There is a lot of interesting material at the Consciousness Online conference currently underway. One paper I enjoyed reading was Barbara Montero’s entry on the Russellian theory of mind: “Russellian Physicalism”. In addition to Montero’s paper and powerpoint slides, there are links to responses by Emmett Holman and Daniel Stoljar, who have both also written on this topic in the past (see my old posts here and here).
Montero reminds us that the Russellian approach is a non-dualistic strategy for dissolving the conceivability argument against physicalism/materialism (most famously depicted as the “zombie” argument). David Chalmers' most recent paper updating the conceivability argument had as its conclusion: “materialism is false or Russellian monism is true.”
Russellian monism argues (roughly) that our knowledge of the physical world is only of its extrinsic or dispositional (causal) aspects. Physical entities also have intrinsic or categorical aspects. These hidden aspects are those responsible for consciousness. When we try to conceive of zombies, we fail because we are not conceiving of all relevant aspects of the physical world.
Montero’s paper focuses on the fact that while Russellian monism can be interpreted as a form of panpsychism (the intrinsic aspects are in some fashion mental or experiential in nature), it can also be cast as a variety of physicalism (where the intrinsic aspects are not to be seen as themselves mental).
I'll note parenthetically that both versions face further challenges. In the case of the physicalist version, it can be argued that the explanatory gap between the mental and the physical still isn’t bridged (even though the formal conceivability argument is defeated). In the panpsychist version, we arguably address the gap, but we are left with the “combination” problem: how do micro-phenomenal entities or properties combine to form macroscopic minds like ours?
The responses by Stoljar and Holman and further discussion in the comments mostly revolve around thorny issues of terminology. What do we mean by “physical”, “mental” etc. as it relates to these hidden intrinsic aspects of nature? I tend to like the approach Stoljar took in his book (finally out in paperback), where he threw out these terms and used experiential and non-experiential. Holman proposes using “subjective unity” as the key feature to distinguish things.
I enjoyed the discussion (which continues in the comments), and I hope that philosophers of mind continue to focus on this topic.
Postscript: I have a general quibble, which is that I think this all becomes clearer if you go back and read Bertrand Russell himself (Montero, taking Chalmers as her starting point, includes just one short quote from Russell). Russell’s approach, beginning in his Analysis of Matter, is distinctive for his careful critique of physical theorizing and for his use of a causal event ontology. Russell reminds us that physical theory consists of describing a causal structure connecting the experiential events which occur when we conduct empirical research. The physicists create mathematical models to allow them to generalize and extrapolate to describe events beyond our direct experience. He then argues that it is a philosophical mistake to ascribe reality to the mathematical models themselves (what Whitehead called the “fallacy of misplaced concreteness”). The causally connected events are the reality. We have no good reason to think the “physical” events which we infer have a different character from the events we experience directly. At a minimum we can be confident that an event is ontologically more than just a point in a mathematical model. Whether we think all events are experiential (leading to panpsychism) or not is something for further debate. Russell himself took the conservative option here, and was reluctant to posit panpsychism, while his former collaborator Whitehead went ahead and took the panpsychist step in formulating his process metaphysics (see also my post on Carey Carlson’s book on Russell and Whitehead).