This post is redated and expanded.
Sometimes, when I hear discussion of dualism vs. materialism, I have to wonder how, exactly, the map is being drawn between those positions. What exactly is going to count as dualism or materialism. Just as materialists wonder if defenders of dualism have read or understood the major figures in materialist philosophy, so I sometimes wonder if defenders of materialism are familiar with the different varieties of dualism that have been defended in recent years.
For example, William Hasker's defense of dualism, found in The Emergent Self, is certainly far from insensitive to the developments in neuroscience, and is attentive to the close correlation between mental states and brain states that have been mapped by neuroscientists. In fact, neuroscience provides the primary basis for Hasker's defense of an "emergent" dualism as opposed to a traditional Cartesian dualism. See especially the discussion on pp. 153-157 and 197-198, and there is even a footnote reference to D. Frank Benson's The Neurology of Thinking (Oxford 1994).
I have yet to see anyone grapple with Hasker's book from a materialist perspective, which is too bad. I guess I've done more to solicit materialist response than he has, but he really does offer an across-the-board case against materialism and a well-developed anti-materialist theory to challenge it, and I really didn't do that.
It isn't clear to me that we know, without further clarification, what is meant by terms like "materialism," "substance dualism," "property dualism," and other terms that have been used so often that we are lulled into thinking that we know exactly what they mean.
I provided a typology of positions in the philosophy of mind in my review of Kevin Corcoran ed. Soul, Body and Survival (Cornell, 2001). (Faith and Philosophy July 2004, 393-399.
Standard or Cartesian dualism is committed to these four claims:
1. The mental is sui generis, existing independently of the physical and not in any way reducible to it.
2. Mental states inhere in a thinking thing or substance, not in a bundle.
3. Mental states do not have a location in space.
4. Souls are created individually by God ex nihilo,; they do not emerge from pre-existing material states.
However, I would consider myself a dualist and have some doubts about both 3 and 4. William Hasker and Brian Leftow would be examples of non-standard dualists whose views are represented in the Corcoran volume. Hasker is an emergent dualist and Leftow is a Thomistic dualist.
Standard materialism requires three theses:
1. Physics is mechanistic and is to be described in purely non-mental terms.
2. Physics is causally closed.
3. All states that are not physical supervene on physical states.
Typically a materialism, for example, should not maintain that there is such a thing as libertarian free will, because libertarianism requires the existence of fundamental purposive explanations. But Peter van Inwagen, for instance, calls himself a materialist in the philosophy of mind but also is a defender of libertarian free will. Lynne Baker calls herself a materialist but her first book on the philosophy of mind was an attack on physicalism. So there are nonstandard forms of materialism, as well as nonstandard forms of dualism, and many "Christian materialists" actually reject one of more of the central theses of standard materialism. Good examples would be Lynne Rudder Baker, who calls herself a materialist but whose first book on the philosophy of mind was an attack on physicalism, and Peter van Inwagen, who believes in libertarian free will, (See his book An Essay on Free Will, from which is inconsistent with strict physicalism.
I keep having to say this over and over again, especially when Babinski keeps pointing out that there must be something wrong with my arguments against physicalism because there are Christian philosophers who believe in a materialist philosophy of mind. First of all, if this were true then you could refute any argument for materialism on the ground that some atheist philosophers, like C. J. Ducasse and J. McTaggart believed in life after death, and that atheist existentialist philosopher Jean-Paul Sartre was a Cartesian dualist, or that my college metaphysics teacher, Ted Guleserian, is both and atheist and a mind-body dualist. Now any of these may have good arguments for what they believe, but merely pointing out that they exist does not provide evidence for anything at all.
In my book there is a detailed definition of physicalism, and a slightly broader defintion for naturalism. My arguments are directed against just those positions. Until I get a clear idea of what a person holds, it will not be clear to me if that person is a materialist or a dualist, or maybe a little of both. I keep pointing out, but apparently some people choose not to pay attention, that I could qualify as a materialist on some definitions. (In fact I once heard a paper by a dualist accusing C. S. Lewis of being a non-reductive materialist!)
The kind of dualism William Hasker defends in his book The Emergent Self is called Emergent Dualism. I would appreciate it if people would kindly refrain from stereotyping my positions.