TY - JOUR
AU - Wishon,, Donovan
AB - Abstract Neutral monism is the view that both ‘mind’ and ‘matter’ are grounded in a more fundamental form of reality that is intrinsically neither mental nor material. It has often been treated as an odd fringe theory deserving of at most a footnote in the broader philosophical debates. Yet such attitudes do a grave disservice to its sophistications and significance for late nineteenth and early twentieth-century philosophy of mind and psychology. This paper sheds light on this neglected view by situating it within broader historical monist debates about the mind and bringing attention to one of its central internal disputes regarding ‘mental chemistry’. By taking a closer look at how Ernst Mach, William James, and Bertrand Russell address the question of whether and how our mental episodes are composed of more basic elements, it highlights deep differences among their conceptions of the fundamental ‘neutral stuff’ and its relations to ‘mind’ and ‘matter’. 1. Neutral Monism and ‘Mental Chemistry’ Neutral monism is the view that both ‘mind’ and ‘matter’ are grounded in a more fundamental form of reality that is intrinsically neither mental nor material. Its most prominent nineteenth and early twentieth-century proponents included Ernst Mach, William James, and Bertrand Russell.1 While only Russell called his theory ‘neutral monism’ (with Mach preferring the name ‘theory of elements’ and James ‘radical empiricism’) it serves well enough as a unifying label to situate all three within broader monist debates about mind and matter. Mach, James, and Russell found neutral monism attractive for a variety of reasons. Among other things, they saw it as offering a simple, unified conception of reality incorporating both ‘mind’ and ‘matter’ without problematically accounting for either one wholly in terms of the other. They also agreed that it better captures our epistemic situation with respect to ‘mind’ and ‘matter’ than its alternatives while also providing a promising framework for bringing together the natural sciences and scientific psychology. Yet substantive disagreements among Mach, James, and Russell gave very different shape to their respective versions of neutral monism.2 This paper considers how the diverging responses of Mach, James, and Russell to ongoing debates in scientific psychology and philosophy regarding ‘mental chemistry’—whether and how our mental episodes are composed of more basic elements—reveal deep differences in their conceptions of the fundamental ‘neutral stuff’ and its relations to ‘mind’ and ‘matter’. I argue (1) that Mach and Russell agree that ‘mental’ phenomena are composed of more basic neutral elements whereas James largely does not, and (2) Mach and James hold that the ‘neutral stuff’ likely consists entirely of the sorts of qualities and relations we directly encounter in experience, whereas Russell thinks it likely that ‘mind’ and ‘matter’ are composed of elements whose intrinsic natures are inscrutable to us. 2. Transcendental, Absolute, and Personal Idealism Mach, James, and Russell adopted neutral monism in no small part due to their dissatisfaction with popular idealist, materialist, and panpsychist theories of mind, world, and knowledge. Hence, a rough sketch of this broader philosophical context (presented roughly as Mach, James, and Russell understood it) can be useful for understanding certain aspects of their neutral monist theories. Needless to say, a short survey such as this makes no pretension at being exhaustive or doing justice to the many interpretive and philosophical debates it touches upon. Various forms of idealism dominated much of the German and Anglophone philosophical landscape during this period. Broadly speaking, there were three main forms: transcendental idealism, absolute idealism, and personal idealism. The uniting feature of these positions is the Kantian thesis that all human knowledge is mediated through conceptual structures and activities which modify and distort our experience of reality, thereby obscuring its true nature. Transcendental idealists such as Karl Leonhard Reinhold, Johann Gottlieb Fichte, Friedrich Heinrich Jacobi, and Jakob Friedrich Fries typically shared Kant’s concern with identifying the scope and limits of human knowledge and placing scientific knowledge, morality, and/or our religious life on surer footing by grounding them in rational features of our minds. Generally speaking, they viewed themselves as “completing” Kant’s system and/or seeking a more unifying basis for it, such as in the relational structure of consciousness, autonomous rational agency, intuitive faith, logical principles, and so on. In any case, they typically agreed with Kant that reality (as it is independent of human conceptual structures and activities) is a system of incomprehensible things-in-themselves. Proponents of absolute and personal idealism often had great sympathy for Kant’s transcendental idealism, but hoped to reveal deeper unity and interconnection between our mind and the world, appearance and reality, and the various experiential, cognitive, and agential aspects of our mental lives. Absolute idealists such as Georg Wilhelm Friedrich Hegel, Friedrich Wilhelm Joseph Schelling, Thomas Hill Green, Francis Herbert Bradley, and Josiah Royce maintained that reality is ultimately a single, indivisible, spiritual whole. In contrast, personal idealists such as Hermann Lotze, Andrew Seth Pringle-Pattison, John McTaggart, James Ward, and George Frederick Stout held that reality consists of an interconnected community or system of immaterial beings. Many nineteenth-century idealists were well versed in science and made use of it (properly interpreted) in their philosophy. Nonetheless, many held that the universe as we ordinarily experience it is mere appearance (including space, time, and matter) and that no truth about reality, as it is in itself, can be strictly known without apprehending it as a whole. Hence, most idealists gave pride of place to a priori reasoning and reflections on the enabling conditions for human knowledge (including science, mathematics, and geometry) when attempting to discern the ultimate constitution of the world.3 3. Scientific Materialism and Biological Naturalism By the middle of the century, critics of idealism endeavored “to forge arms for the overthrow of transcendental speculations” and gave primacy to more scientific modes of inquiry (Büchner 1864, 251). This was most evident with scientific materialists such as Kurt Vogt, Jacob Moleschott, Ludwig Büchner, and Heinrich Czolbe who sought to account for human psychology and social behavior in terms of the biological sciences.4 In turn, most envisioned reducing biological phenomena such as life, metabolism, reproduction, physiological development, and purposive behavior to complex chemical and physical processes. Whereas idealists attempted to account for matter and our knowledge of it in terms of aspects of our mental lives, scientific materialists conversely sought to account for mental phenomena wholly in terms of material aspects of the world as revealed by the natural sciences (including physics, mechanics, astronomy, geology, biology, physiology, and so on). These materialists gained great notoriety among philosophers and the general population for making such provocative claims as “thought is a motion of matter” (Moleschott 1852, 284) and that it “stands in the same relation to the brain, as bile to the liver, or urine to the kidneys” (Vogt 1845, 206). But many held views about the relation of mind to matter which were less crude. Büchner, for instance, insisted that “thought, spirit, soul, are not material, not a substance, but the effect of the conjoined action of many materials endowed with forces or qualities” (1864, 135–36). As such, he continued, “It can be perceived by our senses as little as any other simple force, such as magnetism, electricity, etc.—merely by its manifestations” (1864, 136). Moreover, they were generally fully cognizant of broader ongoing debates regarding the relations between fundamental physical notions such as ‘matter’, ‘force’, and ‘energy’ and did not think mind was simply little bits of matter stuck together and moving around (Small 1994; Rueger 2012). Thus, they are perhaps more aptly described as ‘physicalists’ than traditional ‘materialists’. Many scientific materialists and biological naturalists such as Ernst Haeckel, Herbert Spencer, Thomas Huxley, Henry Maudsley, and John Tyndall found additional resources for explaining mental phenomena in Charles Darwin’s theory of natural selection (Hatfield 2012; Huneman 2012; Reuger 2012). In his 1859 The Origin of Species, Darwin marshaled a sweeping range of evidence to make the case that gradual changes in biological form and function can result from slight variations among progeny in environments that are harsh, changing, and/or scarce in resources (or reproductive opportunities) over long periods of time. At first, he was wisely reticent about applying his theory to humans. But in later works, Darwin argued expressly that the complexity, diversity, and specificity of human sensory, cognitive, conative, and affective psychological traits (along with linguistic capacities and moral sentiments) are products of natural and reproductive selection tracing back to those of simpler ancestors (1871; 1872). Many naturalistic philosophers also looked for support from the sense-physiological theories of Johannes Müller, Ernst Weber, Hermann von Helmholtz, and Wilhelm Wundt, among others (Hatfield 2002, 2012; Patton 2018; Reed 1994). Müller’s theory of ‘specific nerve energies’ was particularly influential and was later described by Mach as “one of the greatest acquisitions” made by scientific psychology (1910, 193). Müller argued that the activations of specific nerve fibers leading from our sense organs to our brains results in specific ranges of corresponding sensory qualities regardless of the triggering stimulus (1884). As such, the occurrence of specific ranges of sensory qualities indicates that specific nerve fibers (or brain areas to which they are connected) have been suitably activated. So given fairly regular causal connections between specific nerve activations and specific features or changes in the environment, our sensations can thereby function as ‘signals’ for those distal affairs. This offers a way to sidestep vexing issues of how processes in our brains and sense organs can result in transparent presentations or representational ‘copies’ of features of our environments (Patton 2018). For our sensory systems earn their keep simply by picking up useful indirect information about our environment that we can exploit in our practical engagements and activities.5 Yet critics of materialism and naturalism such as Friedrich Albert Lange (1866) and James Ward (1899) saw such causal theories of perception as double-edged swords.6 After all, they argued, if physiology teaches us that our sense organs do not show us how the world really is, then our very conceptions of matter might “have nothing to do with what is really there in the world” (Hussain and Patton 2016; Reed 1994). In this way, these theories of perception meant to pave the way for scientific materialism threaten to undermine our very basis for belief in matter. 4. Panpsychism and Dual-Aspect Theories Many naturalist philosophers and scientists during this period viewed both idealism and materialism as deeply flawed. While they disavowed idealist claims that matter, space, time, and so on, are mere appearances constituted by our cognitive and sensory faculties, they also took materialism to face its own insurmountable problems. Among other things, critics charged that such views run afoul of epiphenomenalism, determinism, nihilism, and/or atheism. Yet the most serious challenges concerned the seemingly inexplicable emergence of life and mind from inanimate and insentient matter. Darwin himself expressed deep uncertainty on such matters: “In what manner the mental powers were first developed in lower organisms, is as hopeless an inquiry as how life first originated. These are problems of the distant future, if they are ever to be solved by man” (1871, 35). Given such concerns, a number of former materialists such as Moleschott, Czolbe, and David Friedrich Strauss, turned instead to Spinozistic dual-aspect theories according to which mind and matter are two irreducible aspects of a common substance, substratum, or reality (Reuger 2012). Often, such theorists hoped to evade thorny issues of mental causation by assuming, at least for methodological purposes, some form of psychophysical parallelism. Others, however, sought a deeper integration of mind and matter and turned instead to panpsychism. In his 1819 Die Welt als Wille und Vorstellung, Arthur Schopenhauer blazed the path for this movement by arguing that: (1) the natural sciences provide abstract mechanical descriptions of the world only as it is extrinsically presented or represented to us perceptually, (2) experience reveals the inner nature of our own outwardly perceived bodies to be a force of striving or will, and (3) considerations such as simplicity, analogy, and continuity suggest that the inner nature of all concrete reality is similarly a (more primitive) form of striving or will (1891).7 Nevertheless, he insisted that inorganic phenomena display “absolutely no trace of a consciousness of an external world” (Skrbina 2007, 120). In contrast, the German philosopher, physicist, and experimental psychologist Gustav Fechner argued that the inner nature of physical phenomena is a form of sentience, feeling, or consciousness rather than will. He envisioned the natural world as containing a vast hierarchy of minded or ensouled entities—with humans and animals occupying a middle ground between the “lower” forms of plants and cells and the “higher” forms of species, planets, stars, and the cosmos as wholes (Skrbina 2007, 2020). In fact, Fechner cofounded ‘psychophysics’ (with Ernst Weber) to study the quantitative relations between sensations and stimuli in hopes of better understanding the relations between the ‘inner’ and ‘outer’ aspects of physical phenomena (Heidelberger 2004; Banks 2003; Hatfield 2012). Other panpsychists, such as William Kingdon Clifford and Sir Arthur Eddington, argued that everything in physical reality is ultimately constituted by ‘mind-stuff’ (Clifford 1878; Eddington 1928). The label ‘mind-stuff’ was not meant to imply, however, that the basic stuff of the world comes in little bits or exhibits full-blown mentality. On the contrary, such theorists insisted that ‘mind-stuff’ lacks the defining features of mental phenomena, such as intentionality, purposiveness, and subjectivity (Strawson 2020). Instead, they conceived of it as loci of nascent feeling or sentience which, when organized into the right kinds of complex systems, results in mental phenomena exhibiting intentionality, purposiveness, and subjectivity. Thus, ‘mind-stuff’ is perhaps better understood as a form of ‘proto-mentality’.8 Mach, James, and Russell each engaged deeply with panpsychism prior to adopting neutral monism and expressed some measure of sympathy for it long after doing so. But for various reasons, they found neutral monism to be more theoretically attractive.9 It should be noted, however, that there are ongoing debates about the exact relationship between various forms of neutral monism and panpsychism. This is especially true of James’s later writings on radical empiricism which, if nothing else, strike a strong panpsychist chord.10 Yet neutral monism arguably departs from panpsychism in a number of crucial respects, especially in the cases of Mach and Russell. 5. Positivism and Phenomenalism Neutral monism first emerged as a serious philosophical movement through Ernst Mach’s scientific and philosophical writings on his ‘theory of elements’. Some aspects of Mach’s theory appeared as early as his 1872 History and Root of the Principle of the Conservation of Energy (Banks 2003). But it reached its mature form in his 1883 The Science of Mechanics, 1886 The Analysis of Sensations, and 1905 Knowledge and Error (Banks 2003). Mach’s early philosophical influences included Kant, Fechner, and Lotze, and he reported gravitating towards idealism, panpsychism, and a psychophysical monadism during the eighteen-sixties (Mach 1891). He was also greatly influenced by scientific theorists such Darwin, Müller, Helmholtz, Wundt, and especially the German philosopher-psychologist Johannes Herbart (Banks 2003, 2018). His general philosophical sensibilities, however, most closely resembled those of David Hume and nineteenth-century positivists such as Auguste Comte and John Stuart Mill. These early positivists rejected a priori metaphysics and conceived of philosophy as a piecemeal empirical investigation of reality continuous with the sciences. Their core thesis was that all scientific and philosophical claims must be based on “positive” evidence that is verified (or at least verifiable) by observation, experimentation, and scientific reasoning.11 Thus, they generally resisted scientific theories appealing to entities, forces, or principles that are unobservable in principle, such as ether, entelechies, vital forces, imperceptible electrical, magnetic, and caloric fluids, and so on (Comte 1853, 243; Jones 1975; Brown 1994). They also typically regarded causal claims as descriptive generalizations of orderly patterns of contiguity and succession among observable phenomena (Comte 1853, 136–37; Mill 1843a, 208). Such positivism led Mill to adopt a highly unorthodox theory of matter (or at least our knowledge thereof). He argued that from a strict empirical standpoint we have no legitimate conception of material bodies except as “permanent possibilities of sensation” for suitably-situated observers (1865, 193–203). On this basis, Mill adopted his notorious ‘phenomenalism’ according to which material objects are, as far as we know, simply complex systems of actual and/or possible sensory experiences of observable qualities and relations (such as arrangements of colors, light, textures, sounds, and so on). Mill’s positivism similarly led him to conclude that minds, as far as we know them, are simply “that which feels” (whatever its underlying nature might be) and that psychology’s proper aim is to describe regularities among “the various feelings or states of consciousness of sentient beings” as well as their physical and physiological conditions (1843b, 219). He was thus pushed towards the view that minds are simply series of experiential episodes (including sensations, feelings, thoughts, desires, volitions, and so on) bearing certain relations to each other, our bodies, and our environments. Yet he also held that many of our mental episodes emerge from complex associative relations among simpler sensations and feelings, and he saw no intelligible way of accounting for their apperceptive unity without the synthesizing activities of an unobserved substantial mind or ego (Reed 1994; Skorupski 1994; Seager 2017). 6. Mach’s Theory of Elements At first glance, Mach’s treatment of matter bears a striking resemblance to that of Mill. He too opposed appeals to entities or forces that are unobservable in principle and called for the natural sciences to be limited to describing the systematic relationships between various observable phenomena.12 In fact, he notoriously resisted the atomic theory on the grounds that “atoms cannot be perceived by the senses” (1883, 393).13 Most importantly, Mach agreed with Mill that (as far as we have any empirical evidence) material bodies are simply groupings of observable sensory qualities bearing causal-functional and spatiotemporal relations with other such qualities. Turning commonsense on its head, he argued that “bodies do not produce sensations, but complexes of sensations (complexes of elements) make up bodies” (1910, 22). But while Mach is often labeled as a ‘phenomenalist’, his treatment of ‘matter’ departs from Mill’s in several crucial respects.14 For one thing, he endorsed a far more expansive list of observable sensory elements, which included not only colors, light, sounds, and so on, but also pressures, intensities, times, spaces, and motor sensations, among other things (1910, 17–18). Mach was also explicit that such ‘sensations’ (as we ordinarily call them) do not occur only in minds.15 Rather, such sensory qualities are real features of the natural world that can remain manifest (albeit differently arranged) after the humans experiencing them perish (1910, 18–20). Conceivably, these elements (or many of them at any rate) could be present even if the universe lacked minds completely, as the sciences tell us it did for vast stretches of its history. Hence, while he often describes them as ‘sensations’, he generally preferred to use the less one-sided term ‘elements’ to designate them. Mach also rejected Mill’s view that ‘material bodies’ are associative groupings of actual and possible sensations on the basis of spatiotemporal contiguity and succession. Instead, he advanced a physiologically-grounded, evolutionary account of perception and cognition according to which our basic notions of ‘things’ and ‘material bodies’ are useful ‘thought-symbols’ for certain series of sensory qualities (colors, tones, pressures, shapes, and so on) of relative spatiotemporal fixedness (1883, 390).16 And the same goes for our basic notions of ‘cause’ and ‘effect’ which are also “things of thought, having an economical office” (1883, 391). We are tempted to ascribe ultimate reality to such notions largely because our use of them is to a large extent instinctive and involuntary (1910, 3). Mach argued that physical notions such as ‘mass’, ‘force’, ‘energy’, ‘electricity’, ‘light-waves’, ‘molecules’, ‘atoms’, and so on are expedient extensions of our basic cognitive tools that “revive economically arranged experiences” and further our practical and economical purposes (1883, 390; 1910, 187). In reality, such “purely mechanical phenomena do not exist” and the belief that mechanics is “the basis of the remaining branches of physics, and explains all physical phenomena by mechanical ideas, is in our judgment a prejudice” (1883, 395). Thus, scientific materialists make the compounding mistake of supposing that matter, forces, atoms, energy, and so on, are both real and the only real things (398). Yet idealists (and dualists) make the converse error of ascribing ultimate reality to notions such as ‘mind’, ‘self’, ‘ego’, ‘spirit’, and so on. In actuality, the ‘self’ or ‘ego’ are similarly instinctive, useful ways of grouping together sensations and other mental episodes bearing certain causal-functional relations with each other (1910, 3). Mach insisted that: The primary fact is not the I, the ego, but the elements (sensations). The elements constitute the I. I have the sensation green, signifies that the element green occurs in a given complex of other elements (sensations, memories). (1910, 19–20) Because they possess “high practical value, not only for the individual, but for the entire species,” Mach argued, “the composites ‘ego’ and ‘body’ assert instinctively their claims, and operate with all the power of natural elements” (1910, 19). Among other things, notions of ‘self’ and ‘ego’ are works “of the highest significance for the intellect in the functions which it performs for the pain-avoiding, pleasure-seeking will” and for preserving our biological organization (1910, 18–20). Mach’s core neutral monist thesis, of course, is that the sensations composing our ‘mind’ are the very same sensory qualities and relations that, together with others we do not happen to observe, compose the material objects we perceive. These sensory qualities are ‘sensible features’ of material objects when grouped with others in terms of the spatiotemporal and causal-functional relations of physics, chemistry, biology, and so on, and at the same time ‘sensations’ in our mind when grouped with others in terms of the causal-functional relations of psychology, psychophysics, sense-physiology, and so on. Mach thus proclaimed: That traditional gulf between physical and psychological research, accordingly, exists only for the habitual stereotyped method of observation. A color is a physical object so long as we consider its dependence upon its luminous source, upon other colors, upon heat, upon space, and so forth. Regarding, however, its dependence upon the retina, it becomes a psychological object, a sensation. Not the subject, but the direction of our investigation, is different in the two domains. (1910, 14–15) This is not to say that every element is a member of both mental and material groupings. But every member of each grouping is, broadly speaking, of the same general kind.17 What renders particular sensible qualities ‘mental’ and/or ‘material’ are the extrinsic causal-functional relations they bear to other such elements, not their specific intrinsic characters. In this sense, physics and psychology share a common (or at least overlapping) subject matter. Mach’s treatment of sensations constitutes only part of his overall account of mental phenomena.18 For the ‘self’ or ‘ego’ is also constituted by series of feelings and ‘percepts’, including perceptions, ideas, volitions, memories, moods, mental images, and so on. Mach was inclined to regard feelings as a species of sensation since “not only tactile sensations, but all other kinds of sensations, may pass gradually into pleasure and pain” (1910, 18). He also thought it likely that “sensations of pleasure and pain, however faint they may be, really make up the contents of all so-called emotions” (1910, 18). But in the case of representational percepts such as perceptions, ideas, volitions, and memories, Mach expressed much hesitation. While he thought it probable that “perceptions, ideas, volition, and emotion, in short the whole inner and outer world, are composed of a small number of homogeneous elements connected in relations of varying evanescence or permanence,” he was unsure of how exactly this could be (1910, 18). Ultimately, he saw this as a question answerable only by “further physiologico-psychological investigations” (1891, 397–98). 7. Mind-Dust and Mental Chemistry Mach was fully aware, however, of potential objections that his theory of elements cannot account for the unity of our mental lives. While such concerns drove Mill, against his positivist sensibilities, towards positing an unobserved substantial self or ego, Mach had a very different response: he simply rejected the premise that the ‘self’ or ‘ego’ is a “definite, unalterable, sharply-bounded … indiscerptible unity” (1910, 20). On the contrary, “the ego is as little absolutely permanent as are bodies” and its appearance of being so “consists chiefly in the fact of its continuity and in the slowness of its changes” (1910, 2–3). Mach argued that such psychological continuity, rather than absolute unity, is what is of chief importance. And this is valuable “only a means of predisposing and of conserving what is contained in the ego,” for “this content and not the ego is the principal thing” (1910, 20). In fact, while our mental lives normally have “enough durable features” to secure their “relative permanency,” even this might be absent in certain pathological cases (1910, 3). Moreover, Mach suspected that the “the fact that the different organs of sensation and memory are physically connected with, and can be readily excited by, one another, is probably the foundation of the ‘psychical unity’” many presume to be ultimate (1910, 20–21). Yet advances in scientific psychology, sense-physiology, psychophysics, and the natural sciences show that “the ego is unsavable” (1910, 20). There are unresolved questions, however, when it comes to Mach’s views about the unity of individual mental episodes. As noted previously, he thought it likely that representational percepts and emotions are in some way resolvable into causally-organized systems of sensations and feelings. But it is unclear whether he took sensations and feelings themselves to be resolvable into more basic elements. Without question, he was fiercely opposed to the idea that they are composed of inscrutable things-in-themselves. Yet there is some evidence that he was open to the possibility of our discovering that such episodes are composed of observable elements which have so far eluded our discrimination: “These elements—elements in the sense that no further resolution has as yet been made of them—are the simplest building stones of the physical world that we have yet been able to reach” (1910, 192). There is also the bigger question about whether Mach believed composite mental phenomena are even real.19 At times, he spoke of ‘mental’ episodes as if they are nothing more than conventional economical groupings of elements and their aggregated causal effects (1910, 20).20 But elsewhere, he described the self or ego, emotions, and various percepts as being composites which are constituted by certain causal-functional arrangements of elements.21 Regardless, Mach was clear that once we recognize that the antithesis of real world and perceived world is due entirely to our mode of view, and no actual gulf exists between them, a rich and variously interconnected content of consciousness is in no respect more difficult to understand than a rich and diversified interconnexion of the world (1910, 21). Hence, he concluded, “the so-called unity of consciousness is not an argument in point” (1910, 21). Moreover, it is not unreasonable to ascribe to Mach the belief that mental phenomena are composed of more basic elements given its prevalence among the psychologist-philosophers who influenced him most. For instance, it is well documented that he was greatly influenced by Herbart’s view that the mind is a mathematically describable system of vying qualitied forces which “fuse” together into “coalitions” to overpower and suppress each other and thereby cross the threshold into consciousness (Banks 2003, 2014, 2018; Landerer and Huemer 2018). Other major influences on Mach, including Fechner, Weber, Wundt, and Helmholtz, also took complex mental phenomena to be composed of more basic elements. The view that complex mental phenomena are composed of simpler elements faced fierce criticism, however. One of the most forceful early challenges was leveled by John Stuart Mill. Like his father (James Mill), he defended an associationist psychology on which complex mental phenomena are the result of various kinds of associative relations among simpler mental phenomena. But unlike his father, Mill denied that such ‘mental chemistry’ (as he vividly dubbed it) involves simple sensations, feelings, and ideas “fusing together” to compose more complex ones (Mill 1869). For one thing, he deemed the very idea of a mere series of mental episodes being aware of itself as a series is paradoxical (1865, 194; Skorupski 1994). For another, we do not experience the simple sensations and feelings allegedly fused together in such cases, so mental fusions would raise “the paradox, of feelings which we have no cognisance of—feelings which are not felt” (1869, 42; Reed 1994). Mill concluded that genuine mental chemistry involves a form of radical emergence: “[a] Complex Idea, formed by the blending together of several simpler ones, should, when it really appears simple … be said to result from or be generated by, the simple ideas, not to consist of them” (1843b, 854; Seager 2017).22 Later critics of mental chemistry such as Ward and James took up and extended Mill’s arguments. In fact, James’s monumental two-volume The Principles of Psychology (1890) advanced a sustained campaign against ‘mental chemistry’ under a multitude of guises, challenging such figures as Herbart, Wundt, Helmholtz, and Clifford as well as associationist psychologists such as James Mill, Herbert Spencer, and Alexander Bain.23 His well-known chapter on ‘mind-stuff’ offers especially incisive criticisms of ‘mental chemistry’ on phenomenological, philosophical, scientific, and logical grounds. For starters, he argued that we do not experience our conscious episodes as being particulate and that “esse in our mental life is sentiri” in the sense that it “must be consciously felt as what it is” (1890a, 157, 172) Moreover, he pressed, the experimental evidence supporting ‘mental chemistry’ is equally compatible with our mental episodes simply having complex physiological causes (1890a, 150–57). Nor do physics and chemistry provide a basis for analogy, as atoms and forces do not actually combine into composites, and appear to do so only due to their aggregate effects on other things (1890a, 159–61). In fact, James asserts that the very notion of mental episodes being compounded out of simpler elements (especially unconscious or insentient ones) is both unintelligible and does violence to the continuity of nature (1890a, 146–49). Nor would it help if the simpler elements are themselves sensations, feelings, or ‘mind-stuff’: Take a hundred [feelings], shuffle them and pack them as close together as you can (whatever that may mean); still each remains the same feeling it always was, shut in its own skin, windowless, ignorant of what other feelings are and mean. There would be a hundred-and-first feeling there, if , when a group or series of such feelings were set up, a consciousness belonging to the group as such should emerge … but they would have no substantial identity with it, nor it with them, and one could never deduce the one from the others, or (in any intelligible sense) say that they evolved it. (1890a, 160) Indeed, he argued, the very logic of identifying complex phenomena with the summation of their parts is paradoxical: “a higher state is not a lot of lower states; it is itself” (1890a, 162–63; Klein 2020). James hoped to provide a more philosophically sound basis for scientific psychology. He proposed that our mental episodes are “pulses” within a seamless stream of consciousness generated by complex neurophysiological processes that directly concern and/or make us aware of external objects and features (1890a, 216–23, 224–90; 1890b, 31–43).24 But they are not themselves decomposable into simpler parts. Rather, the complexity and associative relations many incorrectly ascribe to our mental episodes themselves are instead only properly located among their psychological objects and/or physiological causes (1890a, 550–57). 8. James’s Radical Empiricism Shortly after James completed his 1890 volumes, he began developing his theory of ‘radical empiricism’ on which the primal stuff of the universe is neutral ‘pure experience’. Mach’s theory of elements was an important influence on James’s project, and the two scientist-philosophers were in fact longtime friends and correspondents (Banks 2003, 2014; Klein 2020, forthcoming).25 It was also shaped by Avenarius’s neutral monist theory of ‘pure experience’ (the source of James’s term), though it is unclear how far such influence went (Lamberth 1999, 83–87).26 What is clear is that James’s project had both philosophical and scientific motivations (Lamberth 1999; Klein 2015). On the philosophical side, James hoped to build up “a sort of elementary description of the constitution of the world” (as he put it in a 1902 letter to Mach) on the basis of a radical empiricism that avoids both inscrutable things-in-themselves and the starkness of classical empiricism and positivism.27 For “to be radical, an empiricism must neither admit into its constructions any element that is not directly experienced, nor exclude from them any element that is directly experienced” (1904b, 195).28 On the scientific side, James was largely concerned with issues regarding the empirical foundations of experimental psychology. In The Principles of Psychology, he was openly conflicted about appeals to a notion of a substantial self or ego given its ostensibly transempirical character, and he grudgingly accepted its legitimacy largely out of the absence of any promising alternative. In contrast, he had readily treated our awareness and knowledge of the world as transempirical, primitive relations—a stance sharply criticized by the American philosopher and psychologist George Stuart Fullerton (Klein 2015). Yet James too was uneasy about our evidential grounds for thinking that mental acts directly acquaint us with extramental reality: “[experience] does not come to us immediately as a relation between two realities, one mental and one physical” (1892, 398). James soon concluded that experience has no subject-object “inner duplicity” and that “the separation of it into consciousness and content comes, not by way of subtraction, but by way of addition” (1904a, 172).29 In fact, he boldly pronounced, ‘consciousness’ … is the name of a nonentity, and has no right to a place among first principles. Those who still cling to it are clinging to a mere echo, the faint rumor left behind by the disappearing ‘soul’ upon the air of philosophy. (1904a, 169) In saying this, he was not denying the existence of consciousness altogether, but only that “the word stands for an entity” (1904a, 170). He insisted “most emphatically that it does stand for a function” (1904a, 170). Specifically, “‘consciousness’ is supposed necessary to explain the fact that things not only are, but get reported, are known,” and “whoever blots out the notion of consciousness from his list of first principles must still provide in some way for that function’s being carried on” (1904a, 170). What is crucial is that this is a function involving only phenomena which are observable (at least in principle). James similarly rejected other purported mental dualities for not being manifest in pure experience but rather imposed on it by our conceptual and linguistic schemes. These include such distinctions as between ‘thoughts’ and ‘things’, ‘knower’ and ‘known’, and ‘mind’ and ‘matter’. In reality, there is “no aboriginal stuff or quality of being, contrasted with that of which material objects are made, out of which thoughts of them are made” (1904a, 170). Pure experience is (as far as we know) the only “primal stuff or material in the world, a stuff of which everything is composed,” including ‘mind’ and ‘matter’ (1904a, 170). Echoing Mach, James maintained that pure experience consists of exactly the sorts of elements we experience: a rich diversity of sensory qualities such as colors, sounds, intensity, flatness, heaviness, spaces, times, and so on (1904a, 179). But he was emphatic that it also includes various “conjunctive” and “disjunctive” relations, including (1) relations of similarity and difference, (2) spatial and temporal relations (such as simultaneity, time-interval, space-adjacency, and distance), (3) relations of activity (such as change, tendency, resistance, and causation), (4) mental relations (such as memories, purposes, and strivings), and (5) relations of continuity and discontinuity (1904b, 197–99). More generally, “reality is made of as many stuffs as there are natures of the things experienced” (1904b, 179). In this sense, James’s radical empiricism is pluralistic about the specific sorts of elements that constitute the world, yet monistic in the sense that they are exclusively sensible qualities and relations. James argued that this conception of reality opens the possibility for experimental psychology to provide a wholly empirical account of our mental lives. For on such a view, consciousness, cognition, memory, attention, volition, and so on, “can easily be explained as a particular sort of relation towards one another into which portions of pure experience may enter” (1904a, 170). Furthermore, “the relation itself is a part of pure experience; one of its ‘terms’ becomes the subject or bearer of the knowledge, the knower, the other becomes the object known” (1904a, 170).30 Thus, there is no need to appeal to unobservable entities such as ‘egos’, nor to unobservable relations such as “diaphanous” mental acts (Moore 1903). James also followed Mach in holding that one and the same part of pure experience can be ‘mental’ and/or ‘material’ depending on the context and the functional relations it bears to other such portions: a given undivided portion of experience, taken in one context of associates, [plays] the part of knower, of a state of mind, of ‘consciousness’; while in a different context the same undivided bit of experience plays the part of the thing known; of an objective ‘content’. In a word, in one group it figures as a thought, in another group as a thing. (1904a, 172) In the case of ‘matter’, the relevant functional relations are the various spatial, temporal, and “energetic” relations studied by physics, chemistry, geology, and other natural sciences. In the case of ‘mind’, they include those studied by experimental psychology: relations of consciousness, cognition, memory, attention, volitions, and so on, which are present in a continuous “train of sensations, emotions, decisions, movements, classifications, expectations, etc.” (1904a, 173–74; Cooper 2002, 4). In this sense, James’s radical empiricism was (arguably) a form of neutral monism very much like Mach’s theory of elements.31 Yet James departed from Mach in at least one fundamental respect: he retained his fierce opposition to ‘mental chemistry’. Specifically, he continued to reject the idea that our mental lives are composites of discrete units combined or fused together by means of some form of ‘causal glue’. Instead, our mental lives consist of variously-related “portions” of pure experience which “pass into” one another so as to constitute a single continuous “stream of consciousness” (1904b, 196–99). He argued that the portions of pure experience of a single self are unified in this way by the unique conjunctive relation of ‘co-conscious transition’, which we experience directly as an unbroken “withness” among our mental episodes (in contrast to the break or discontinuity we experience between our mental episodes and those of others) (1904b, 197). He took this relation of co-conscious transition to be metaphysically primitive, possessing “no other nature, no other whatness than this absence of break and this sense of continuity in … the passing of one experience into another” (1904b, 198).32 And whereas Mach and Russell took the self to be a certain kind of causally-organized system of neutral episodes, James held that “the organization of the Self as a system of memories, purposes, strivings, fulfilments or disappointments, is incidental to this most intimate of all relations, the terms of which seem in many cases to compenetrate and suffuse each other’s being” (1904b, 196). James was not in wholesale opposition to the idea that mental episodes often have ‘parts’ or ‘fuse’ together, however. He simply denied that such cases involve discrete elements coming together to form discretely bounded wholes. In his view, portions of pure experience do not come in literal ‘bits’ but rather in “concrete pulses [that] run into one another continuously and seem to interpenetrate … inwardly they are one with their parts, and outwardly they pass continuously into their next neighbors” (1909, 294–95). Accordingly, “mental contents should be called complex, just as their objects are,” but “not because their parts are separable, as the parts of objects are, not because they have an eternal or quasi-eternal individual existence, like the parts of objects… Still, in them, we can call parts, parts” (1895, 168).33 James held that the received notion of ‘mental chemistry’ results in part from misconceptions about the cognitive role of concepts. They are not simply representations or ‘signs’ introduced to indicate or designate distinct aspects of reality. Rather, concepts are cognitive tools that make discrete “carvings” or “partitions” within the continuous field of pure experience based largely on our practical interests. As such, their cognitive content need not be reflective of the structure of reality itself, but rather is based on the course of experiences they lead to, purposes they serve, and practical effects they result in (1911, 232–43).34 This aspect of James’s radical empiricism is one with which Mach was very much sympathetic, but which Russell found problematic. 9. Russell’s Road to Neutral Monism Russell had a complicated history with neutral monism. A standard telling (with added scholarly detail) might go something like this: Russell first encountered neutral monism while drafting a 1912 review of James’s Essays in Radical Empiricism. Despite finding it enticing, he soon launched a systematic critique of it in his abandoned 1913 Theory of Knowledge manuscript, focusing primarily on the views of Mach, Perry, and especially James (Papers 7).35 Yet his sympathies for neutral monism gradually increased until he finally converted to the view in his 1919 “On Propositions” (Papers 8, 276–306).36 Thereafter, he championed it for roughly a half century (Eames 1967). In actuality, Russell’s engagement with neutral monism began far earlier than has been recognized. Russell first read Mach’s Science of Mechanics in 1895 and referenced him several times in his earliest publication: a review of a two-volume textbook written by the Dutch panpsychist and psychophysicist Gerardus Heymans (1895).37 Three years later, Russell read his teacher James Ward’s Gifford Lectures and helped him prepare it for publication as Naturalism and Agnosticism (1899). In these lectures, Ward discussed both Mach and Avenarius (along with Fechner, Clifford, and Spencer, among others) in the course of championing a pluralistic idealism over materialism, positivism, dual-aspect theories, mind-stuff theories, and even ‘neutral monism’. Indeed, while Russell is widely credited with coining the term, Ward had used it almost two decades earlier.38 Russell returned again to these topics in 1901 when reading the published version of Ward’s work shortly after his own self-proclaimed “revolt” from idealism. During this initial post-idealist period, Russell held that our most basic form of experience consists of a direct, unmediated awareness of aspects of reality as they are independent of human thought. Following James (1890a), he called such direct awareness ‘knowledge by acquaintance’. And following Brentano (1874), he conceived of it as a special (real) epistemic relation between our mind and objects that are typically outside of our minds: “the faculty of being acquainted with things other than itself is the main characteristic of a mind … it is this that constitutes the mind’s power of knowing things” (1912a, 66–67).39 Russell’s early criticisms of neutral monism were largely driven by this relational conception of mental phenomena. Among other things, he charged that it conflicts with our direct experience of the relational character of mental acts, cannot explain the immediate difference between what is and is not experienced, and offers problematic accounts of cognitive phenomena such as selective attention, judgment, and egocentric thought (Pincock 2018). Even so, he expressed great sympathy for the view, saying Occam’s razor “prescribes James’s theory as preferable to dualism if it can possibly be made to account for the facts” (Papers 7, 21). Russell’s changing attitudes towards neutral monism were largely based on three factors (1959, 135). First, he became increasingly dissatisfied with the ‘multiple-relation theory of judgement’ he had championed for roughly a decade and was primed to reimagine cognitive phenomena down to their very foundations (MacBride 2013). Second, Russell came to deny that we have introspective evidence either of an ego or of intrinsically relational mental acts (Wishon 2018). And third, he gained confidence that, with ingenuity, neutral monism could explain the features of our cognitive lives he had previously deemed recalcitrant to nonrelational analyses. 10. Russell’s Analysis of Matter Finding himself in agreement with James, Mach, and the American New Realists, Russell concluded that: The stuff of which the world of our experience is composed is, in my belief, neither mind nor matter, but something more primitive than either. Both mind and matter seem to be composite, and the stuff of which they are compounded lies in a sense between the two, in a sense above them both, like a common ancestor. (1921, 10–11) Like Mach, Russell proposed that ‘minds’ and ‘matter’ are composite systems of more basic elements that are intrinsically neither ‘mental’ nor ‘material’. When organized in terms of the causal relations studied by psychology, these elements become ‘mental’. When organized in terms of certain causal relations studied by the physical sciences, these elements become ‘material’. In some instances, the same elements will be members of both kinds of groupings, in which case they will be both ‘mental’ and ‘material’. Yet the vast majority of these elements are subject only to physical causal relations and so are solely ‘material’.40 Russell was not a ‘materialist’, however. For one thing, these elements are not intrinsically ‘material’, but rather only in virtue of their extrinsic relations to other elements.41 For another, he viewed physics itself as having dispensed with the notion of ‘matter’ in the wake of new discoveries about the relativity of space and time, the structure of the atom, and the strange realm of quantum phenomena (1921, 5–6). Specifically, he argued that physics no longer describes the universe as being composed of ‘little hard lumps’ located at specific points in space, crowding out other such lumps, and enduring through various changes in their features (1927b, 214). Instead, ‘matter’ is simply a convenient way of describing certain complex, causally organized series of transitory (and sometimes overlapping) occurrences unfolding within relativistic spacetime (1927b, 124–27). In fact, “everything in the world is composed of ‘events’… having a small finite duration and a small finite extension in space; or rather, in view of the theory of relativity, [they are occurrences] occupying a small finite amount of space-time” (1927b, 222). Consequently, “matter, in modern science, has lost its solidity and substantiality; it is becoming a mere ghost haunting the scenes of its former splendors” (1927b, 235). Concluding that “James had been right in denying the relational character of sensations,” Russell replaced his well-known ‘sense-data’ theory with new analyses of perception and our knowledge of matter (1959, 134). He argued that sensing is simply the occurrence of ‘percepts’ (certain combinations of sensory qualities and relations) within a psychologically-organized system of events bearing certain causal-connections to distal affairs (1927a, 320). At the same time, these same occurrent sensory qualities also participate in complex physically organized processes stretching across spacetime. In fact, “the sensation that we have when we see a patch of colour simply is that patch of colour, an actual constituent of the physical world, and part of what physics is concerned with” (1921, 142). But whereas Mach and James took the sensory qualities we experience to be parts of ‘material’ objects in our environment, empirical considerations in physics, psychology, and physiology convinced Russell that perception cannot be as straightforward and direct as they had suggested. Instead, perception is a complicated causal process whereby systems of events radiate outward from a source until they reach and modify such things as photographic plates or our nervous systems (1927a, 320). In the latter case, such modifications often produce percepts which serve as the basis on which we make ‘unconscious’ inferences about their source causes based on presumptions of the spatiotemporal and causal continuity between these events, that different effects result from different causes, and that causal chains unfold along distinguishable spatiotemporal paths (190, 398–402; 1948, 506–15).42 In doing so, we acquire nondemonstrative knowledge about the mathematically describable spatiotemporal and “causal skeleton of the world” (1927a, 391). Yet aside from certain of our percepts and other mental events, we are left in the dark about the intrinsic nature of the events and relations the natural sciences abstractly describe: “as regards the world in general, both physical and mental, everything that we know of its intrinsic character is derived from the mental side, and almost everything that we know of its causal laws is derived from the physical side” (1927a, 402). Russell thus urged caution when speculating about the nature of events outside the brain. Their intrinsic characters might closely resemble those of our percepts, but they might also be “totally different in strictly unimaginable ways” (1959, 13). In the end, “physics is not mathematical because we know so much about matter, but because we know so little” (1927b, 125).43 11. Russell’s Analysis of Mind Russell’s initial neutral-monist analyses of mental phenomena echoed Mach’s in treating minds as psychologically-organized systems composed entirely of ‘sensations’ and ‘images’ (1921, 69). This, together with his claims that matter is composed of “constituents analogous to sensations” which more closely resemble ‘mental’ events than traditional ‘matter’, have led some to view Russell’s theory as a form of panpsychism or phenomenalistic idealism on which mind is a fundamental feature of reality (Russell 1921, 108, 306; 1927a, 388; Maxwell 1972; Quinton 1972; Savage and Anderson 1989; Brüntrup 2017). But this is a mistake. For Russell held that all ‘mental’ phenomena are complex episodes composed of more basic ingredients that (we have reason to believe) are not themselves mental: “I think ‘mental’ is a character, like ‘harmonious’ or ‘discordant’ that cannot belong to a single entity in its own right, but only systems of entities” (1927b, 161). In reality, Russell set out precisely to provide a fully naturalistic analysis of ‘mental’ phenomena: “I was anxious [as a dualist] to rescue the physical world from the clutches of idealism … . But if I could rescue the so-called ‘mental’ world from him too! Then the reason for making a gulf between the mental and the physical would disappear” (Papers 8, 255). In particular, Russell aimed to follow Dewey (1916) in “[reducing] everything cognitive to ‘pure natural events’,” and acknowledged that in this regard his neutral monism’s “bias or flavour is materialistic” (Papers 8, 135, 254). Moreover, Russell repeatedly disputed charges that his neutral monism is a covert form of idealism or panpsychism. Writing to the publishing editor of an early review of his 1921 The Analysis of Mind, Russell protested that: Your reviewer believes that I regard matter as a ‘collocation of sensations’ and naturally finds difficulty in understanding what I mean by a ‘purely physical world’. I had tried to guard against this misconception [that our ‘sensations’ are intrinsically ‘experiential’ in character] by the illustration of a photographic plate… . The philosophy which your reviewer imputes to me is a Berkeleian idealism, whereas the philosophy I hold is neither idealism nor materialism, and allows the possibility of a world containing nothing mental. (Papers 9, 32) Elsewhere, he insisted that his claim that ‘minds’ and ‘mental phenomena’ are wholly composed of ‘sensations’ and ‘images’ was not meant to convey that all such components are intrinsically ‘experiential’ in character. Rather, he used these terms primarily to indicate the specific causal roles of the relevant episodes: When I say that the stuff of the mind consists only of sensations and images, I doubt whether what I am saying is more than verbal. Mental phenomena, like all other phenomena, consist of particulars variously related. Sensations and images are merely names for these particulars, sensations being those which have proximate causes outside the brain, and images being all the rest. (Papers 10, 296) Therefore, ‘minds’, ‘sensations’, ‘images’, and similar notions are to be understood as complex systems of natural events which happen to be ordered by the distinctive causal relations investigated by psychology (without precluding them from also being ‘physical’). In fact, Russell denied there being any special character that marks ‘mental’ episodes out from other occurrences and raises “an impassable gulf” between ‘mind’ and ‘matter’ (1921, 9–11). Most notably, he rejected the notion that ‘consciousness’ is a fundamental “character diffused throughout our mental life, distinct from sensations and images, memories, beliefs and desires, but present in all of them” (1921, 288). In his estimation, philosophers and psychologists variously use the term ‘consciousness’ in at least three different senses: as a special kind of (a) intrinsic quality of mental phenomena, (b) awareness of the world, and/or (c) awareness of one’s own mental episodes (1921, 112–13). But in each of these cases, Russell argued, such characteristics apply only to composites of more basic elements. Russell granted that ‘consciousness’, conceived as a form of awareness, is a ‘special’ relation directed at objects or our own mental episodes. But it does not follow that such awareness is unanalyzable or among the basic ‘furniture’ of the world. On the contrary, certain episodes constitute cases of objectual awareness by (1) bearing the right external causal relations to remote spacetime events and (2) occurring as part of an organized system of events exhibiting a marked degree of ‘sensitivity’, ‘mnemic’ responsiveness, and ‘subjectivity’ (1927b, 171). As I have noted elsewhere, Russell held that a system “is ‘sensitive’ to a certain feature of the environment if it behaves differently according to the presence or absence of that feature” in the same sense that “iron is sensitive to anything magnetic” (1921, 260; Wishon 2020). And just as scientific instruments are designed so that certain changes in their components reliably indicate certain features of the environment which are unobservable and/or useful for us to measure, certain changes in our nervous systems (and those of other biological organisms) can reliably signal the presence or absence of certain distal features which are, in many circumstances, useful for us to detect (1921, 131–36, 255–61; 1959, 19, 103). According to Russell, systems exhibit ‘mnemic-responsiveness’ when their responses to stimuli tend to be shaped considerably by earlier episodes in their biographies. Mnemic responses, then, are ones whose “proximate cause consists not merely of a present event , but this together with a past event” (1921, 85). This characteristic can be present in ‘dead matter’ (such as in magnetized steel), but it plays a more “persistent” and “important” role in shaping the behavior of humans, animals, and plants, usually in ways that are “biologically advantageous to the organism” (1921, 78). Russell’s examples of mnemic phenomena include acquired habits, psychological associations, nonsensational elements in perception, and memories, among other things (1921, 79–82, 198–203, 285–86). Mnemic causal relations also unify events in small regions into ‘perspectives’ exhibiting ‘subjectivity’ (“the characteristic of giving the view of the world from a certain place”) based on how they are situated with respect to other spacetime events (1921, 101, 296). Photographic plates, for instance, exhibit ‘subjectivity’ in the relevant sense in that they represent the events to which they are sensitive from the ‘perspective’ or place they are located (1921, 100–102, 130–31). In the case of humans and other organisms, ‘subjectivity’ is similarly a matter of certain of their component events exhibiting a high degree of sensitivity and mnemic-responsiveness to other events “from a place where there is a brain (or, in lower animals, some suitable nervous structure), with sense-organs and nerves forming part of the intervening medium” (1921, 131). Russell argued that the difference between the ‘biographies’ of biological organisms and inorganic systems is also a matter of the presence of complex mnemic relations, rather than mere spatiotemporal continuity, among their constituent parts (1921, 129–30). In fact, certain complex mnemic relations among episodes within a single subjective biography are precisely what (1) transform mere happenings into ‘experiences’, (2) constitute the unity of one ‘experience’, and (3) constitute the continuity of a ‘person’ or a ‘mind’ (1921, 129). Russell thus objected to James’s use of the term ‘pure experience’ to describe “the whole primal stuff of the world” and praised Perry and Holt for having dropped it (1921, 82). He suggested on several occasions that “the use of the phrase ‘pure experience’ [by James] points to a lingering influence of idealism” (1921, 24–25; 1945, 813). By his lights, “‘experience,’ like ‘consciousness,’ must be a product, not a part of the primary stuff of the world. It must be possible, if James is right in his main contentions, that roughly the same stuff, differently arranged, would not give rise to anything that could be called ‘experience’” (1921, 25). Indeed, he argued, “in a purely physical world, things would happen without there being any experience. It is only mnemic phenomena that embody experience” (1921, 82). Russell argued that we might even have empirical grounds for concluding that our experiences are composite. Among other things, certain experimental evidence concerning ‘just noticeable differences’ suggested to him that “all our percepts are composed of imperceptible parts” and have imperceptible structures (1927a, 282, 386). Of course, this leaves open the key question of the nature of the elements composing our percepts. And while postulates of continuity and simplicity in nature suggest that they too are qualities and relations of some kind, we are otherwise left in the dark about them. Indeed, Russell cautioned, “it must not be assumed that part of a mental state must be a mental state” (1927a, 320). Nor should we assume that they are intrinsically ‘mind-like’ or ‘experience-involving’ in any significant sense simply because the only qualities with which we are acquainted are those of our own ‘experiences’ and ‘mental’ episodes. For what lends episodes such status, he argued, are extrinsic facts about their mnemic relations to other occurrences rather than their specific intrinsic characters. Take ‘sensations’ for instance: “sensations” are to be defined as “those particulars which happen to be experienced.” It follows tautologically that I cannot give an instance of a particular which is not a sensation. This, however, is not an important metaphysical truth, any more than the fact that I cannot give an instance of a man I have never heard of. (Papers 9, 32). For the same basic reason, we have no grounds for supposing that there is a special “intrinsic character by which a ‘conscious’ experience could be distinguished from any other” (1921, 113). Finally, as I have noted elsewhere, Russell held that there are three different ways we can achieve ‘self-consciousness’ of our mental episodes (Wishon 2020). Most primitively, we in some sense can ‘feel’ the qualities of our sensory episodes simply by ‘experiencing’ them: by having them occur in the right way within our subjective mental biography (1921, 139–42). We can also ‘notice’ such sensory episodes when they function as ‘prototypes’ for cognitive episodes which are sensitive to them, resemble them in some way, and involve feelings that ‘this is occurring’ or ‘this occurred’ (1921, 288–89). Lastly, we can ‘notice’ our cognitive episodes and other mental images via other such episodes with (roughly) the same ‘prototypes’ or contents by exploiting suitable associative relations between them (1921, 290–91). From all of this, Russell concludes that “consciousness is far too complex and accidental to be taken as the fundamental characteristic of mind” (1921, 292). And the same goes for other kinds of mental episodes as well, including ‘beliefs’, ‘desires’, ‘emotions’, ‘volitions’, and so on (1921, 69, 300). In fact, at various points, Russell voiced having some desire to expunge such notions from experimental psychology altogether: “There are a number of words which I think should disappear from the psychological vocabulary: among these I should include knowledge, memory, perception, and sensation” (Papers 10, 295). This is not because such notions are pure fantasy. Rather, it is because such labels give the false impression that the episodes they designate are simple, indiscerptible, and irreducibly mental. In reality, they are highly-organized systems of pure natural events which collectively exhibit varying combinations of sensitivity, subjectivity, and mnemic-responsiveness. And he thinks we have some (inconclusive) grounds for inferring that they have parts and structure that we do not experience. 12. Conclusion Neutral monism has often been treated as an odd fringe theory deserving of at most a footnote in the broader philosophical debates. Yet such attitudes do a grave disservice to its sophistications and significance for late nineteenth and early-twentieth century philosophy of mind and psychology. So, it is encouraging that there has been growing interest in neutral monism and its potential contributions to our understanding of the place of mind in the universe. This paper contributes to this modest revival by situating such views within broader historical monist debates about the mind and bringing attention to disagreements between Mach, James, and Russell on the issue of ‘mental chemistry’. Among other things, I have argued that (1) Mach and Russell departed from James in holding that ‘mental phenomena’ are composites of more basic neutral elements, and (2) Mach and James departed from Russell in holding that the fundamental ‘neutral stuff’ consists entirely of the sorts of qualities and relations we encounter in experience rather than ones whose intrinsic natures are inscrutable to us.44 Footnotes 1 Other notable neutral monists included John Dewey, Ralph Barton Perry, Edwin Holt, Richard Avernarius, Joseph Petzoldt, Moritz Schlick, F.C.S. Schiller, and Alexander Bogdonov. More controversially, Baruch Spinoza, David Hume, John Stuart Mill, and certain logical positivists are also sometimes classified as neutral monists. Notable critics of neutral monism included James Ward (1899), Boyd Henry Bode (1905a; 1905b), Vladimir Lenin (1909), Carl Stumpf (1910), Arthur Eddington (1928), Arthur Lovejoy (1930), and Charles Hartshorne (1937). For a general introduction to neutral monism, see Stubenberg (2018). 2 Recent scholarship on these internal debates include Bailey (2020); Banks (2003, 2014, 2018); Hatfield (2002, 2004, 2015); Klein (2017, 2020); Landini (2011); Pincock (2019); Stubenberg (2017, 2018); and Wishon (2015, 2020). 3 As one notable exception, Stout turns a common materialist argument on its head and defends idealism as the best explanation of our evidence for systematic psychophysical correlations, the causal efficacy of mental phenomena, and the conservation of energy in the universe (1889, 46–54). 4 Scientific materialism must be distinguished from the historical materialism of figures such as Ludwig Feuerbach, Friedrich Engels, Karl Marx, and Vladimir Lenin. 5 Isaac (2019) makes a strong case that Müller’s theory of perception is, in essence, an early version of epistemic structural realism of the sort Russell would later defend. 6 Incidentally, Russell would later write the introduction to an English translation of Lange’s monumental The History of Materialism and Criticism of Its Present Importance. In a letter to the publishing editor, Russell reported finding Lange “extremely good and I can praise him whole-heartedly, though I think he over-estimates Kant” (Papers 9, 293). Naturally, his introduction frequently alluded to the superiority of neutral monism over materialism. 7 In point of fact, Schopenhauer held that we derive our notion of ‘force’ from our more basic grasp of ‘will’ rather than the other way around (1891, 144–45). 8 Other notable panpsychists during this era included Friedrich Paulsen and Geradus Heymans (both former students of Fechner), Morton Prince, Durant Drake, Charles A. Strong, Charles Sanders Pierce, and Charles Hartshorne, among others (Skrbina 2007, 2020; Goff, Seager, and Allen-Hermanson 2020). Alfred North Whitehead and Henri Bergson are also frequently described as panpsychists. 9 For Mach’s objections to Fechner’s panpsychism and Clifford’s “mind-stuff” theory, see his “Some Questions of Psycho-Physics” (Mach 1891). For more on Russell’s views about panpsychism, see Wishon (2020). 10 In contrast, James is openly critical of dual-aspect theories (1912, 184–85). 11 Note that direct observation is not the same things as naïve or transparent observation. Comte held that observation generally requires a progression of prior theoretical scaffolding (1853, 135) and that Mill held that “a great part of what seems observation is really inference” (1843b, 641). 12 Banks (2014) argues that Mach, inspired by both Fechner and Herbart’s forceful presentations psychology, conceived of his elements as forceful qualitative events that are manifestations of causal powers. But such descriptions seem to suggest that the elements derive from more fundamental, unobservable aspects of reality. As I read Mach, it would be more apt to turn things around say that the notion of ‘causal powers’ is a convenient shorthand for talking about certain patterns of interaction among forceful qualitative events. 13 For more on Mach’s various controversial stances in physics, see Banks (2003) and Banks (2014), especially chapter one. 14 Interestingly, Russell (1895, 1918, Papers 7) and James (Klein 2020) are both among those who dubbed Mach a ‘phenomenalist’. This is likely due to the fact that the term ‘phenomenalism’ is sometimes applied to views on which the world (as far as we know) consists entirely sensory qualities in space and time. 15 Mill was frustratingly ambiguous on this point. He clearly insisted that the possibilities for certain groups of sensations remain present in the absence of any observers whatsoever, but it is less clear whether the sensory qualities themselves do so (1865, 198–203). Mill’s caginess on this issue has led him to be interpreted variously as a neutral monist (Wilson 2007) and as gravitating towards idealism (Macleod 2016). 16 For more on Darwin’s influence on Mach, see Pojman (2011, 2019). 17 In saying that all sensory elements are of the same general kind, it must be borne in mind that their specific qualities vary greatly. After all, Mach includes in this general category such different things as colors, light, sounds, tastes, pressures, intensities, times, spaces, motor sensations, and so on. 18 Oddly, there is little or no discussion of percepts and their role in constituting the self in Banks (2002, 2014) or Pojman (2019), both of whom are Mach scholars of the highest distinction. 19 Such issues intersect with the general question of whether, and to what extent, the theory of elements as a whole is concerned with metaphysical matters in addition to its clear epistemological and practical agenda (Hatfield 2015). 20 For example, consider such remarks as these: “As soon as we have perceived that the supposed unities ‘body’ and ‘ego’ are only makeshifts, designed for provisional survey and for certain practical ends (so that we may take hold of bodies, protect ourselves against pain, and so forth), we find ourselves obliged, in many profound scientific investigations, to abandon them as insufficient and inappropriate” (Mach 1910, 11). Note that James was inclined to emphasize this ‘pragmatic’ aspect of Mach’s theory (Klein 2020). 21 Consider his remarks that traditional philosophical problems about the mind can be avoided “if we take the ego simply as a practical unity, put together for purposes of provisional survey, or simply as a more strongly coherent group of elements, less strongly connected with other groups of this kind” (1910, 20–21, second emphasis added). 22 Mill’s resistance to both mental fusions and unobservable egos led him to conclude that the unity of mind brings us “face to face with [its] final inexplicability” (1865, 194). 23 This was also one of the main targets of Ward’s widely-read 1886 encyclopedia entry on psychology (which James cites approvingly) wherein he raised Mill’s worry about self-aware series and deemed the identity of a complex with its components a logical contradiction. 24 James was thus in broad accord with both the ‘Brentano school’ and British ‘realist’ philosophers (such as G.E. Moore and Russell) though he seemingly sided with the latter in denying that mental acts are mediated through contents: “the notion of a real cognition involves an unmediated dualism of the knower and the known” (1885, 142). He also sided with Moore and Russell in denying that the objects of such acts are literal constituents of our mental episodes: “[Cognition] supposes two elements, mind knowing and thing known, and treats them as irreducible. Neither gets out of itself or into the other, neither in any way is the other, neither makes the other. They just stand face to face in a common world, and one simply knows, or is known unto, its counterpart” (1890a, 218). 25 James acknowledged this influence in a 1902 letter to Mach: “I am now trying to build up before my students a sort of elementary description of the constitution of the world as built up of ‘pure experiences’ (in the plural) related to each other in various ways, which are also definite experiences in their turn … I wish you could hear how frequently your name gets mentioned, and your books referred to” (Banks 2014, 88; Klein forthcoming). Also, James owned a copy of Mach’s The Analysis of Sensations (in German) in which he made annotations “clearly aimed at probing the overlaps and divergences between the two men on neutral monism” (Klein forthcoming). 26 I thank Galen Strawson for first bringing such influence to my attention. 27 Despite this, James sometimes professed to being a positivist like Comte, Mill, and Mach (Cooper 2002, 23). Also, it should be noted that he used the term “radical empiricism” at least as early as 1897 (1897, 134). 28 Note that for all citations of James except his 1890 and 1892 works, I include the original year of publication but the pagination from John J. McDermott’s The Writings of William James: A Comprehensive Edition (1977). 29 James already took some steps towards this view as early as his “The Function of Cognition” (1885). 30 In point of fact, James argues that mental acts can involve at least three different kinds of relations: “(1) the self-same piece of experience taken twice over in different contexts,” “(2) two pieces of actual experience belonging to the same subject, with definite tracts of conjunctive transitional experience between them,” or (3) an actual piece of experience and “a possible experience either of that subject or another, to which the said conjunctive relations would lead, if sufficiently prolonged” (1904b, 199–200). Instances of the first, second, and third kinds of mental relations include perception, simple conceptual knowledge, and more complex conceptual knowledge, respectively. 31 James actually articulated something like this view as early as 1894, though he initially describes its character as “idealistic” (1895, 154–58). It should also be noted that there is a great deal of controversy about whether James’s radical empiricism is ultimately a form of panpsychism or panprotopsychism (Lamberth 1999; Cooper 2002; Skrbina 2007; Baily 2020). There is no question that he was at least attracted to such views and saw a very close affinity between them and radical empiricism. 32 James continued: “The holding fast to this relation means taking it at its face value, neither less nor more; and to take it at its face value means first of all to take it just as we feel it, and not to confuse ourselves with abstract talk about it, involving words that drive us to invent secondary conceptions in order to neutralize their suggestions and to make our actual experience again seem rationally possible” (1904b, 198). 33 Interestingly, James arguably changed course in 1909 over worries that reality would be discontinuous if mental chemistry were not in some way possible (1909, 546–57; Skrbina 2007, 147–48). He saw only two options to avoid the discontinuity of emergentism: (1) give up the inherent rationality of reality, or (2) give up the logic of identity. Following Bergson, James opted to take the latter course (1909, 557–61; Lamberth 1999, 179). 34 For James, the essence of “consciousness” is not simply sentience or feeling, but also certain functions and purposes: it is a “fighter for ends” (1890a, 141; Bailey 2020, 68). 35 Russell later published his critique as the second of a three-part series of articles in The Monist entitled “On the Nature of Acquaintance” (1914). 36 There are scholarly debates about whether Russell’s various versions of ‘neutral monism’ were in fact properly so-called. In my view, his ‘neutral monism’ was only partial in his 1919 paper and even in the opening pages of The Analysis of Mind (1921). But there is strong evidence that he fully embraced it by the end of that work. I also think certain aspects of Russell’s neutral monism shifted in important ways around 1940, giving it a character much like so-called ‘Russellian Physicalism’ (Wishon 2015). But for alternative readings, see Banks (2014), Bostock (2012), Landini (2011), Pincock (2018), and Stubenberg (2015, 2017). 37 Russell was almost certainly aware of Mach even earlier as he is discussed in Wundt’s System der Philosophie (1889) and James’s The Principles of Psychology. Russell read the former in 1893 and the latter in 1893 and 1894 (Papers 1, 345–70). Russell later acknowledged Mach’s “fundamental importance” to neutral monism (1921, 22). 38 Russell himself incorrectly credits the term ‘neutral stuff’ to Henry Sheffer (Papers 9, 283). 39 Note, however, that Russell long rejected Brentano’s notion of ‘contents’ intermediate between mental acts and their relevant objects (Papers 7, 44; 1921, 20; 1959, 100–101). 40 Initially, Russell thought it prudent (in psychology’s early state) to assume that some elements are similarly only subject to psychological causal relations and so are solely ‘mental’ (1921, 90–92, 121, 138–39). But over time, he became increasingly confident that all elements bear physical causal relations with each other, and so all ‘mental’ elements are also ‘physical’ (Russell 1958, 12; Wishon 2015). 41 There is a slight complication here for Russell as he (arguably) suggests the causal roles of elements must depend partly on their intrinsic natures or “all the things in the world will merely be each other’s washing” (1927a, 325). 42 Russell’s theory of perception was no doubt guided by his early studies of the psychological theories of Müller, Helmholtz, and Wundt, among others, at Cambridge. 43 For more on Russell’s neutral monist theories of perception and matter, see Wishon (2015, 2020). 44 I would like to thank Galen Strawson, Leopold Stubenberg, Matt Duncan, Daniel Giberman, Timothy Yenter, and Robert Barnard for helpful feedback on this paper. I would like to especially thank Fraser MacBride for his immense editorial patience, without which this paper would not have been completed. REFERENCES Alter Torin , Nagasawa Yujin , eds. Consciousness in the Physical World: Perspectives on Russellian Monism , New York, NY : Oxford University Press . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Bailey Andrew 2020 . “William James, Pure Experience, and Panpsychism,” in Seager, ed. (2020, 66 – 77 ). Banks Erik C. 2003 . Ernst Mach's World Elements: A Study in Natural Philosophy , Dordrecht, Netherlands : Springer Netherlands . Google Scholar Crossref Search ADS Google Preview WorldCat COPAC Banks Erik C. 2014 . The Realistic Empiricism of Mach, James, and Russell: Neutral Monism Reconceived , Cambridge : Cambridge University Press . Google Scholar Crossref Search ADS Google Preview WorldCat COPAC Banks Erik C. 2018 . “Ernst Mach’s Contributions to the Philosophy of Mind,” in Lapointe, ed. (2018, 77 – 95 ). Bode B.H. 1905 a. “‘Pure Experience’ and the External World,” The Journal of Philosophy, Psychology and Scientific Methods , 2 ( 5 ): 128 – 33 . Google Scholar Crossref Search ADS WorldCat Bode B.H. 1905 b. “The Concept of Pure Experience,” The Philosophical Review , 14 ( 6 ): 684 – 95 . Google Scholar Crossref Search ADS WorldCat Bostock David 2012 . Russell’s Logical Atomism , New York : Oxford University Press . Google Scholar Crossref Search ADS Google Preview WorldCat COPAC Brentano Franz 1874 . Psychologie vom empirischen Standpunkt , Leipzig : Dunckner und Humblot . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Brown Robert 1994 . “Comte and Positivism,” in Ten, ed. (1994, 148 – 76 ). Brüntrup Godehard 2017 . “Emergent Panpsychism,” in Brüntrup and Jaskolla, eds. (2017, 48 – 71 ). Brüntrup Godehard , Jaskolla Ludwig , eds. 2017 . Panpsychism: Contemporary Perspectives , New York : Oxford University Press . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Büchner Ludwig 1864 . Force and Matter , trans. Collingwood J. Frederick , London : Trübner . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Clifford C.K. 1878 . “On the Nature of Things in Themselves,” Mind 3 ( 9 ): 57 – 67 . Google Scholar Crossref Search ADS WorldCat Comte Auguste 1853 . The Positive Philosophy of Auguste Comte, trans. Harriet Martineau, in Gardiner, ed. (1969, 133 – 57 ). Cooper Wesley 2002 . The Unity of William James’s Thought , Nashville, TN : Vanderbilt University Press . Google Scholar Crossref Search ADS Google Preview WorldCat COPAC Darwin Charles 1859 . On the Origin of the Species by Means of Natural Selection , London : John Murray . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Darwin Charles 1871 . The Descent of Man, and Selection in Relation to Sex , London : John Murray . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Darwin Charles 1872 . The Expression of Emotions in Man and Animals , London : John Murray . Google Scholar Crossref Search ADS Google Preview WorldCat COPAC Dewey John 1916 . Essays in Experimental Logic , Chicago : University of Chicago Press . Google Scholar Crossref Search ADS Google Preview WorldCat COPAC Eames Elizabeth Ramsden 1967 . “The Consistency of Russell’s Realism,” Philosophy and Phenomenological Research 27 : 502 – 11 . Google Scholar Crossref Search ADS WorldCat Eddington Arthur 1928 . The Nature of the Physical World , Cambridge : Cambridge University Press . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Gardiner Patrick , ed. 1969 . Nineteenth-Century Philosophy , New York, NY : Free Press . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Hartshorne Charles 1937 . Beyond Humanism: Essays in the New Philosophy of Nature , New York : Willett, Clark and Co . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Hatfield Gary 2002 . “Sense-Data and the Philosophy of Mind: Russell, James, and Mach,” Principia 6 ( 2 ): 203 – 30 . Google Scholar OpenURL Placeholder Text WorldCat Hatfield Gary 2004 . “Sense-Data and the Mind-Body Problem,” in Schumacher, ed. (2004, 305 – 31 ). Hatfield Gary 2012 . “Psychology,” in Wood and Hahn, eds. (2012, 241 – 62 ). Hatfield Gary 2015 . “Radical Empiricism, Critical Realism, and American Functionalism: James and Sellars,” HOPOS: The Journal of the International Society for the History of Philosophy of Science 5 : 129 – 53 . Google Scholar Crossref Search ADS WorldCat Heidelberger Michael 2004 . Nature from Within: Gustav Theodor Fechner and His Psychophysical Worldview , Pittsburgh, PA : Pittsburgh University Press . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Huneman Philippe 2012 . “Natural Sciences,” in Wood and Hahn, eds. (2012, 201 – 38 ). Hussain Nadeem J.Z. , Patton Lydia 2016 . “Friedrich Albert Lange,” The Stanford Encyclopedia of Philosophy, ed. Zalta E.N. . Isaac Alistair M.C. 2019 . “Realism without Tears I: Müller’s Doctrine of Specific Nerve Energies,” Studies in History and Philosophy of Science, 10.1016/j.shpsa.2019.01.002 James William 1885 . “The Function of Cognition,” in J. McDermott, ed. (1977, 136 – 52 ). James William 1890 a. The Principles of Psychology, Vol. 1 , New York, NY : Henry Holt . Google Scholar Crossref Search ADS Google Preview WorldCat COPAC James William 1890 b. The Principles of Psychology, Vol. 2 , New York, NY : Henry Holt . Google Scholar Crossref Search ADS Google Preview WorldCat COPAC James William 1892 . Psychology: Briefer Course , New York, NY : Henry Holt . Google Scholar Crossref Search ADS Google Preview WorldCat COPAC James William 1895 . “The Knowing of Things Together,” in J. McDermott, ed. (1977, 152 – 68 ). James William 1897 . “Radical Empiricism: 1897,” in J. McDermott, ed. (1977, 134 – 36 ). James William 1904 a. “Does ‘Consciousness’ Exist?” in J. McDermott, ed. (1977, 169 – 83 ). James William 1904 b. “A World of Pure Experience,” in J. McDermott, ed. (1977, 194 – 214 ). James William 1909 . “The Compounding of Consciousness,” in J. McDermott, ed. (1977, 546 – 61 ). James William 1911 . “Percept and Concept—The Import of Concepts,” in J. McDermott, ed. (1977, 232 – 43 ). James William 1912 . “The Notion of Consciousness,” in J. McDermott, ed. (1977, 184 – 94 ). Jones W.T. 1975 . Kant and the Nineteenth Century , 2nd ed., New York, NY : Harcourt Brace and Company . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Klein Alexander 2015 . “Hatfield on American Critical Realism,” HOPOS 5 ( 1 ): 154 – 66 . Google Scholar OpenURL Placeholder Text WorldCat Klein Alexander 2017 . “Russell on Acquaintance with Spatial Properties: The Significance of James,” in Pincock and Lapointe, eds. (2017, 229 – 64 ). Klein Alexander 2020 . “The Death of Consciousness? William James's Case against Psychological Unobservables,” Journal of the History of Philosophy 58 ( 2 ): 293 – 323 . Google Scholar Crossref Search ADS WorldCat Klein Alexander forthcoming. “Ernst Mach and William James,” in Interpreting Mach: Critical Essays , Preston John , ed. Cambridge : Cambridge University Press . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Lamberth David C. 1999 . William James and the Metaphysics of Experience , Cambridge , Cambridge University Press . Google Scholar Crossref Search ADS Google Preview WorldCat COPAC Landerer Christoph , Huemer Wolfgang 2018 . “Johann Friedrich Herbart on Mind,” in Lapointe, ed. (2018, 60 – 76 ). Landini Gregory 2011 . Russell , New York, NY : Routledge . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Lange Friedrich Albert 1866 . Geschichte des Materialismus und Kritik seiner Bedeutung in der Gegenwart , Iserlohn : J. Baedeker . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Lapointe Sandra , ed. 2018 . Philosophy of Mind in the Nineteenth Century , New York, NY : Routledge . Google Scholar Crossref Search ADS Google Preview WorldCat COPAC Lenin Vladimir 1909 . Materializm i Empirio-Kritisizm , Moscow : Zveno Publishers . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Lovejoy Arthur 1930 . The Revolt against Dualism , Chicago, IL : Open Court . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC MacBride Fraser 2013 . “The Russell-Wittgenstein Dispute: A New Perspective,” in Textor, ed. (2013, 206 – 41 ). Macleod Christopher 2016 . “Mill’s Antirealism,” Philosophical Quarterly 66 ( 263 ): 261 – 79 . Google Scholar Crossref Search ADS WorldCat Mach Ernst 1883 . The Science of Mechanics, trans. T.J. McCormack, in Gardiner, ed. (1969, 385 – 400 ). Mach Ernst 1891 . “Some Questions of Psycho-Physics: Sensations and the Elements of Reality,” The Monist 1 ( 3 ): 393 – 403 . Google Scholar Crossref Search ADS WorldCat Mach Ernst 1905 . Erkenntnis und Irrtum: Skizzen zur Psychologie der Forschung , Leipzig : J.A. Barth . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Mach Ernst 1910 . The Analysis of Sensations , trans. Williams C.M. , Chicago, IL : Open Court . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC McDermott John 1977 . The Writings of William James: A Comprehensive Edition , Chicago, IL : University of Chicago Press . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Mill John Stuart 1843 a. The Collected Works of John Stuart Mill, Volume VII: A System of Logic, Books I–III , ed. Robson J.M. , London : Routledge and Kegan Paul (1974). Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Mill John Stuart 1843 b. The Collected Works of John Stuart Mill, Volume VIII: A System of Logic, Books IV–VI and Appendices , ed. Robson J.M. , London : Routledge and Kegan Paul (1974). Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Mill John Stuart 1865 . The Collected Works of John Stuart Mill, Volume IX: An Examination of Sir William Hamilton’s Philosophy , London : Routledge and Kegan Paul (1979). Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Mill John Stuart 1869 . “Notes to James Mill’s ‘Analysis of the Phenomena of the Human Mind,” in The Collected Works of John Stuart Mill, Volume XXXI , Toronto : Toronto University Press (1989). Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Moleschott Jacob 1852 . Der Kreislauf des Lebens , Mainz : von Zabern . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Moore George Edward 1903 . “The Refutation of Idealism,” Mind 12 : 433 – 53 . Google Scholar Crossref Search ADS WorldCat Müller Johannes 1844 . Handbuch der Physiologie des Menschen , 4th ed., Coblenz : J. Hölscher . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Patton Lydia 2018 . “Helmholtz’s Physiological Psychology,” in Lapointe, ed. (2018, 96 – 116 ). Pincock Christopher 2018 . “Neutral Monism,” in Wahl, ed. (2018, 312 – 33 ). Pincock Christopher , Lapointe Sandra , eds. 2017 . Innovations in the History of Analytical Philosophy , London : Palgrave Macmillan . Google Scholar Crossref Search ADS Google Preview WorldCat COPAC Pojman Paul 2011 . “The Influence of Biology and Psychology upon Physics: Ernst Mach Revisited,” Perspectives on Science 19 ( 2 ): 121 – 35 . Google Scholar Crossref Search ADS WorldCat Pojman Paul 2019 . “Ernst Mach,” The Stanford Encyclopedia of Philosophy, ed. E.N. Zalta, (spring). Reed Edward S. 1994 . “The Separation of Psychology from Philosophy: Studies in the Sciences of Mind 1815–1879,” in Ten, ed. (1994, 297 – 356 ). Rueger Alexander 2012 . “Conceptions of the Natural World, 1790–1870,” in Wood and Hahn, eds. (2012, 169 – 200 ). Russell Bertrand 1895 . “Review of G. Heymans, Die Gesetze und Elemente des wissenschaftlichen Denkens,” Mind 4 ( 14 ): 245 – 49 . Google Scholar Crossref Search ADS WorldCat Russell Bertrand 1912 a. The Problems of Philosophy , London : Williams and Norgate . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Russell Bertrand 1912 b. “Review of James’s Essays in Radical Empiricism,” in Papers 6: 298 – 304 . Russell Bertrand 1914 . “On the Nature of Acquaintance II: Neutral Monism,” The Monist 24 : 161 – 87 . Google Scholar Crossref Search ADS WorldCat Russell Bertrand 1921 . The Analysis of Mind , London : George Allen and Unwin . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Russell Bertrand 1927 a The Analysis of Matter , London : Kegan Paul, Trench, and Trubner . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Russell Bertrand 1927 b. An Outline of Philosophy , London : George Allen and Unwin . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Russell Bertrand 1945 . A History of Western Philosophy , New York, NY : Simon and Schuster . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Russell Bertrand 1948 . Human Knowledge: Its Scope and Limits , London : George Allen and Unwin . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Russell Bertrand 1958 . “What Is Mind?” The Journal of Philosophy 55 ( 1 ): 5 – 12 . Google Scholar Crossref Search ADS WorldCat Russell Bertrand 1959 . My Philosophical Development , London : George Allen and Unwin . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Russell Bertrand 1983 (Papers 1). The Collected Papers of Bertrand Russell, Volume 1: Cambridge Essays, 1888–99 , Blackwell Brink , Griffin Rempel , Slater , eds. London : George Allen and Unwin . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Russell Bertrand 1984 (Papers 7). The Collected Papers of Bertrand Russell, Volume 7: Theory of Knowledge, The 1913 Manuscript , Eames , Blackwell , eds. London : George Allen and Unwin . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Russell Bertrand 1986 (Papers 8). The Collected Papers of Bertrand Russell, Volume 8: The Philosophy of Logical Atomism and Other Essays 1914–19 , Slater , ed. London : George Allen and Unwin . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Russell Bertrand 1988 (Papers 9). The Collected Papers of Bertrand Russell, Volume 9: Essays on Language, Mind and Matter 1919–26 , Slater , Frohmann , eds. London : Unwin Hyman . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Russell Bertrand 1992 (Papers 6). The Collected Papers of Bertrand Russell, Volume 6: Logical and Philosophical Papers 1909–13 , Slater , Frohmann , eds. London : Routledge . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Russell Bertrand 1996 (Papers 10). The Collected Papers of Bertrand Russell, Volume 10: A Fresh Look at Empiricism 1927–42 , Slater , Köllner , eds. London : Routledge . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Seager William 2017 . “Panpsychist Infusion,” in Brüntrup and Jaskolla, eds. (2017, 229 – 48 ) Seager William, ed. 2020 . The Routledge Handbook of Panpsychism , New York, NY : Routledge . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Schopenhauer Arthur 1891 . The World as Will and Idea, Volume I , 3rd ed., trans. Haldane R.B. , Kemp J. , London : Kegan Paul, Trench, Trübner, and Company . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Schumacher , Ralph , ed. 2004 . Perception and Reality: From Descartes to the Present , Berlin : mentis Verlag . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Skorupski John 1994 . “J.S. Mill: Logic and Metaphysics,” in Ten, ed. (1994, 98 – 121 ). Skrbina David 2007 . Panpsychism in the West , Cambridge, MA : The MIT Press . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Skrbina David 2020 . “Panpsychism in the 19th Century,” in Seager, ed. (2020, 53 – 65 ). Small Robin 1994 , “Nietzsche,” in Ten, ed. (1994, 177 – 205 ). Stout G.F. 1889 . A Manual of Psychology , New York, NY : Hinds and Noble . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Strawson Galen 2020 . “What Does ‘Physical’ Mean? A Prolegomenon to Physicalist Panpsychism,” in Seager, ed. (2020, 317 – 39 ). Stubenberg Leopold 2015 . “Russell, Russellian Monism, and Panpsychism,” in Alter , Nagasawa , eds. (2015, 58 – 90 ). Stubenberg Leopold 2017 . “Neutral Monism and Panpsychism,” in Brüntrup and Jaskolla, eds. (2017, 349 – 68 ). Stubenberg Leopold 2018 . “Neutral Monism,” The Stanford Encyclopedia of Philosophy, ed. Zalta E.N. , (fall). Stumpf Carl 1903 . Leib und Seele: Der Entwicklungsgedanke in der gegenwärtigen Philosophie, Zwei Reden , Leipzig : Johann Ambrosius Barth . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Ten C.L. ed. 1994 . The Nineteenth Century , New York, NY : Routledge . Google Scholar Crossref Search ADS Google Preview WorldCat COPAC Textor Mark 2013 . Judgement and Truth in Early Analytic Philosophy and Phenomenology , New York, NY : Palgrave Macmillan . Google Scholar Crossref Search ADS Google Preview WorldCat COPAC Vogt Carl 1845 . Physiologische Briefe für Gebildete aller Stände , Giessen : Ricker’sche Buchhandlung Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Wahl Russell , ed. 2018 . The Bloomsbury Companion to Bertrand Russell , New York, NY : Bloomsbury . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Ward James 1886 . “Psychology,” Encyclopaedia Britannica , 9th ed., Vol. 20 , Edinburgh : Black , 37 – 85 . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Ward James 1899 . Naturalism and Agnosticism: The Gifford Lectures Delivered before the University of Aberdeen in the Years 1896–1898 , London : Adam and Charles Black . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC Wilson Fred 2007 . “John Stuart Mill,” The Stanford Encyclopedia of Philosophy, ed. E.N. Zalta (fall). Wishon Donovan 2015 . “Russell on Russellian Monism,” in Alter and Nagasawa, eds. (2015, 91 – 118 ). Wishon Donovan 2018 . “Russell on Introspection and Self-Knowledge,” in Wahl, ed. (2018, 256 – 85 ). Wishon Donovan 2020 . “Russell’s Neutral Monism and Panpsychism,” in Seager, ed. (2020, 87 – 102 ). Wood Allen W. , Hahn Songsuk Susan , eds. 2012 . The Cambridge History of Philosophy in the Nineteenth Century (1790–1870) , Cambridge : Cambridge University Press . Google Scholar Crossref Search ADS Google Preview WorldCat COPAC Wundt Wilhelm 1889 . System der Philosophie , Leipzig : Wilhelm Engelmann . Google Scholar Google Preview OpenURL Placeholder Text WorldCat COPAC © The Author(s), 2021. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)
TI - Radical Empiricism, Neutral Monism, and the Elements of Mind
JF - The Monist
DO - 10.1093/monist/onaa026
DA - 2021-01-19
UR - https://www.deepdyve.com/lp/oxford-university-press/radical-empiricism-neutral-monism-and-the-elements-of-mind-WIxakTF6zQ
SP - 125
EP - 151
VL - 104
IS - 1
DP - DeepDyve
ER -