Neutral monism
Neutral monism is an umbrella term for a class of metaphysical theories in the philosophy of mind, concerning the relation of mind to matter. These theories take the fundamental nature of reality to be neither mental nor physical; in other words it is "neutral".
Neutral monism has gained prominence as a potential solution to theoretical issues within the philosophy of mind, specifically the mind–body problem and the hard problem of consciousness. The mind–body problem is the problem of explaining how mind relates to matter. The hard problem is a related philosophical problem targeted at physicalist theories of mind specifically: the problem arises because it is not obvious how a purely physical universe could give rise to conscious experience. This is because physical explanations are mechanistic: that is, they explain phenomena by appealing to underlying functions and structures. And, though explanations of this sort seem to work well for a wide variety of phenomena, conscious experience seems uniquely resistant to functional explanations. As the philosopher David Chalmers has put it: "even when we have explained the performance of all the cognitive and behavioral functions in the vicinity of experience - perceptual discrimination, categorization, internal access, verbal report - there may still remain a further unanswered question: Why is the performance of these functions accompanied by experience?".
With this, there has been growing demand for alternative ontologies that may provide explanatory frameworks more suitable for explaining the existence of consciousness. It has been accepted by several prominent English-speaking philosophers, such as William James and Bertrand Russell.
Relations to other theories
Since neutral monism provides a potential solution to theoretical problems in the philosophy of mind, it helps to situate neutral monism against its competitors. These competing frameworks can be identified by the relationship they draw between mind and matter, and which of the two they take to be more fundamental.Note that their 'fundamental' is here being used as a technical term. An entity is fundamental if and only if it is irreducible to any other entities. For example, a birthday cake is not fundamental because it can be reduced to its ingredients; a lego-house is not fundamental because it can be reduced to its constituent lego pieces; and a corporation is not fundamental because it can be reduced to its various buildings, employees, and so forth. In contrast, the fundamental interactions of physics are fundamental because they cannot be reduced to any lower-level physical interactions.
Similarly, what is at stake within the philosophy of mind is whether reality has mental properties as fundamental properties. Physicalists would deny this, and insist that consciousness and all mental properties are derivable from some lower-level physical properties. Idealists, in contrast, believe reality is fundamentally mental, and that physical things are nothing more than mind-dependant perceptions. Dualists play both side of the aisle as they believe that reality consists of both fundamentally mental and fundamentally physical elements, each irreducible to the other. Then there are panpsychists, who believe that everything is both mental and physical. Neutral monists break this mold by claiming that the fundamental elements of reality are neither physical nor mental.
Dualism
Neutral monism is similar to dualism in that both take reality to have both mental and physical properties irreducible to one another. Unlike dualism however, neutral monism does not take these properties to be fundamental or separate from one another from any meaningful sense. Dualism is the view that reality is, broadly speaking, made up of two distinct substances or properties: physical substances/properties and mental substances/properties. Neutral monism, in contrast, takes both mind and matter to supervene on a neutral third substance, which is neither mental nor physical. According to Baruch Spinoza, the mind and the body are dual aspects of Nature or God, which he identified as the only real substance.While schematic differences and neutral monism are quite stark, contemporary conceptions of the theories overlap in certain key areas. For instance, Chalmers maintains that the difference between neutral monism and his preferred property dualism can, at times, be mostly semantic.
Panpsychism
Panpsychism is a class of theories that believe that all physical things are conscious. John Searle distinguished it from neutral monism as well as property dualism, which he identified as a form of dualism. However, some neutral monist theories are panpsychist and some panpsychist theories are neutral monist. However, the two do not always overlap. For instance, Russellian monism is not panpsychism in response to the combination problem. Conversely, some versions of property dualism are panpsychist, but not neutral monistic.History
Antecedents
Early examples of neutral monism are found in Indian philosophy. Baruch Spinoza and David Hume provided accounts of reality that may also be interpreted as neutral monism. Spinoza's metaphysics in Ethics argues for a monistic worldview, as well as a neutral one where body and mind are the same. H. H. Price argues that Hume's empiricism introduces a "neutral monist theory of sensation" as both "matter and mind are constructed out of sense-data".In the late 19th century, physicist Ernst Mach theorized that physical entities are nothing apart from their perceived mental properties. Mach ultimately surmises that "both object and ego are provisional fictions of the same kind".
Early 20th century
propounded the notion of radical empiricism to advance neutral monism in his essay "Does Consciousness Exist?" in 1904. William James was one of the earliest philosophers to fully articulate a complete neutral monist view of the world. He did so largely in reaction to neo-Kantianism, which was prevalent at the time.A convert of James, Bertrand Russell advocated for neutral monism, coining the term itself. Russell expressed interest in neutral monism early on his career, and officially endorsed the view from 1919 onward, at least until 1927, when The Analysis of Matter appeared. The ontology of neutral monism conformed to the "supreme maxim in scientific philosophising", as Russell put it in "Logical Atomism" in 1924. Russell's conception of neutral monism went through a number of versions through his career. Russell's own brand of neutral monism, at whichever stage, can be referred to as Russell's neutral monism, but Russellian monism tends to refer to Russell's adherence to the causal theory of perception on the one hand, and the data of consciousness on the other, the latter reduced to neurological events. This view is actually materialist, which neutral monism is not. The version of 1919-1927 is however compatible with logical atomism, Russel's earlier ontology. His position was contentious among his contemporaries; G.E Moore maintained that Russell's philosophy was flawed due to a misinterpretation of facts.
Neutral monism about the mind–body relationship is described by historian C. D. Broad in The Mind and Its Place in Nature. Broad's list of possible views about the mind–body problem, which became known simply as "Broad's famous list of 1925" states the basis of what this theory had been and was to become. Whately Carington in his book Matter, Mind, and Meaning advocated a form of neutral monism. He held that mind and matter both consist of the same kind of components known as "cognita" or sense data. Russian psychologist Boris Sidis also appears to have adhered to some form of neutral monism.
Present
has been known to express sympathy toward neutral monism. In The Conscious Mind he concludes that facts about consciousness are "further facts about our world" and that there ought to be more to reality than just the physical. He then goes on to engage with a Platonic rendition of neutral monism that holds information as fundamental. Though Chalmers believes neutral monism and panpsychism ought to be taken seriously, he considers the combination problem to be point of concern. He considers Russell's solution of "protophenominal properties" to be ad hoc, and thinks such speculation undercuts the parsimony that made neutral monism initially appealing.According to Stephen Stich and Ted Warfield, neutral monism has not been a popular view in philosophy as it is difficult to develop or understand the nature of the neutral elements. Nevertheless, a Machian version of the view has been defended by Jonathan Westphal in The Mind–Body Problem, 2016.
Arguments in favour
Russell was attracted to neutral monism due to its parsimony. In his view, neutral monism offered an "immense simplification" for metaphysics. The upshot of this is that neutral monism provides a solution to the hard problem of consciousness. Annaka Harris formulated the hard problem as "how experience arises out of non-sentient matter"; the neutral monist solves the problem by arguing that if matter is neutral and contains some level of sentience, then one has perceptual contact with the world without needing to explain how experience mysteriously arises from physical matter.An account for how this works relies on creating a distinction between extrinsic properties and intrinsic properties. Extrinsic properties are properties that exist by virtue of how they interact the world and are outwardly observable, such as structures and form. Intrinsic properties are properties exist by virtue of the way they are and are not necessarily outwardly observable. Astrophysicist Arthur Eddington notes that physics can only provide metrical indicators but tells us nothing about the intrinsic nature of things. In other words, most of the positive claims in science are related to the extrinsic properties of reality; that is, with their relationships. However, just because the intrinsic properties of matter are unknown does not mean they do not exist, and in fact may be required. As Chalmers puts it, a world of "pure causal flux" may be logically impossible, for there is "nothing for causation to relate."
Extrapolating from this, philosopher Philip Goff argues in Galileo's Error that consciousness may be the only feature of the universe that we are certain of. It cannot be seen through extrinsic signatures, but we know from first-hand experience that it exists. So if consciousness is the only intrinsic property of matter there is evidence for, and matter must necessarily have intrinsic properties, then one can inductively infer that all matter has intrinsic conscious properties.