Descartes argument for dualism • I can clearly and distinctly conceive of the mind without the body and the body without the mind • If I can clearly and distinctly understand two things as distinct they really are distinct. • Therefore the mind and body are two distinct things.
The mind is characterized by one sort of property, thought • Physical things are characterized by another sort of property, extension. • Two different kinds of things understood in terms of two radically different kinds of properties
The Mind Body Problem • If mind and body are really share no properties in common, then it is impossible for them to interact. • But mind and body do interact • Therefore Descartes’ substance dualism is false
Another mind/body problem • It is a law of nature that matter and energy can be neither created or destroyed • But if the mind causally interacts with the body, there is some new energy that comes into existence when the mind causes the brain to be in a certain state • So interactionist dualism violates a fundamental principle of science
Substance and property dualism • Substance dualism: two different things, mind and body • Property dualism: Only one kind of thing, but human beings and animals have certain properties that are not physical—mental properties
Kinds of property dualism • Epiphenomenalism: mental properties are byproducts of the physical body. They are caused by brain processes, but do not cause physical states. Its like smoke coming out of a locomotive engine. • Interactive property dualism: mental properties do have causal effects on the brain
Emergence and non-reducibility • Property dualism holds that mental properties are emergent properties • When organisms reach a certain degree of complexity, they get mental properties • Property dualism also holds that mental properties are non-reducible. You cannot understand the nature of mental properties by appealing to physical properties
Examples of Emergence • Biological properties are emergent on chemical properties. Being solid is emergent on the properties of lots of of molecules and their interactions, same with being colored. • But each of these are reducible. You can understand, for example, how a living cell works in terms of the chemical processes in that cell.
Do mental properties have to be emergent? • Churchland: mental properties could be like electromagnetic properties. A different part of nature not reducible to others. • But electromagnetism is displayed on all levels of reality, mental properties are only in complex organisms. • How do we know this?
Panpsychism • A property dualism might insist there are mental properties all the way down. • This would make the emergence of conscious beings more comprehensible • But it would also involve the belief that mental properties exist in so-called inanimate things.
The introspective argument for dualism • Descartes held that because thinking, reasoning, mental processes seem to be distinct from physical states, they really are. • Churchland argues that this may not be so. Colors don’t seem to be a matrix of molecules reflecting light, warmth does not feel like molecules vibrating.