2The optionsThe mind is not the brain: it is a different thing, i.e. it can exist on its own without the brain (e.g. after death). (Substance dualism)The mind is the brain: they are completely identical. (Materialism/physicalism)The mind depends on the brain to exist: mental properties are properties of the brain, but they are not physical properties. (Property dualism)
3Substances and properties Substances can have different sorts of propertiesReductive physicalism: mental properties are physical propertiesProperty dualism: mental properties are not physical propertiesHmm…
4Arguments for substance dualism Religious teachingsDifferent essential propertiesDescartes: The body essentially has parts, the mind has no parts. So they are different kinds of thing.Descartes’ argument from knowledge
5Descartes’ argument What am I? I am a thing that thinks. I cannot doubt this, yet I can doubt whether I have a body.So I can be separated from a body.
6ObjectionJust because Descartes can think of his mind existing without his body, this doesn’t mean that his mind really can exist without his body.Cp. I think the Masked Man robbed the bank; I don’t think my father robbed the bank; Therefore, my father isn’t the Masked Man.If ‘two’ things have different properties, then they really are distinct. But we can be mistaken about the properties of things.Perhaps there is a metaphysical connection between mind and body that Descartes doesn’t know about.
7Parts and propertiesThe argument that mind has parts assumes that minds exist as things that have properties.Materialists reject this – minds don’t exist, only mental properties (of brains) do.
8The challenge of mental causation Descartes: mind and body are different kinds of thing. The mind is just thought, not in space; the body, matter, is just extension, in space.So how could one possibly causally affect the other?All physical effects have a sufficient physical cause. Nothing physical happens needs a non-physical explanation.Mental causes would violate the laws of physics, e.g. law of conservation of energy.
9Mind-brain identityOntological reduction: the things in one domain (e.g. mental things) are identical with some of the things in another domain.Reduction: this makes the ‘reduced’ domain more intelligibleIf mind = brain, then mental causation doesn’t violate of laws of physics and we can understand how it happens (usual physical way).
10Jackson’s knowledge argument Mary, a neuroscientist, has never seen colour, but knows all about colour perceptionMary doesn’t know what it is like to see red - so, although Mary knows all the physical facts about seeing red, there is a fact (of consciousness) Mary doesn’t knowTherefore, properties of consciousness are not physical properties
11ReplyMary doesn’t learn a new fact, but a new way of thinking about an old fact. She now knows the fact of what happens in the brain through introspection.On concepts and properties: the same fact (the glass contains water) can be thought of in different ways (the glass contains H2O).