Abstract
Russellian physicalism is a promising answer to the mind–body problem which attempts to satisfy the motivating epistemic and metaphysical concerns of non-physicalists with regards to consciousness, while also maintaining a physicalist commitment to the non-existence of fundamental mentality. Chan (Philosophical Studies, 178:2043–62, 2021) has recently described a challenge to Russellian physicalism he deems the ‘difference-maker problem’, which is a Russellian-physicalism-specific version of the more well-known ‘combination problem’ for Russellian monism generally. The problem is to determine how a relatively small set of fundamental categorical property types can ground the large variety of phenomenal properties that exist. To answer this problem, a Russellian physicalist can say that there is strong emergence from fundamental categorical properties to phenomenal properties, or she can say that there is only weak emergence from fundamental categorical properties to phenomenal properties. Chan argues that neither of these routes are viable for Russellian physicalism. This paper constitutes a response to Chan, arguing that Russellian physicalists can embrace either weak or strong emergence to explain phenomenal variety.
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Notes
These are the defining features of Russellian physicalism as I understand the view. However, Alter and Pereboom (forthcoming) have defended the view that Russellian physicalism is in principle consistent with the existence of scientifically scrutable categorical properties, and Alter and Coleman (2020) have defended the view that Russellian physicalism is in principle consistent with the existence of mentality-specific grounding roles.
Note that the “powerful qualities” view (Heil 2005; Martin 1997) says that properties have both categorical and non-categorical aspects, and that the categorical does not collapse to the non-categorical, nor vice versa. I should note that Russellian physicalism is typically not articulated with this view in mind. Regardless of that, it is a bit hard for me to see how to make sense of this view, since ‘categorical’ typically just means ‘not dispositional/structural/relational’. Given this, the powerful qualities view seems to require that a single property have both a dispositional nature and a non-dispositional nature. Perhaps this view can be made coherent, and perhaps Russellian physicalism can endorse it, but properly figuring this out is unfortunately outside my present scope.
All extant articulations of Russellian physicalism that I am familiar with posit a distinction between fundamental non-mental properties and derivative non-fundamental mental properties. Hence, Russellian physicalism seems to minimally be committed to an ontology of levels, such that there exists a fundamental level upon which everything else depends (even if the “everything else” cannot be cleanly sorted into a neat layer-cake-like model of reality as in Putnam and Oppenheim 1958). It is an interesting question whether Russellian physicalism can be articulated without this commitment, but unfortunately attempting to answer such a large question would take me too far afield.
As I pointed out in footnote one, there is no consensus on whether Russellian physicalism and panprotopsychism are inconsistent. For instance, Alter and Coleman (2020) argue for the view that Russellian physicalism is consistent with a special grounding role for generation of phenomenal properties from fundamental properties. They say that it is physically acceptable for references to intrinsically non-mental categorical properties to be fixed via their mentality-specific grounding roles. Their position is not uncommon among philosophers working on Russellian physicalism—see also Chalmers (2010) and Pereboom (2011). The distinction between Russellian physicalism and panprotopsychism will become more important—and I will discuss it more—in section three.
Notice that the difference-maker problem does not apply only to Russellian physicalism, since it can be put as the general problem of accounting for phenomenal variety given such-and-such grounds for phenomenal properties as posited by some particular account of consciousness. Depending on the theory, the posited grounds for phenomenal properties can be physical or non-physical. Most extant discussion on this issue goes under the heading of the “palette problem” (as in Chalmers 2016) for panpsychism, which is the problem of determining how a small number of fundamental phenomenal property types can give rise to the rich variety of human phenomenology. Of course, there are important differences between the palette problem as it applies to panpsychism—since panpsychists can start off at the fundamental level with a palette of phenomenal properties which are taken to be sui generis—and the difference-maker problem as it applies to Russellian physicalists—since Russellian physicalists cannot avail themselves of a palette of fundamental phenomenal properties.
Chan also has arguments that “phenomenal bonding” requires strong emergence, and so is a false route for those who hold the organization response to the difference-maker problem, and that explaining human-level phenomenal variety in terms of fundamental phenomenal variety (as under panpsychism) does not plausibly provide the resources to account for human-level phenomenal variety. I agree with these arguments of Chan’s, and have chosen to focus on his arguments against what looks to me to be the strongest version of the organization response available to Russellian physicalists—that phenomenal properties are grounded in fundamental categorical properties which are non-phenomenal, as well as fundamental non-categorical properties.
Thanks to Loc-Chi Chan for a helpful discussion on this.
An anonymous referee has suggested that it is possible to interpret this quote as saying that ‘structures and dynamics [alone] can only ground structures and dynamics’. Of course, a Russellian physicalist must grant that structure and dynamics alone cannot ground non-structure and non-dynamics. If this interpretation—which, I should emphasize, is not how I read the provided quote—is correct, then I see no non-question-begging argument from Chan against weak-emergence-embracing Russellian physicalism. Section two below assumes my interpretation of Chan’s quote—specifically, that the motivation for Russellian physicalism is undercut if structure and dynamics are posited to play a difference-making role for phenomenal properties. Notice that my interpretation is consistent with structure and dynamics being the sole difference-maker for phenomenal properties within the actual world. In this case, phenomenal properties can nonetheless depend on the sorts of categorical properties that exist in our world, so long as a metaphysically possible world with different categorical properties than our own would contain different phenomenal properties.
Note that there is no universal agreement on whether strong emergence of any sort is consistent with physicalism, and I will not provide an argument here to support the view that they are consistent, since it is beyond the scope of this paper to provide and substantiate such an argument (though see Zhong 2020 for such an argument). Nonetheless, I will assume, along with Chan, that strong emergence and physicalism in general are consistent.
Specifically, merely bottom-up conceptions of physicalism are ambiguous: these conceptions of physicalism generally define the physical relative to the posits of our best physics. However, does ‘best physics’ mean current physics or future physics? This question leads to Hempel’s (1949, 1969) famous dilemma for physics-based ways of understanding physicalism, which (in my eyes) is a dilemma that has yet to be sufficiently addressed by anyone holding such a physics-based articulation. Specifically, current physics is false, and future physics is vague to the point of meaninglessness, or trivially true if ‘future physics’ means ‘complete physics’. Chan does not attempt to address this dilemma, which is fine, since it is clearly outside the scope of his paper, but it is unfortunately difficult to see exactly how a no-fundamental-mentality constraint follows from most merely bottom-up conceptions of physicalism. For instance, Montero (1999) and Wilson (2006) have respectively argued that a No Fundamental Mentality constraint is an alternative or addition to physics-based understandings of physicalism. Since ‘future physics’ is extremely vague, it is not clear why fundamental mentality would be ruled out. And it is not even clear that current physics rules out fundamental mentality—for instance, under the interpretation of quantum physics in which consciousness collapses the wave functions (see Chalmers and McQueen forthcoming for an argument that this interpretation is plausible).
To see why this is the case, suppose that panpsychism were true. In this situation, paradigmatically physical objects like tables or planets would be composed of fundamentally mental entities. Stoljar (2001, pg. 257) points this out in footnote ten of his ‘Two Conceptions of the Physical’ paper, conceding that extensional articulations of physicalism appear to be insufficient to secure physicalism against what are standardly taken to be non-physicalist views. Chan is aware of this issue with top-down and bottom-up conceptions (referred to as ‘TDBUCs’ in the following quote), saying it is not clear if a satisfactory solution is available. He (pg. 25) specifically says: “It is of course not my purpose here to defend or develop this project; the burden of solving the problem should be left to the proponents of the TDBUCs. However, I have shown that the idea that quarks with qualia-related potencies can be counted as physical appeals to the loophole of the TDBUCs which leads to the problem of excessive liberty. If the loophole were to be closed, the resulting versions of the TDBUCs should exclude quarks with qualia-related potencies, together with quarks with other random, eccentric additions.” This is fair enough, but does admit there is a gap in Chan’s argument against the consistency of physicalism with strong emergence of phenomenal properties. Regardless, my criticism of Chan’s view does not rely on this gap in his argument.
Penrose has the view that microtubules within neurons employ quantum properties in their operations, and that consciousness depends on these quantum operations. The proposed quantum process which is supposed to be consciousness-relevant is called ‘objective reduction’, which is a way of accounting for the measurement problem in quantum physics and collapse of the wave function.I have no stance here on the plausibility of this hypothesis.
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Many thanks to Torin Alter for his helpful feedback.
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Brown, C.D. Answering the Difference-Maker Problem for Russellian Physicalism. Philosophia 51, 1111–1127 (2023). https://doi.org/10.1007/s11406-023-00616-1
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DOI: https://doi.org/10.1007/s11406-023-00616-1