Paul Churchland on Dualism in Matter and Consciousness

Varieties of Dualism:

I.  Substance Dualism

A. Cartesian dualism
matter:  extended in space (and does not think)
mind-stuff:  thinks (and is not extended)

person = 1 body (matter) + 1 mind (mind-stuff) in causal interaction

two initial worries about this view:  (1) if mind-stuff has no mass, shape, or location, how does it get the body to do things?  (2) anyway, the essential feature of matter does not seem to be extension in space.
 

B. Popular dualism
minds have no mass (or shape?) but do have location:  inside a body

II. Property Dualism

There is only one sort of substance, but it has both physical and nonphysical properties

(nonphysical = cannot be reduced to or explained in terms of physical properties)

[Bracketed comments are mine -- CB:  One way to think about this is to think of mental properties, on the property dualist account, as extra properties in some sense.  For instance, imagine what it would be like if color turned out to be an extra property.  It could be that only certain kinds of objects have colors, but it could have turned out that color had no relation to microphysical properties -- that color could differ even between physical duplicates.

there are many properties which it is not straightforward to define in terms of physical properties, but which we nevertheless do not think are extra in this sense: e.g. smiling, being worth $3, being alive, being yellow, being a chair. The property dualist thinks that mental properties are extra in a sense in which these are not.]

A. Epiphenomenalist property dualism

mental properties are caused by physical properties, but have no causal effects in turn (the mental as superfluous)

reason for the view:  (a) firm conviction that mental properties are irreducible to physical ones, with (b) firm conviction that physical causes suffice to cause physical behavior.  If both (a) and (b) are held to, epiphenomenalism is the only option

but notice how persuasive (b) is: to invoke nonphysical properties seems to be a way of giving up the search for an explanation.

B. Interactionist property dualism

mental and physical properties interact causally

mental properties are (a) emergent and (b) irreducible.
But these two features fit oddly together; seems it would be better to give up one.
If you give up (a), you are a panpsychist; if you give up (b), you are a materialist.

Arguments for Dualism (and Responses)

1. argument from religion

responses:
(1) historically, attempts to decide scientific questions on religious grounds have been a disaster
(2) religious belief is largely determined socially; we shouldn't put social forces in place of empirical evidence
[(3) it may be worth mentioning that many Christian theologians at least do not take their faith to imply dualism]

2. argument from introspection

response:
observation often does not reveal the true natures of things; why should mental states be any different?

3. argument from irreducibility of:

(1) language, mathematics
response:
programs to do mathematical work exist; language is being worked on with some success
(2) sensory qualities; meaningful content
C. addresses these later in the book, but notes now that dualism is in no better shape in terms of explaining these
(3) parapsychological phenomena
response:
1 - there is no trustworthy evidence that there are such phenomena
2 - anyway the materialist has at least as much material out of which to construct an explanation as the dualist

Arguments against Dualism

2. explanatory impotence of dualism:  we know a lot about matter and its relation to consciousness; we know nothing about mind-stuff

3. argument from the neural dependence of all known mental phenomena

4. argument from evolutionary history