds of things? 2) The idea of a non-material substance makes no sense; 3) It seems impossible for dualism to explain how immaterial mind emerged in the first place, given that reality started completely material.
Materialistic theories of mind – There is nothing ghostly or non-physical within us; the physical explains the mental.
1) Behaviorism – Behaviors explain mental events. Jane didn’t shout because she was angry, rather Jane shouted because of some stimulus. Gilbert Ryle took this one step further and eliminated mental events altogether. We don’t have to explain immaterial substances or how they interact with matter because there are no immaterial substances.
Problem with behaviorism – 1) Mental states seem to exist without corresponding behaviors. 2) Not all mental states correspond to behaviors. (What behavior corresponds to listening to Mozart?) 3) Different mental states can correspond to identical behaviors.
2) Mind-brain identity theory – Brain events cause mental events. Science confirms that brain physiology causes mental events. Mental events and states are neurological. This explains: a) mental facts without positing souls; b) how mind and body are connected; c) thought without necessary reference to behavior, and d) introspection.
Problems with identity theory – If mental states are brain states, then things without brains (aliens, robots) couldn’t feel, for example, pain or joy. But couldn’t robots without brains feel pain if they were wired to feel pain? This thinking leads to another theory:
3) Functionalism – mental states (like pain) are equivalent to whatever physical system (cells, wires, chips, etc.) serves the function of creating experiences. For us, pain is neurons firing to link input with output, for aliens or robots, this might have to do with different biological or mechanical wiring. So functionalism is an advanced theoretical version of mind brain identity to account for robots, aliens, etc.
Problem with functionalism – Wires or chips can’t be the basis of consciousness, and robots without brains wouldn’t be conscious even if they acted conscious.
Basic objections to any materialist theory of mind
Having subjective experiences is the “what it is like” to have a mind. But how does a brain state equal a taste, feel or smell? [Philosophers refer to these states as “qualia.”] The idea is that neuron firings are objective while brain states are subjective. This is the biggest problem for materialistic theories of mind.
This problem is related to another problem for materialistic theories of mind—the problem of intentionality. Intentionality is the idea that mental states are about things. But how are neurons in brains about things? We might explain this by saying that brains resembles colors or smells, but this doesn’t seem right. Brains may be about smells or colors, but colors or smells aren’t about brains. Now we could say that brain states resemble mental states, but they don’t. If we look at your brain when you see green trees we won’t see green brains! And if we think about an abstract idea like the square root of -1, there is no physical thing that could look like that. So it doesn’t seem that resemblance between brains and minds explains how brains give rise to minds.
So perhaps we shouldn’t draw any conclusions about the philosophy of mind and the mind-body problem, since there is so much we don’t know about neurophysiology. Yet we are learning all the time and most neurobiologists think the brain will eventually be explained in full. For the moment though, we might take Wittgenstein’s advice: What we cannot speak of we must pass over in silence.
(This entry relied heavily on James and Stuart Rachels’ book: Problems from Philosophy.)