Christopher Devlin Brown

I will argue for two related theses: (i) it is an interest-relative fact whether some metaphysical view counts as monist, and (ii) ‘monism’ can be given a schematic via negativa characterization which says that Φ monism which excludes some property type P in some world W iff only not-P properties are instantiated in W. Property type P can be fundamental, but this is not necessary. As a consequence, it only makes sense to think of monism relative to one or another property type of interest. Classic examples are fundamental mental, normative or abstract properties, but one can imagine other sorts of monism that might be of philosophical interest (e.g. structural properties). Physics-based physicalism satisfies this schema, stipulating that physicalism is true so long as there are no fundamental properties which are not posited by our best physics (regardless of what “best physics” means). I will also argue that my understanding of monism has no supervenience requirement.

Russellian physicalism hopes to satisfy the motivating intuitions of physicalists and non-physicalists alike by offering an account of the fundamental nature of the physical world and suggesting that phenomenal consciousness is grounded in those fundamental physical properties. Mendelow has argued that Russellian physicalism as articulated by Pereboom turns out to make no progress toward answering anti-physicalist challenges on the grounds that the categorical properties posited by Russellian physicalists offer no explanatory help when it comes to the necessitation of phenomenal properties by lower-level physical properties. I argue that Mendelow’s argument fails on the grounds that (i) the intrinsicality of categorical properties offers an answer to the structure and dynamics argument, (ii) Russellian physicalism offers a satisfactory explanation for our epistemic situation, (iii) the choice of categorical properties that Mendelow employs in his argument—absolutely intrinsic sphericity and absolutely intrinsic solidity—are misleading examples, and (iv) the notions of absolutely intrinsic solidity/sphericity are either incoherent, or these properties are not “qualitatively identical” to comparatively intrinsic solidity/sphericity.

Illusionists and a posteriori physicalists agree entirely on the metaphysical nature of reality — that all concrete entities are composed of fundamental physical entities. Despite this basic agreement on metaphysics, illusionists hold that phenomenal consciousness does not exist, whereas a posteriori physicalists hold that it does. One explanation for this disagreement would be that either the illusionists have too demanding a view about what consciousness requires, or the a posteriori physicalists have too tolerant a view. However, we will argue that this divergence of opinion is merely an upshot of the semantic indeterminacy of the term 'conscious' and its cognates. We shall back up this diagnosis by showing how semantic indeterminacy of the kind in question is a pervasive feature of language. By illustrating this pattern with a range of historical examples, we shall show how the dispute between the illusionists and a posteriori physicalists is one instance of a common kind of terminological imprecision. The disagreement between them is thus not substantial. In effect, the two sides differ only about how to make an indeterminate term precise. The moral is that they should stop looking for arguments designed to settle the dispute in their favour.

This book assesses the existentially relevant consequences of physicalism. It argues that accepting physicalism is the healthiest stance we can take in the face of an account of the self and world which offers no metaphysical assurances. Why should we care about physicalism? On one hand, the view seems to be inconsistent with things that many people find valuable, such as the existence of free will, God, the immortal soul, ultimate purpose, and natural laws like karma. On the other hand, physicalism seems to have positive existential implications, such as supporting the unlimited potential of scientific understanding or the attitude that we need not fear supernatural powers or forces because they don't exist. This book argues that physicalism has several consequences that are of existential import. It begins by outlining the history of physicalism and explaining two popular ways of understanding it: the via negativa approach and the theory-based approach. The rest of Part 1 explores the existential consequences of these two versions of physicalism. Part 2 draws on Nietzsche to construct an argument about what attitude we ought to adopt toward physicalism. It argues that we ought to avoid nihilism and despair even when confronted with a picture of the universe which offers no metaphysical assurances. Finally, Part 3 is dedicated to how well physicalism deals with the hard problem of consciousness, mental causation, and multiple realization. The Hope and Horror of Physicalism will appeal to anyone interested in a contemporary approach to existential philosophy, as well as scholars and advanced students working in philosophy of mind and metaphysics.

This paper responds to an argument from Botin which claims that Russellian physicalism is committed to the view that either (i) our phenomenal concepts do not reveal anything essential about phenomenal properties (following Goff, Botin calls this the ‘opaque’ account of phenomenal concepts), or that (ii) phenomenal concepts are capable of revealing at least some of the essence of phenomenal properties—making phenomenal concepts ‘translucent’ if some-but-not-all-revealing or ‘transparent’ if all-revealing—but this entails that phenomenal properties are fundamental, which violates physicalism. I argue that Botin is wrong that Russellian physicalists are committed to the view that physical and phenomenal concepts must have similarly qualitative/phenomenal modes of presentation or contents, since Russellian physicalists assume that we do not possess concepts which specifically refer to non-phenomenal categorical properties. If we were to acquire concepts for non-phenomenal categorical properties, they would need to have categorical contents and modes of presentation, but need not have qualitative/phenomenal contents and modes of presentation. Given this, Russellian physicalists can embrace a translucent account of phenomenal concepts, and hold that our phenomenal concepts more-or-less accurately tell us about certain sorts of non-fundamental properties which are both physical and categorical.

Extensional articulations of physicalism define what it means to be physical relative to the properties of a set of entities, such that physicalism is true if the fundamental properties which compose the entities in this set are the same sorts of fundamental properties which compose everything that exists. Here I present a novel problem for these articulations of physicalism: they are consistent with phenomenal idealism, which is the view that only phenomenal properties exist. Under this view, paradigm physical objects such as tables and chairs are constructed out of more basic phenomenal properties. Since this view says that everything—including paradigm physical entities—is ultimately constituted by phenomenal properties, it follows that this view is consistent with extensional definitions of physicalism, since such definitions only require that there be no fundamental difference between paradigm physical entities and everything else. Yet a good definition of physicalism should not be consistent with phenomenal idealism.

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.

Though there is yet no consensus on the right way to understand ‘physicalism’, most philosophers agree that, regardless of whatever else is required, physicalism cannot be true if there exists fundamental mentality. I will follow Jessica Wilson (Philosophical Studies 131:61–99, 2006) in calling this the 'No Fundamental Mentality' (NFM) constraint on physicalism. Unfortunately for those who wish to constrain physicalism in this way, NFM admits of a counterexample: an artificially intelligent quantum computer which employs quantum properties as part of its cognitive operations. If one of these quantum properties serves a proper functional role in the artificial intelligence, then that property counts as a mental under the physicalism-friendly theory of mentality called “realizer functionalism”, which says that a lower-order property is mental if it satisfies an appropriate higher-order functional description. Further, if this quantum property is both fundamental and mental, then NFM must rule that it is not physical. Yet the existence of such an artificially intelligent quantum computer, which possesses mental properties solely in virtue of the functional roles those properties play, is surely consistent with the truth of physicalism. This ought to motivate NFM proponents to reformulate their view.

Many philosophers identify knowledge of subjective experience as our sole epistemic bedrock of absolute certainty. Illusionism is the view that subjective experience does not exist, and that our belief in the existence of subjective experience is due to a persistent cognitive or meta‐cognitive illusion of some sort. I argue that illusionism entails an absurd epistemic consequence: that our current epistemic situation is consistent with the possible truth of absolute nihilism, which is the view that nothing whatsoever exists. Since it is epistemically impossible that absolute nihilism is true, and the only way to prevent this epistemic possibility is by denying illusionism, I hold that illusionism ought to be rejected.

Russellian physicalism is a view on the nature of consciousness which promises to satisfy the demands of both traditional physicalists and non-physicalists. It does so by identifying subjective experience with physically acceptable categorical properties underlying structural and dispositional properties described by science. Though promising, the view faces at least two serious challenges: (i) it has been argued that science deals in both categorical and non-categorical properties, which would undercut the motivation behind Russellian physicalism, and (ii) it has been argued that only nonphysicalist Russellian views—like panpsychism—are useful when it comes to explaining consciousness. I address these criticisms, arguing that there is no viable reason for maintaining that science deals in categorical properties of the sort which a Russellian physicalist is interested in, and that features of fully-physical categorical properties can be described which provide useful explanations for various essential features of subjective experience. These projects are connected: it turns out that when the explanatory relevance of Russellian physicalism is explained in detail, constraints are put the sort of categorical properties that Russellian physicalists can say are left out of science. Specifically, Russellian physicalists are forced to subscribe to the view that science leaves out any categorical properties whatsoever, as opposed to the view that some scientifically scrutable properties are categorical, but not the ones which Russellian physicalists are interested in. I hope that by addressing these criticisms of Russellian physicalism, and drawing logical connections between the responses, further appeal is added to a promising, but so far relatively unexplored, view.

Regardless of whatever else physicalism requires, nearly all philosophers agree that physicalism cannot be true in a world which contains fundamental mentality. I challenge this widely held attitude, and describe a world which is plausibly all-physical, yet which may contain fundamental mentality. This is a world in which priority monism is true—which is the view that the whole of the cosmos is fundamental, with dependence relations directed from the whole to the parts—and which contains only a single mental system, like a brain or computer. Because some properties of the whole are fundamental under priority monism, it follows that that the mental properties of a cosmos-encompassing brain or computer system may be fundamental in a priority monist world. Yet such a world need not contain anything physically unacceptable: the mental properties of the cosmos-encompassing brain or computer can be characterized in a physicalism-friendly functionalist or identity-theoretic way. Thus, as I see it, physicalism need not be false in such a world. This constitutes a challenge to those who hold the view that physicalism is inconsistent with the existence of fundamental mentality.

Jaegwon Kim maintains that his ‘exclusion argument’ forces us to accept reductive physicalism, which identifies mental and other high-level properties of the world with lower-level properties, over nonreductive physicalism, which avoids such identifications. According to Kim, the exclusion argument shows that any nonreductive view leads to either epiphenomenalism or unacceptable overdetermination of physical effects by physical causes. However, a popular nonreductive physicalist approach called ‘compatibilism’ aims to show that physicalism need not collapse high-level properties into lower-level physical. Compatibilism attempts to block the exclusion argument by attending to the tight modal relationship between higher and lower properties required by nonreductive physicalism. Unfortunately, a similarly tight modal relationship will be embraced by any dualists who hold that natural laws are metaphysically necessary. Despite its increasingly widespread popularity among nonreductive physicalists, it thus seems that the compatibilist’s proposed solution cannot be upheld without removing the barriers to dualists of this sort.

Russellian physicalism has the promise of answering all the typical challenges that non-physicalists have issued against standard versions of physicalism, while not giving up physicalism's commitment to the non-existence of fundamental mentality. However, it has been argued that Russellian physicalism must endorse the existence of physically unacceptable protomental properties in order to address these challenges, which would mean giving up on a core physicalist tenet of keeping the fundamental realm untainted by a special relationship to mentality. Against this, I argue that a plausible version of Russellian physicalism can be constructed, which does not posit fundamental properties that are at all protomental in any problematic sense, yet which can explain the existence of subjective experience. This non-protomental Russellian physicalism, which is the only properly-physical version of Russellian physicalism, offers a satisfying solution to the mind-body problem -- including an answer to the conceivability argument -- without sacrificing any of its physicalist credentials.

Physicalism is frequently understood as the thesis that everything depends upon a fundamental physical level. This standard formulation of physicalism has a rarely noted and arguably unacceptable consequence—it makes physicalism come out false in worlds which have no fundamental level, for instance worlds containing things which can infinitely decompose into smaller and smaller parts. If physicalism is false, it should not be for this reason. Thus far, there is only one proposed solution to this problem, and it comes from the so-called via negativa account of physicalism. Via negativa physicalism identifies the physical with the non-mental, such that if everything in the world ultimately depends only on non-mental things, then physicalism is true. To deal with the possibility of worlds without a fundamental level, this account says that physicalism is false in worlds with either a fundamental mental level or an infinite descent of mental levels. Here I argue that there could be a world with an infinite descent of all-mental levels, yet in which physicalism might plausibly be true—thus contradicting the sufficient-for-false condition meant to save physicalism from the threat of infinitely decomposable worlds. This leaves the need for a new dependence-based account of physicalism.