What does “physical” mean? A prolegomenon to panpsychism [revised]

[revised version of the chapter in The Routledge Handbook of Panpsychism (2020), forthcoming in Mind and Being] What does “physical” mean? A prolegomenon to panpsychism ‘Panpsychism must be considered a species of naturalism’ R. W. Sellars (1927: 218) ‘Panpsychism … is only a revised materialism’ C. A. Strong (1930: 327) 1 Introduction Philosophy is plagued by the fact that different people use the same words in very different ways. The misunderstandings that result are often calamitous, for a reason clearly stated by Mary Shepherd: … every one must be conscious that the particular forms of expression, in which thoughts of an abstruse and subtle nature are introduced to the imagination, and grow familiar there, are so intimately associated with them, as to appear their just and accurate representative. But these forms of expression, though clear and satisfactory to the person in whose mind they are so associated, may yet fail in conveying the same ideas with sufficient precision to the understandings of others.1 All too often, philosopher A can’t hear what philosopher B is saying because A can’t help hearing B’s words as meaning something different from what B is using them to mean. Many of us have had the experience of re-reading a piece of philosophy and realizing that the reason we disagreed with it the first time we read it was simply that we were closed to the way its author was using certain words. It’s widely agreed that terminological problems are acute when it comes to the discussion of mind. I’m going to make some proposals about how we may best use certain words, proposals that will constantly raise substantive matters. 2 Panpsychism and psychism Panpsychism is the view that mind or consciousness (psyche) is present in all (pan) reality. In its strongest form, pure panpsychism, it’s the view that mind is all there is to reality: mind is the stuff of reality, the (‘categorical’) stuff being of reality. Eddington puts it plainly: ‘the stuff of the world is mind-stuff’ (1928: 276). Drake says the same: 1 1824: vi. When I cite a work I give the date of first publication, or sometimes the date of composition, while the page reference is to the edition listed in the bibliography. In the case of quotations from languages other than English I give a reference to a standard translation although I don’t always use precisely that translation. psychic stuff is the very stuff of which the world is made; and while everything is subject to physical law, everything is made of the very stuff of which we ourselves—with our inner mental being—are composed (1925: 89). According to the panexperientialist version of pure panpsychism, consciousness, or experience, or experiencing, or experientiality, is all there is to reality (it is all there is to mind).2 Whitehead puts it plainly: ‘apart from the experiences of subjects there is nothing, nothing, nothing, bare nothingness’.3 It’s worth saying straight away that there’s no conflict between panexperientialism and anything true in physics. For while physics tells us a great deal about structural-relational features of reality, it has little to say about the intrinsic structure-transcendent nature of the stuff that has the structure (see §10)—where by ‘stuff’ I simply mean whatever it is (however insubstantial-seeming or fundamentally processual in nature) that gives the structural-relational features of reality their concrete existence. Physics is wholly open to the possibility that the intrinsic nature of the shimmering stuff it posits is consciousness or experientiality.4 Panexperientialism is accordingly wholly compatible with materialism, when materialism is properly understood (see §4). This point was well understood in the first half of the last century. Since then it has been largely lost from sight, partly for terminological reasons of the sort I aim to address in this chapter—to the point where many now find it preposterous, in a way that Shepherd would find wholly unsurprising. It is a cast-iron point, but it has become very hard for some to see. A weaker form of panpsychism holds that while mind or consciousness—experience or experiencing or experientiality—is present in all of reality, it isn’t all there is. The Oxford English Dictionary defines panpsychism in this weaker way as the view that ‘there is an element of consciousness in all matter’. There’s good reason to think that panpsychism is the most plausible view of the fundamental nature of reality—where by ‘reality’ I mean concrete reality, everything that exists in the universe.5 What’s the next most plausible view? One might call it psychism, although the name isn’t ideal. Psychism is panpsychism without the ‘pan’. It’s the view that while mind/consciousness/experience/experientiality is one of the fundamental features of reality (like, say, electric charge), it isn’t all there is. I won’t go on repeating ‘mind or consciousness or experience or …’. From now on I’ll often simply use ‘experience’, by which I’ll always mean conscious experience (I take it that there isn’t any other kind), although I’ll also use ‘consciousness’ or ‘experientiality’. 2 As far as I know the term ‘panexperiential’ was introduced by Griffin (1977). See also Shields (2001). Basile notes that Whitehead’s view ‘would indeed be better called “physicalist panexperientialism” (or … “panexperientialist physicalism”), rather than “panpsychism” or “panexperientialism” tout court’ (2017: 71). 3 1927–8: 167. Note that to say this is not to say or imply that subjects are ontologically distinct from experiences. 4 By one estimate, 700 billion solar neutrinos pass through one’s brain every second. 5 ‘Concrete reality’ contrasts with ‘abstract reality’: some hold that numbers and concepts are real things, part of reality, but are abstract entities rather than concrete entities. One quick way to characterize concrete reality is to say that to be concretely real is to be capable of entering into causal relations. Here I put aside questions about abstract reality and usually speak simply of ‘reality’. 3 Pure panpsychist materialism What exactly do I mean by ‘experience’ or ‘consciousness’? I mean what most people mean in the current debate. I’ll say more in §7. Before that I want to note one of the most implausible views of the fundamental nature of reality. This is the view held by many (I think most) in the West today, the view that psychism (and a fortiori panpsychism) is certainly false—that experience certainly isn’t one of the fundamental features of reality. Those who endorse this last view have to hold either that (i) experience doesn’t really exist at all—that it is an illusion— or (ii) experience somehow ‘emerges’ from stuff that is in its fundamental nature wholly and utterly non-experiential. Like many, I don’t think (ii) is tenable, because it requires that something known as radical emergence takes place in nature. Few, however, will deny that it looks preferable to (i). So it’s striking that many philosophers, unable to accept panpsychism or psychism, have in the last sixty years or so chosen (i) over (ii). These philosophers standardly deny that they’ve chosen (i), even as they commit themselves to claims that do in fact entail (i), and this denial, at least, is not surprising, because (i)—which is also known as eliminativism about experience or consciousness—is I believe the silliest view that has ever been seriously held by any human being. You may wonder who these philosophers are. They include (for a start) all genuine philosophical behaviourists, all those who genuinely endorse functionalism in the philosophy of mind, and some if not all of those who now call themselves ‘strong representationalists’. Nearly all of them deny that they’re eliminativists about consciousness, as remarked; they say that they offer ‘reductions’ of the experiential to the non-experiential, and that reduction is not elimination. But reduction is elimination in certain cases. All these so-called ‘reductions’ of experience amount to the denial of its existence, in any honest accounting, simply because they propose to reduce experience to something that it obviously is not (see Strawson 2018). I need to say more about radical emergence, and about words like ‘mind’ and ‘experience’. First, though—this topic is like a jigsaw puzzle—let me specify the kind of panpsychism I’ll focus on for the sake of argument. I’ll call it pure panpsychist materialism, PPM for short, and concentrate on its panexperientialist version: panexperientialist materialism. According to PPM, the physical world is wholly constituted of experience (even subjects of experience are nothing ontologically over and above experiences). As far as I can see, Strong, Drake and Eddington are pure panpsychist materialists, along with Whitehead, Sprigge, and many others, including, arguably, James (see e.g. Strong 1918, 1930, Drake 1925, Whitehead 1925, Eddington 1928, Sprigge 1983, James 1909). Russell is open to the idea that it is true, and constantly stresses the point that there must be some fundamental continuity—i.e. homogeneity—of nature between the conscious experience with which we have immediate acquaintance and the rest of concrete reality (1927a, 1927b, 1948, 1956, 1959). More recently, Sprigge (1983) and Griffin (1998) stand out among panexperientialist materialists.6 4 Stuff To be a materialist or physicalist7 is simply to hold that everything that concretely exists is wholly physical. (I start trying to say what it is to be physical in §9.) PPM is materialist by definition, and it’s straight-up realist about everything that comprises what we ordinarily think of as the physical world: clouds, brains, chairs, mountains, and all the entities and qualities whose existence physics is right to recognize, quarks, say, or charge, or fields.8 It has nothing to do with idealism in the Berkeleyan sense of the term (Berkeley 1710), according to which ‘physical objects’ are ideas in minds. PPM leaves the universe wholly independent of our minds—except for those parts of it that are our minds. So too it leaves everything true in physics wholly in place, as remarked. Panpsychism has no quarrel with physics because it offers an answer to a question about concrete reality about which physics, strictly interpreted, has little or nothing to say. Quine makes the key point: when it comes to the denoting terms of physics, ‘reference [can] be wildly reinterpreted without violence to evidence’ (1992: 9). The question is What is the ultimate, intrinsic, categorical nature of the stuff that exemplifies the structures that physics discerns and captures in its equations? PPM answers: the ultimate, intrinsic, categorical nature of physical stuff is experience, experientiality.9 Most present-day materialists assume that the ultimate or fundamental intrinsic nature of physical stuff is non-experiential, and they further assume that this assumption is an essential part of materialism. The first assumption has no obvious warrant in physics, however, and the second is therefore doubtful. If one puts aside the standard use of the term ‘energy’ in physics to denote the power of doing work possessed by a body or system of bodies, one can adopt Heisenberg’s large metaphysical use of the term when he says that ‘energy is a substance’, and that ‘all 6 See also Hartshorne (1936, 1942). For some more recent discussion, see Nagel (1979, 2012: 54–8), Seager (1995, 2016), McHenry and Shields (2016). For a survey, see Skrbina (2005). I endorse ‘psychism’, although not under that name, in Strawson 1994 (e.g. pp. 60–2). 7 I follow D. C. Williams (1944: 418) and David Lewis (1994: 293) in treating these two terms as equivalent, and giving priority to the traditional term ‘materialism’, although there is in fact more to the physical than matter. 8 ‘Fundamental particle’ is a misleading term, given quantum field theory, but terms like ‘quark’ and ‘electron’ do pick out concretely real phenomena, and it’s often useful to talk in terms of particles. 9 I’m hoping to avoid a nest of disputes by piling the terms ‘ultimate’, ‘intrinsic’ and ‘categorical’ on top of each other. I should say that I take it (contrary to some widespread terminological habits) that there’s a fundamental sense in which potencies or power properties are correctly said to be categorical properties, i.e. actual properties, properties that are always there, constitutive of the being of the thing whose potencies they are (they do not have a ‘merely dispositional’ existence). As Cavendish says: ‘body cannot quit power, nor power the body, being all one thing’ (1664: 98). See also Locke (1689–1700: §2.8), Heil and Martin (1998), Strawson (2008), Heil (2012: ch. 4). particles are made of the same substance: energy’.10 On this view, concrete stuff isn’t well thought of as something that is distinct from energy and that has energy. Rather concrete physical stuff is energy. This is one way to make a first step towards PPM.11 Given that concrete physical stuff = energy, we can ask the following question: What is the fundamental intrinsic structure-transcendent nature of this energy, this energy stuff? Physics doesn’t say (see §10). We face the question whether it is non-experiential or experiential. PPM points out [1] that we know for certain that there is experientiality, [2] that we don’t know for certain that there is any non-experiential reality, [3] that we have very strong reason to expect fundamental continuity of being or nature between the experiential reality we know for certain to exist and any other concrete reality there is, [4] that to suppose that the fundamental intrinsic nature of reality is wholly non-experiential requires one to posit ‘radical’ emergence of the experiential from the non-experiential. In the light of this it proposes that the most natural and parsimonious hypothesis is that all concrete reality is experiential. On this view, then, experientiality is a kind of stuff: stuff = energy = experientiality. If reality is indeed spatiotemporal, then experientiality is spatiotemporal in exactly the same way as we ordinarily suppose non-experiential stuff to be. It may be said that a thing has to have some sort of non-experiential stuff being in order to be spatial, and hence spatiotemporal. This is one potent source of resistance to PPM. In §11 I’ll argue that it’s misguided. As with any stuff, one can wonder how much experientiality there is. We know there’s a lot on this planet—human, elephantine, leonine, canine, feline. We may wonder how much more there is in the universe. Most people think there isn’t any on the moon. They’re wrong if any form of panpsychism or psychism is true, but they’re very probably right that there isn’t any biologically evolved experientiality on the moon.12 If experientiality is the whole stuff of reality, as PPM proposes, or even if it is only one fundamental feature of reality, as psychism proposes, then almost none of it is biological (I’ll use ‘biological’ to cover all forms of evolved experientiality). When evolution gets going it works physical stuff (= energy = experientiality) into wonderfully complex experiential forms, e.g. animal vision, smell, and hearing, just as it works physical stuff (= energy = experientiality) into wonderful spatial forms, e.g. the eagle spatial form or the human spatial form (opposable 10 Heisenberg 1958: 63, 71. Compare Smart, who, defining and endorsing materialism, writes that ‘energy counts as matter for my purposes’ (1963: 651). 11 So too, concrete physical stuff isn’t well thought of as something that is in some way distinct from process, in which processes go on or occur; it is process. So too, concrete stuff isn’t something that possesses certain natural, categorical, concretely instantiated intrinsic qualities while being in some manner irreducibly ontologically distinct from them; its existence is nothing ontologically over and above the instantiation of those qualities. It is, however, hard for us to hold this point steadily in mind given the deep objectproperty/subject-predicate structure of our thought and language. 12 In this case there is no mind on the moon, in the Russell-James sense to be explained in §8 below—even if there is experientiality or feeling/sentience or consciousness in the most common present-day sense of ‘consciousness’. This distinction between mind and consciousness, which is found in some of the principal writings on this topic, is a major terminological pitfall, because we take it today that consciousness entails mind. Another lies in the essentially cognitive-relational sense of ‘consciousness’ favoured by many in the early twentieth century, which has the consequence (directly contrary to standard present-day use) that sentience, in the maximally general sense of feeling of any sort (which does not presuppose sense organs), is not sufficient for consciousness. thumbs and all). Another potent source of resistance to PPM may be expressed as follows. [1] The power being of stuff is (as Locke says) wholly grounded in—in fact nothing over and above—the categorical being of stuff.13 [2] It seems natural at first to think that there is far more difficulty in supposing that all the power being that we find in concrete reality is grounded in experiential categorical stuff than in non-experiential categorical stuff. The principal reason for this, perhaps, is that [3] we find it extraordinarily difficult, when we think of these things, to factor in a proper appreciation of the extent to which what we apprehend as the physical world is an appearance—not only in our everyday life but also when we are doing physics and taking it (as we naturally and mistakenly do) that in doing physics we are apprehending the nature of physical stuff in some way that goes beyond our apprehension of the equations of physics. We have forgotten Kant, or if you like the neo-Kantian correction of Kant. We are as Russell said constantly ‘guilty, unconsciously and in spite of explicit disavowals, of a confusion in [our] imaginative picture of matter’ (1927a: 382). The problem is compounded by the fact that we (many of us) tend to think we know what experientiality is in such a way that we know that it couldn’t possibly ground all the power being that we see running the world, alive in the world (as it were).14 Kant makes point [1] as follows in a ‘pre-critical’ text— every substance, including even a simple element of matter, must … have some kind of inner activity as the ground of its producing an external effect, and that in spite of the fact that I cannot specify in what that inner activity consists (1766: 315, Ak. 2.328) —and adds an intriguing footnote about point [2]: Leibniz said that this inner ground of all its external relations and their changes was a power of representation [nb this power is an inner activity]. This thought … was greeted with laughter by later philosophers. They would, however, have been better advised to have first considered the question whether a substance, such as a simple part of matter, would be possible in the complete absence of any inner state. And, if they had, perhaps, been unwilling to rule out such an inner state, then it would have been incumbent on them to invent some other possible inner state as an alternative to that of representations and the activities dependent on representations (ibid.) 13 Locke expresses this basic metaphysical point, which he shares with Descartes, and which is now sometimes called the ‘powerful qualities’ view, in an exemplary fashion (1689–1700: §2.8). Its occlusion is one of the catastrophes of modern metaphysics. One mistake (see note 7 above) is to think of power being as ‘merely dispositional’ in a way that forces one to oppose it to categorical being. In fact power being is essentially something live, active, categorical. (It’s because ‘particles’ are essentially dynamic entities, always humming away, as it were, that they can and do do what they do). Another mistake is to think of the categorical being of stuff in a ‘staticist’ and ‘separatist’ manner—as if it could be what it is independently of the laws of nature that are in fact essentially constitutive of its nature. 14 It is perhaps the sense that experientiality just hasn't got the resources (clout, oomph) to ground all the power being of the world that leads Goff to argue for a version of panpsychism in which there is ‘consciousness+’ in addition to basic consciousness = experientiality (see Goff 2017: 179ff). Compare Sellars 1932: 420: ‘a brain-state is for me conscious content plus’.) Although I think this way of putting things is useful, I don’t think we have good reason to suppose that we know enough about experiential stuff to know that it is less well fitted than non-experiential stuff to ground, or rather be, the power being of the world. To know the nature of experience just in having it is not ipso facto to know its power being, in the sense of the effects it is disposed to have on other things. See further Mørch 2017. The point is simple: it's not clear that we have any good reason to think we know anything about concrete reality that favours the view that non-experiential stuff is better than experiential stuff as (a ground for) the power being of the world. It’s quite unclear that physics favours this view (§§10,12). It’s worth adding this. When we think of the physical world in the standard nonexperiential way, we easily allow that leptons and quarks jointly constitute larger things that have intrinsic, natural, categorical properties that are essentially more and other than the intrinsic, natural, categorical properties of leptons and quarks. So too, when we switch to thinking of the physical world in a non-standard, panpsychist way as constituted of experientiality, we may allow that non-biological experiential entities like leptons and quarks jointly constitute larger things (e.g. biologically evolved experiences) that have properties that are essentially more and other than the (experiential) properties of leptons and quarks. 5 Unity We may do this even if we continue to conceive of leptons and quarks in a crude ‘smallist’ way as genuine individuals of some sort. We do better, though, to conceive of them in a quantum-field-theoretic way, as features or aspects of the various ‘fields’ that jointly constitute the universe in a way that is profoundly mysterious to us, or (perhaps better still) as features or aspects of the single complex field that constitutes—is—the universe, and is perhaps not ultimately ontologically distinct from space–time.15 A further point in this vein. It seems we must allow the interconnection of everything (‘pick a flower on Earth and you move the farthest star’—a remark attributed to Paul Dirac) and the deep (non-trivial) sense in which the universe is a single thing. At the same time, quantum field theory has no difficulty with the fact that things like animals, stones, bottles, and aeroplanes present as individual entities that are in some very fundamental manner ontologically distinct from other such entities—even though they’re all wholly constituted by changing energy levels in the set of vibratory motions in fields—and I can see no good reason to think that quantum field theory will have any more difficulty with the fact that subjects of experience like ourselves present as individual entities that are in some fundamental manner ontologically distinct from, closed off from, other such entities.16 ‘No. The cases are quite different. The distinctness or individuality of the bottles and aeroplanes is really just an appearance, an appearance to a subject of experience whose distinctness or individuality can’t be just a matter of appearance—appearance to itself.’ There is, I think, no real difficulty here. First, it seems that the unity of a planet orbiting 15 What we have are particle-like appearances, produced by changing energy levels in the set of vibratory motions in fields, that are not well thought of as persisting things. ‘Particles … are emergent entities in modern physics … the popular impression of particle physics as about the behavior of lots of little point particles whizzing about bears about as much relation to real particle physics as the earth/air/fire/water theory of matter bears to the Periodic Table’ (Wallace 2013: 220). 16 ‘The breaches between [experiences] belonging to different … minds’, in James’s words, ‘are the most absolute breaches in nature’ (1890: 1. 226). a star—an aeroplane in flight, a person walking along a road—must be allowed to be a genuine functional unity in some sense given which the unity cannot be said to be ‘just a matter of appearance’; even if there is a respect in which it’s true to say that all there are in the end are vibratory motions in fields. Second, there’s no reason to suppose that the seeming individuality of a single experience or single mind is not something of the same sort, a genuine functional unity that is, as such, not just a unity-appearance. Suppose we represent the various fields (or single complex field) that arguably wholly constitute (or constitutes) concrete reality pictorially, as a great flexible grid. Human (and other biological) subjects of experience may then be depicted as local peaks or bulges in the grid. To be an experiential peak of this sort is to experience one’s consciousness as essentially bounded or isolated even though it’s essentially part of the great interconnected weave. It is in fact essential to one’s biologically evolved consciousness having the adaptive function it does, located as it is in a body that constitutes (operates as) a genuine unity in some sense that is not undercut by the field-theoretic view of reality, that it have the character of being experience from a single point of view; i.e. that it be experience from a single point of view. There is more to say. One may think also of plants that genuinely distinct although rhizomatically connected (one may think of ātman and brahman). Many accounts have been given of how individual biological experiential fields like our own may have the closed character they do even if they are in some sense just aspects or ‘modes’, in Spinoza’s terminology (Spinoza 1677), of some larger field. The present aim is simply to propose that there is no fundamentally greater difficulty in what one might call the singleness or unity features of subjects of experience than there is in the singleness or unity phenomena of things like planets and bottles.17 6 Why materialist panpsychism? ‘Look, I understand that you might perhaps want to defend panpsychism, even pure panpsychism, but why on earth do you want to defend pure panpsychist materialism, PPM? How can one possibly claim to be both a materialist (or physicalist) and a panpsychist?’ Well, this is an attempt to explain how one can do this and why one might want to. David Lewis and Bertrand Russell are immediately helpful. Lewis points out that “a thesis that says [that] panpsychistic materialism …is impossible … is more than just materialism” (1983: 36), rebuking those who think that materialism (or physicalism) and panpsychism are mutually incompatible. Russell makes a related point when he notes that common sense leaves us completely in the dark as to the true intrinsic nature of physical objects, and if there were good reason to regard them as mental, we could not legitimately reject this opinion merely because it strikes us as strange. The truth about physical objects must be strange (1912: 19). In later writings he adds that science—physics—also leaves us in the dark in this way: 17 I take it that planets and bottles are not also subjects of experience, and I know of no panpsychist who thinks that all collocations of subjects of experience are subjects of experience. Football teams aren’t subjects of experience any more than bottles are. physics is mathematical, not because we know so much about the physical world, but because we know so little (1927b: 125). So far, then, and as already remarked, the way is wide open to PPM——a point widely understood in the first half of the twentieth century. It may be added that panpsychism has traditionally been understood to be a form of materialism, as in the Oxford English Dictionary definition already quoted: it’s ‘the theory or belief that there is an element of consciousness in all matter’. 7 Terminology 1: ‘experience’, ‘experientiality’ I’m now going to define and comment on a few terms and declare some assumptions. I’ll continue to shunt certain details into footnotes designed for those who already have some familiarity with these issues. I can’t hope to defend all the philosophically controversial things I will say in doing this—even putting aside the fact that everything is controversial in philosophy. This paper is at best a prolegomenon to panpsychism. Most of the work it aims to do lies in the following definitions and comments. So to begin. By ‘experience’ (used as a mass term with no plural) or ‘experientiality’ I mean what many today in philosophy mean by ‘consciousness’. In more complicated vocabulary, I mean concretely occurring experiential ‘what-it-is-likeness’, phenomenological ‘what-it-is-likeness’, however simple or primitive, considered just as such. I mean subjective experience with a certain qualitative character that is private in the straightforward and unexceptionable sense that it is directly known only to the creature that is having it. Our own experience affords us clear examples of this sort of ‘what-it-islikeness’: colour experience, thought experience, pain, fear, anxiety, amusement, and so on. These examples suffice to convey the idea of what experience is in a completely general manner that allows us to grasp the thought that there may be (and surely are) forms of experience that we cannot imagine, including, perhaps, or no doubt, the most primitive forms of experience. It also gives us the resources to suppose (in the way sketched at the end of §4) that our own complex biologically evolved experiences may be manifestations or effects or fusions of other experiential phenomena of which we have no from-the-inside knowledge.18 ‘Phenomenological what-it-is-likeness considered just as such’: the words ‘considered just as such’ are important. They’re designed to limit the meaning or reference of the words ‘experience’ and ‘experientiality’ strictly to the concretely occurring experiential character—the immediately given phenomenological19 content or character—of conscious mental episodes, while excluding any reference to anything else that may exist, including anything else on which the existence of such character or content may be thought to 18 There are various ways of sketching how this comes about. See e.g. Seager 2010, 2016; see also Mørch 2014, Turausky MS. See also James 1909 (ch. 5 ‘The Compounding of Consciousness’), Strong 1918: , Drake 1925: 98–100. 19 What is immediately phenomenologically given may be highly complex and conceptually rich, as it is usually is in our own case. See e.g. Montague (2016), Siegel (2017). depend.20 Experience is always and necessarily experience of or about something, simply because it necessarily has some experiential/phenomenological content or ‘what-it-is-likeness’ or other, and it is always (and trivially) experience of that, whatever else it is or isn’t experience of. In the limiting case it isn’t experience of anything else at all. There needn’t, for example, be anything red in concrete reality, over and above the kind of redness that may be truly said to be instantiated in the conscious occurrence of the red-experience itself, in order to for there to be red-experience.21 I’m an all-out, out-and-out realist about experience, a real realist about experience. I take it that we know what experience is simply in having it, because the having is the knowing. (This may help some to understand what I mean by ‘experience’: it’s that of which it is true to say that the having is the knowing.) We not only know exactly what particular kinds of experience are, simply in having them. We also know what experience is quite generally considered, simply in having experience of certain sorts, because, again, the having is the knowing. A five-year-old child knows as well as anyone else what it is. Suppose five-year-old Lucy is facing the sun with her eyes closed and eating a sweet. If we ask her whether she likes the taste, and what colour she is experiencing, she’ll know exactly what we mean and find it easy to answer. In the last century philosophers have managed to turn this simple matter into a conceptual Mordor, but we can ignore them. The real ‘mind–body problem’ begins only when one endorses real, out-and-out, everyday realism about experience. To do anything else is to refuse to face the problem, as many who call themselves ‘materialists’ do today.22 All serious materialists, all real or genuine materialists, as I like to say, are realistic materialists. They are in other words materialists who, like almost all materialists for well over two thousand years (until about 1960), are real realists about experience. The idea that materialism might or does lead to the denial (covert or overt) of the existence of consciousness or experience is very recent. As far as I know, no one before the twentieth century was foolish enough to entertain it. 8 Terminology 2: ‘mental’, ‘mind’ 20 This is another point at which misunderstanding is possible—and likely, given a hostile reader. Suppose that someone takes experientiality as just defined to be an intrinsic feature of a complex event e that also essentially has non-experiential intrinsic features (many think in this way when they suppose that experiences are neural goings-on), The point is then that the words ‘experience’ and ‘experientiality’ as used in this paper refer only to the experientiality of e and do not refer even indirectly to any supposed non-experiential being. This ruling may be felt to clash with a picture of things according to which the experiential and the nonexperiential are somehow identical. It does, but this is a good thing, because the picture is incoherent—a simple point that explains why Sprigge says that ‘anything going for the identity theory’, i.e. the mind-brain identity theory, ‘is evidence for the truth of panpsychism, as was realized long ago by philosophers such as Josiah Royce’ (1983: 102). There is a deep thought-bog here (I speak from painful past experience of embogment). 21 There is as Pautz has remarked a primordial sense in which ‘colors live only in the contents of our experiences’ (2009: 60). To this extent, the old and confident protest that experiences of red aren’t themselves red is too quick. We can give a good account of the sense in which redness as we ordinarily and naively conceive of it is an essentially experiential matter. 22 For an account of how Lewis does this, see Strawson 2019: §4. I take the words ‘mental’ and ‘mind’ to cover the whole range of things that are ordinarily taken to be mental, from the most complicated thoughts about algebraic topology to the simplest possible feeling experience, the simplest occurrence of which it is true to say that there’s ‘something it is like’, experientially, to have it. According to this definition all experience is mental, and my concern in this paper is only with the experiential. It is, however, very important to be aware that some philosophers use ‘mind’ and ‘mental’ in an essentially narrower and more exclusive sense, according to which ‘mere’ or ‘bare’ feeling, primitive experiential what-it-is-likeness, does not count as mental. Russell, for example, standardly takes it that some sort of cognitive and mnemic (memory) capacity is a necessary condition of mind or mentality, and accordingly classifies mere or bare feeling/sentience as not intrinsically mental. This allows him to say that he is a neutral monist, someone who thinks that the fundamental stuff of reality is stuff of a single kind that is neither mental nor physical, even as he proposes that ‘sensations’ are the fundamental stuff of reality—things that we today ordinarily classify as paradigmatically mental. Something similar is true of James when he declares himself to be a neutral monist while holding that the fundamental stuff is ‘pure experience’—something that we today ordinarily classify as paradigmatically mental.23 Drake also holds that mind entails cognition, and takes it accordingly that there can be essentially ‘psychic stuff’ (1925: 91) without mind. So too Strong ( There’s a parallel point to be made about the word ‘conscious(ness)’. I use it here in a currently standard inclusive way according to which any sort of feeling or experiential what-it-is-likeness, however primitive, is conscious. Russell, James, Strong, Drake, and many others use ‘consciousness’ to mean something essentially more complex, something that is essentially intentionally of something other than its immediately given phenomenological character, and essentially cognitive in that sense. It is, to repeat, extremely important to be aware of these different usages, especially when reading earlier twentieth-century work. The terminological terrain is treacherous. In this paper I’ll continue to use ‘mind’, ‘mental’, and ‘conscious’ in the inclusive way according to which any sort of experiential what-it-is-likeness, however primitive, is correctly called ‘mental’ and ‘conscious’. Unlike James and Russell, therefore, I will accept [feeling → conscious] and [experiential → mental].24 We all accept [conscious → mind], but for different reasons: they because they have more restrictive notions of both mind and consciousness, as just described, I because I have more inclusive notions of both. One has to learn to navigate these differences in order to 23 I think this is the best way to take Russell’s and James’s neutral monism if one reads them in a more or less straightforwardly metaphysical way. There is, however, disagreement about how to read them (see in particular Wishon 2015, Stubenberg 2016), and one must never forget that both are strongly driven by epistemological considerations of a radical empiricist kind. These lead Russell to say that both mental and physical entities are ‘constructions’, ‘logical constructions’ out of sensations, and, as constructions, can’t be the basic stuff (James holds a similar view but substitutes ‘pure experience’ for ‘sensations’). The fact remains that the ‘material’ out of which the mental and physical is constructed (‘sensation’ or ‘pure experience’) counts as mental on most views, as do the ‘raw feels’ Tolman uses to characterize Russell’s view: ‘raw feels may be the way physical realities are intrinsically, i.e., in and for themselves’ Tolman (1932: 427). 24 I use ‘→’ to mean ‘metaphysically entails’. draw effectively on the resources of the true zenith of discussion of the mind–body problem in the Western philosophical tradition (the period from about 1870 to 1950, before the following nadir c. 1960 to the present day). 9 Terminology 3: ‘physical’, ‘materialism’ (‘physicalism’) The definition of the words ‘physical’ and ‘materialism’ (or ‘physicalism’) is particularly important. Much of the confusion in the current discussion of the ‘mind–body problem’ stems from the fact that different philosophers use these words in a number of different ways. (I suspect that this problem will never be remedied, as succeeding generations pile enthusiastically into the debate and lock on to one use or another.) I take it, to begin, and entirely uncontroversially, that [a] [x is physical → x is concrete] and [b] [x is physical → x is the subject matter of physics]. [b] states that the physical is what physics is actually talking about, what is actually referred to in or by physics, however wrong physics is about the physical, and however limited the descriptive powers of physics are when it comes to the physical. There is as already remarked a fundamental respect in which these descriptive powers are extremely limited (see further below). As a materialist, I also take it that [c] [x is found in our universe → x is physical] and that [d] [x is physical → x is physics-tractable] where by saying that something x is ‘physics-tractable’ I mean something quite rich— roughly that our physics doesn’t just talk about x but is capable of getting quite a lot right about its nature, and does in fact get quite a lot right about its nature.25 I take it that [b] and [c] are enough to fix the reference of the term ‘physical’ while (rightly) leaving fundamental questions about the nature of the physical as yet undetermined. I will also take it that [e] [x is physical → x is a spatiotemporal entity] 25 Note for philosophers of science: I take it that physics gets quite a lot right in a way that is not only compatible with the truth of PPM but also with Laudan’s ‘pessimistic induction’ (Laudan 1981). and indeed that [f] [x is physical ↔ x is spatiotemporal] while noting, first, that a number of physicists think that space–time is not a truly fundamental feature of reality, and, second, that there appear to be fundamental things that we don’t understand about the nature of space–time. Given these two points, I’m going to treat ‘space–time’ as a proper name for whatever is in fact the fundamental dimensionality of concrete reality, and mark it as such with an asterisk: ‘space–time*’. I take it as given—a priori—that concrete reality must have some dimensionality or ‘existence-room’ (Existenzraum) or other, which I’m now calling ‘space– time*’. At the same time, I take it—along with certain leading cosmologists—that there may be no real distinction between what the existence of the (stuff of the) universe consists in and what the existence of (what we think of as) its dimensionality consists in. Steven Weinberg’s characterization of a version of string theory is one vivid illustration of this idea: on this view the fundamental entities currently recognized in the standard model of physics are not strictly speaking fundamental and are to be explained as ‘various modes of vibration of tiny one-dimensional rips in space–time known as strings’ (1997: 20).26 With these provisions, ‘space–time*’ and its adjective ‘spatiotemporal*’ denote the actual dimensionality of concrete reality even if (even though) we are in various ways wrong about or ignorant of its nature. [e] and [f] emerge as trivially true given this ruling, but there’s no harm in that—no harm in having [f] listed as an explicit condition of physicality. (One could simply name the actual dimensionality of our universe ‘D’, and to use ‘D’ as adjective and noun to replace ‘spatiotemporal’ and ‘space–time’.) Plainly to be a materialist is also to hold that [g] [x is experience and is in this universe → x is physical], and to be a real materialist, in my present terms, is to be a real realist (a five-year-old Lucy realist) about experience. It’s to hold that ‘the heady luxuriance of experience’, ‘experience in all its richness’, in Quine’s robustly realist words (1981: 185),27 is wholly physical in 26 In the classic debate about space and time between ‘substantivalists’ and ‘relationalists’, some ‘substantivalists’ think of as space a pure container of stuff that is in itself stuffless, relative to the stuff it contains, so they’re not substantivalists in the present sense. 27 Quine the great naturalist never denied the existence of (real) experience, as some self-styled ‘naturalists’ now feel they need to do. Compare Maxwell, when he characterizes his own physicalism ‘as a nonmaterialist physicalism. It is nonmaterialist in that it does not attempt to eliminate or in any way deemphasize the importance of the ‘truly mental’. On the contrary, it accords central roles to consciousness, ‘private experience’, subjectivity, ‘raw feels’, ‘what it’s like to be something’, to thoughts, pains, feelings, emotions, etc., as we live through them in all of their qualitative richness. The theory also claims, however, that all of these genuinely mental entities are also genuinely physical, from which it follows that some genuinely physical entities are genuinely mental. This should occasion no shock, for it is a consequence of any authentic mental-physical identity thesis. Of course, some call themselves identity theorists and, at the same time, deny the existence of the genuinely mental (in my sense); but the result of this is always some kind of physicalphysical identity thesis rather than a genuine mental-physical identity claim’ (1978: 365). nature. Let me say it again: when I claim that experience (considered just as such—see p. 000) is physical, I’m not saying that it is in any way other than what we ordinarily take it to be (unlike most philosophers when they say that experience is physical). I’m saying that it’s experience exactly as we ordinarily and generally understand it that is wholly physical if materialism is true. This simple point already conflicts directly with many uses of the terms ‘physical’ and ‘materialist’. It’s one of the most unfortunate—stickiest—sticking points of the debate. Materialism is by definition the view that everything in this universe is physical. It accordingly entails that the experiential—the experiential as ordinarily and correctly understood, which we know for certain to exist—is physical. No clear-headed materialist can think that there is a fundamental distinction between the physical on the one hand and the experiential/mental on the other hand, a distinction of such a kind that physical and experiential/mental stand in some sort of opposition.28 So far, perhaps, so good. I also take it to be part of the meaning of ‘physical’ that everything physical has a single fundamental metaphysical nature—a single fundamental metaphysical stuff nature that we denote by the word ‘physical’.29 I’ll call this single fundamental metaphysical stuff nature ‘φ’, so that I can refer to it without using the word ‘physical’. All physical stuff is φ stuff by definition: [h] [x is physical ↔ x is φ]. It follows immediately that materialism is a monist view, a stuff-monist view, according to which there is only one fundamental kind of stuff in reality.30 What it is to be φ is still very largely undetermined. It may be said that [h] is a redundant move. ‘Of course it’s part of the meaning of “physical” that all physical things share the same fundamental-kind nature or stuff-nature. Why introduce a new fundamental-kind term, “φ”, and then say that it’s coextensive with “physical”’? Reply: It seems conceivable that that there are in fact three fundamentally different kinds of stuff or substance in our world— ζ stuff, ξ stuff and χ stuff—that interact smoothly and are all equally part of the subject matter of our science of physics. To rule out this possibility, we need something like [h] in addition to [b] and [c].31 ‘No. In this imagined case, ζ stuff, ξ stuff, and χ stuff are all correctly called ‘physical’ simply because they’re all ‘physics-tractable’ in such a way that they can all be treated in 28 On this point see Strawson 1994: 57–8. A good number of philosophers seem to be trapped in the terminology that allows the opposition. See further below. 29 This allows that physical stuff may be found in other universes: [c] doesn’t state a necessary condition of being physical. 30 Stuff dualism holds that there are two fundamental kinds of stuff (‘Cartesian substance dualism’ is the paradigm case). Stuff monism contrasts with thing monism, the view (held for example by Spinoza) that there is at bottom only one thing (substance, entity) in reality. Schaffer (2010) calls thing monism and stuff monism ‘existence monism’ and ‘substance monism’ respectively. In this paper I take the notion of stuff or substance monism to be viable although it’s not entirely clear what it amounts to: see e.g. Strawson (2003: §15); see also the discussion of ‘fungibility’ in Strawson (2017). 31 In this case, spatiotemporality* isn’t a sufficient condition of same substancehood, nor of physicality (assuming our world is indeed spatiotemporal*). an integrated fashion by a single theory: our physics. That’s just what it is to be physical. So [h] isn’t necessary after all.’ This response fits with the (anti-metaphysical, instrumentalist) way some philosophers think about the meaning of ‘physical’, but it simply overrides the core metaphysical idea that all physical phenomena share a single fundamental stuff nature. The single-naturedness of the stuff of our world is not guaranteed by its physics-tractability. Another seeming possibility, after all, is that two different fundamental kinds of stuff, not only φ stuff but also π stuff, satisfy all the equations of our physics. There may be a π stuff universe distinct from our own. Perhaps there may be a planet made entirely of π stuff, existing inside a π bubble in our otherwise wholly φ universe. If we examine it we’ll take the π planet to be physical stuff, and the cheerful anti-metaphysicalists will say we’re right; but we’ll be wrong. To be physical, then, is not just to be physics-tractable; it’s not just to be tractable for any theory formally identical to physics.32 It’s also to be φ, where φ refers to a certain ultimate intrinsic stuff-nature—the stuff-nature of the stuff that is in fact the only fundamental kind of stuff in our universe. According to PPM, experience is the ultimate intrinsic nature of the stuff of our universe. It may now be said that the notion of fundamental same substancehood has little content unless one can offer some account of how we might possibly decide whether or not smoothly interacting entities are of the same or different fundamental stuffs. This kind of move is sometimes appropriate in philosophy, but not here. Metaphysics is not subject to epistemological constraints of this sort; the notion of same fundamental stuff is sufficiently robust for present purposes (if necessary, we can anchor it in the idea that an omniscient being could tell whether there is one or more substance in play). We can’t assume that physics-tractability is a sufficient condition of fundamental same substancehood. Is the ζ–ξ–χ case really possible? Is it possible given that it requires that there be genuine causal interaction between the three different fundamental kinds of stuff?33 I think it has to be allowed to be possible by anyone who thinks that standard (Cartesian) substance dualism is coherent—even if they think it is false. For when standard substance dualism allows that different fundamental substances may possibly interact causally, it opens up the general possibility that the causal interactions captured by the equations of physics are in fact interactions between different fundamental substances. I’m inclined to take ability to interact causally to be a sufficient condition of same substancehood, directly contrary to the spirit of the ζ–ξ–χ story (see Strawson 2003: 50). This, however, rules out standard Cartesian dualism, and many think that Cartesian dualism is at least a coherent position. 10 Terminology 4: ‘physics’ I haven’t finished with ‘physical’, but I want now to say something about the word ‘physics’, and indeed physics itself, in support of the claim that one has gone badly wrong 32 Physics can be seen as a formal structure which can be given different interpretations or models. I’m assuming that there is such causal interaction and therefore putting aside a ‘Leibnizian’ variant of the case. 33 if one is a materialist and thinks that there is a basic opposition between the physical and the experiential. There is of course an everyday use of ‘physical’ given which the opposition claim comes naturally. But this is precisely the problem: the present claim is that this use is shatteringly unhelpful in philosophy and—at the limit—plain wrong. Certainly we shouldn't use ‘physical’ in philosophy in such a way that Russell, Whitehead, and Eddington and many others are simply contradicting themselves when they say (for example) that from the standpoint of philosophy the distinction between physical and mental is superficial and unreal (Russell 1927a: 402) or that we do not know enough of the intrinsic character of events outside us to say whether it does or does not differ from that of ‘mental’ events (Russell 1927b: 221; see also the quotation on p. 8 above) or that science has nothing to say as to the intrinsic nature of the atom. [From the point of view of physics] the physical atom is, like everything else in physics, a schedule of pointer readings. The schedule is, we agree, attached to some unknown background [the actual physical stuff]. Why not then attach it to something of spiritual nature of which a prominent characteristic is thought [i.e. consciousness]? (Eddington 1928: 259). I agree completely with Maxwell when he says that the physical is, very roughly, the subject matter of physics. By ‘subject matter’ I mean not the theories, laws, principles, etc., of physics, but rather what the theories and laws are about. The physical thus includes tables, stars, human bodies and brains, and whatever the constituents of these may be (1978: 366; my emphasis in bold).34 So what about physics? It’s widely agreed that it can tell us a great deal about structuralrelational aspects of φ, the stuff in our universe (consider the inverse square laws, the mass–energy equivalence equation, the Dirac equation, the Schrödinger equation, etc.). It is at the same time a commonplace that physics is incapable—essentially incapable—of revealing the ultimate structure-transcendent nature of φ, i.e. the nature of the stuff that has to be there given that the structural relations expressed in the equations of physics are actually exemplified by something concretely real. Physics is silent on this aspect of the nature of φ. Why? Because physics is as Hawking says ‘just a set of rules and equations’ (1988: 174). It can’t tell us anything that can’t be expressed in such rules and equations. This is why Eddington says that ‘if you want a concrete definition of matter it is no use looking to physics’ (1928a: 95); physics can’t access ‘its inner un-get-atable nature’ (1928b: 257). ‘Science ignores what anything is in itself’, Whitehead observes: ‘its entities 34 See also Drake (1925: 243), Strong (1930: 327), and Lewis in §6 above. are merely considered in respect to their extrinsic reality, that is to say, in respect to their aspects to other things’ (1925: 153). ‘Physics is mathematical’, says Russell in a passage already quoted, ‘not because we know so much about the physical world, but because we know so little’ (1927b: 125). This isn’t any sort of failure on the part of physics; it’s just not its job. ‘Physical science has reduced nature to activity, and has discovered abstract mathematical formulae which are illustrated in these activities of nature. But the fundamental question remains, How do we add content to the notion of bare activity?’ (Whitehead 1938: 166). It doesn’t follow, in Kantian fashion, that we can’t know anything at all about the nonstructural or structure-transcendent nature of φ—I’ll call this ‘φST’ (‘ST’ for ‘structuretranscendent’). Physics does indeed go beyond purely logico-mathematical structural description in asserting that the universe has specifically spatiotemporal* structure and causal structure, and in taking these to be the fundamental concrete ‘real relations’ or ‘generating relations’ (Newman 1928: 145–6) that the purely logico-mathematical structural descriptions of physics cotton onto. That said, to describe something as causally structured is still to give a highly abstract description of it, a description that is silent on its stuff nature (causation is simply the ‘because something is, something else must be’ relation; Kant 1781–7: B288). The same goes for the description of something as spatiotemporally* structured, to the extent that we remain ignorant of the intrinsic nature of space–time*. I will for this reason include attribution of causal and spatiotemporal* structure under the general heading of structural description, even though it is not purely logico-mathematical structural description. That’s one point. The next point is that if materialism is true, as we’re supposing it is, then we do know something utterly fundamental about φST. This is because we’re directly acquainted with it, at least in certain respects. We’re directly acquainted with φST whenever we’re caught up in the concrete process of having conscious experience, as we so very often are. This is because conscious experience is part of concrete reality, hence a part of physical reality, given materialism; and because, when it comes to conscious experience— and as already remarked—the having is the knowing. As Russell says, using ‘intrinsic’ loosely35 to mean ‘structure-transcendent’: we know nothing about the intrinsic quality of physical events except when these are mental events that we directly experience (1956: 153, my emphasis). When the physical events are mental events that we directly experience, we do know something about their intrinsic structure-transcendent quality. So when Peter Lewis says that quantum mechanics ‘is a theory in which we have no idea what we are talking about, because we have no idea what (if anything) the basic mathematical structures of the theory represent’ (Lewis 2016: 23) we need to make one correction: we do have some idea what we are talking about because sometimes we’re talking about our experiences, whatever else we may or may not be talking about, and we know their intrinsic structure-transcendent 35 It’s loose insofar as it’s natural to think that the structural properties of the physical are also part of its intrinsic nature. nature in certain very fundamental respects. We may then ask whether physical events possess any other, radically different kind of intrinsic structure-transcendent quality. PPM answers No, and (backed up by Occam) challenges dissenters to give good reason to think otherwise. 11 Terminology 5: ‘physical’, ‘materialism’ continued This raises a point about our epistemological limits—a point about the respect in which we will only ever be able to form one kind of descriptively contentful general conception of φST that we can know to cotton on (even if only partially) to the intrinsic nature of φST. Which conception is this? It’s the conception just mentioned, the conception we form of it in having experience and knowing its nature in having it because the having is the knowing. Suppose we let ‘φ*ST’ stand for the structure-transcendent stuff nature of concrete reality without carrying any implication that there is only one fundamental kind of stuff. Suppose we somehow gain access to two different and compelling modes of description of φ*ST, and are able to know that both of them cotton on (even if only partially) to the intrinsic nature of φ*ST. And suppose we continue to have good reason to think that reality as it is in itself forms a causally interconnected whole. In that case, the two modes of description might be so different that we feel we have good reason to suppose that there are two different substances in causal interaction. I take it that that is not our actual case, but many dualists have supposed that it is: that there is, first, the access to the essentially experiential nature of φ*ST that we have simply in having conscious experience, and, secondly, the access to the essentially non-experiential nature of φ*ST that we have not only when we engage in science but also in our everyday experience of moving round in the world. But now we encounter one of the points that supports the panpsychist position: the fact that we do not in fact have the second sort of access. We do not in fact have good reason to think that there is any non-experiential stuff, or that we know its nature in any fundamental non-structural respect. Some may now argue that we’re taking φ*ST to be spatiotemporal stuff whatever else is or is not the case (here I drop the asterisk on ‘spatiotemporal*’ to represent the imagined argument) [e] [x is physical → x is a spatiotemporal entity] and that anything spatiotemporal must be spatially extended [i] [x is a spatiotemporal entity → x is spatially extended] and that anything spatially extended must have some sort of non-experiential stuff nature [j] [x is spatially extended → x has non-experiential stuff being], and therefore that [k] [x is physical → x has non-experiential stuff being]. And this may seem to settle the case against PPM. But [k] isn’t warranted. First, we don’t know that we know the nature of space–time (see p. 13). I think we can safely say that we know we don’t fully know the nature of space–time. Secondly, and more importantly, it’s not at all obvious that space-occupation requires non-experiential stuff being, even if it seems so at first.36 Some philosophers and physicists seem to think that a concretely real thing can exist in a spatiotemporal universe and have no spatial extension at all. I think that’s plainly incoherent [see 000], so I’m prepared to agree that [l] [x is physical → x is spatially extended] —always assuming that concrete reality is indeed fundamentally spatiotemporal. I’m also prepared to put aside the view that we may be (surely are) deeply ignorant of the intrinsic nature of space, although it already supplies grounds for rejecting the objection to PPM in the last paragraph, and to take it that we really do have a reasonably good if partial positive intuitive (more than merely structural) grasp of its nature. For, even then, when I go on to think of the (Heisenbergian) energy that wholly constitutes everything that we think of as spatially extended (and even, perhaps, space–time itself), and then go on to raise the question of the intrinsic stuff-nature of this energy, and then go on to consider the current hypothesis that it’s wholly a matter of experientiality—the active, live occurrent phenomenon that we know experience to be—I can see no good reason to think that something consisting of wholly experiential stuff cannot be spatial in just the same way as the way in which something thought of as non-experiential is supposed to be; so I reject [j], which was used in conjunction with [e] and [i] to argue for [k], even as I accept [l]. This leads to an important related point. Wholly experiential stuff can certainly be said to have numerical and structural properties, and numerical and structural properties, considered specifically as such, are indeed correctly called non-experiential properties. It does not, however, follow from this that there is any non-experiential stuff; it doesn’t follow that there are any non-experiential stuff-properties. So one can’t refute PPM simply by showing that one can correctly ascribe properties to concrete reality that are correctly or naturally said to be non-experiential properties. Failure to appreciate this point is likely to be another potent source of misunderstanding. ‘Non-experiential’ is not the name of a positive type of stuff being; to say that a thing has non-experiential properties is not ipso facto to say that it has any non-experiential stuff being.37 The property of having temporal duration is in itself an entirely non‐experiential property, and it is, again, a property which may be exemplified without there being any non‐experiential stuff. More generally, one can say this: whatever the dimensionality of the concrete real, a 36 See chapter 000 [Strawson (2017: 382–3) for an argument that it does not; it’s a tricky issue. It’s worth noting that a good number of early modern philosophers took immaterial stuff to be spatially extended. 37 I try to clarify this issue in Strawson 2016: 87–90, where I introduce ‘hylal’ as a positive term for a specific type of non-experiential stuff being distinct from experiential being. panpsychist may take it that its nature is such that it fits smoothly with the nature of the concrete real conceived of as nothing but experientiality in exactly the same way as the way in which the dimensionality of the concrete real understood as spatial in the conventional way is seen to fit smoothly with the nature of the concrete real understood as good old fashioned non-experientially propertied physical stuff. ‘But you must retain the idea of dimensional position, even when you take the dimensionality of the concrete real to fit smoothly with the view of the concrete real as wholly experiential, because the idea of position and difference of position is essentially built into the idea of dimensionality. And the property of having some dimensional position is essentially non-experiential.’ True; but the reply is the same as before. This raises no difficulty for the idea that the stuff nature of the concrete real is experientiality. It may be added that non-pure materialist panpsychism (or ‘psychism’—see pp. 000) remains an option (if it is indeed coherent as a form of monism), even if one continues to think that spatiotemporality entails nonexperiential stuff. 12 Terminology 6: ‘physical’, ‘materialism’ continued So: to be a materialist is simply to hold [c] that all the stuff in this universe, including of course [g] all experientiality, is wholly physical. To be a serious or realistic materialist is to be (with Russell and almost all if not all materialists until some time in the twentieth century) a real, five-year-old-Lucy realist about experience. It’s also to hold (again with Russell) that in having experience we know something about the intrinsic nature of the physical. What is it to be physical? It is (at least) to be [a] concrete, [b] what physics talks about, in its own strictly limited way, [d] physics-tractable, [e] spatiotemporal(*) and hence [l] spatially(*) extended, and [h] of a single kind of fundamental stuff φ whose singlekindhood must be allowed to transcend physics-tractability by anyone who allows that the story of ζ stuff, ξ stuff and χ stuff is coherent. On this view, leptons and quarks, fermions or bosons, matter and anti-matter, charged and chargeless particles (these are familiar classificatory distinctions made within the realm of the physical) are all of the same fundamental kind of stuff, although they are importantly different types of things. They are as one might say all made of the same fundamental kind of stuff. Don’t ask me how we might identify and distinguish fundamental kinds of stuff—what criteria we might use. I don’t have access to Concretics, God’s great textbook about concrete reality, in which all possible types of concrete stuff are specified. I’m simply expounding a way of understanding ‘physical’ according to which ‘physical’ carries an implication of sameness of fundamental nature that goes beyond being treatable by a single theory, mathematical physics. [h] is (among other things) a dramatization of the point that ‘physical’ is a natural-kind term of a special kind.38 38 It’s special, as a natural-kind term, because we do know something for sure about the intrinsic nature of the physical if physicalism is true, because (once again) we know that our experience is concretely real, and hence physical if physicalism is true, and there is a fundamental respect in which we know its nature in having it. (This claim that ‘we know its nature’ is likely to be misunderstood by anyone who hasn't taken in Some may think that the above characterization of ‘physical’ is still radically incomplete, because it’s part of the core or fundamental meaning of ‘physical’ that [m] [x is physical → x is at least partly constituted of non-experiential stuff]. Many endorse the stronger view that [n] [x is physical → x is wholly constituted of non-experiential stuff]. Russell and many others disagree, as I do. Nothing in physics provides compelling reason to endorse [m] or [n]. They may certainly be allowed to be part of the meaning of ‘physical’ (or ‘material’) in everyday use, but no one who uses ‘physical’ when engaged in metaphysical speculation about the fundamental nature of things—using it to mean the stuff of which the world is in fact constituted, or the stuff that physics is in fact concerned with and (so we believe) says many true things about—should accept this feature of the ordinary meaning of ‘physical’ as a constraint on the theoretical employment of the term. It’s not just that physics radically undermined the everyday conception of the nature of matter long ago. The deeper point is that physics itself rules against this constraint by its very nature. Many physicists have been completely clear about this, including H. A. Lorentz, Max Planck, Ernst Schrödinger, Louis de Broglie, David Bohm (see quotations on pp. 000). This is the silence of physics. It used to be well known: ‘the materialist, holding that the world is matter, is not wedded to any one doctrine of the nature of matter’ (Williams 1944: 425). ‘Physical’ is not a term that carries or contains any determinate positive descriptive non-structural characterization of a kind of stuff. Some philosophers may now say that the characterization of the word ‘physical’ (or ‘material’) proposed here is bad because it’s incompatible with the terminology of the traditional debate about the ‘mind-body problem’, which has matter (the physical) firmly and comfortably on one side, and mind and conscious experience (the mental, the experiential), firmly and comfortably opposed to matter, on the other. I think this is the opposite of the truth. This incompatibility is perhaps the key virtue of the current characterization of ‘physical’. The traditional debate is a dead end, full of seductive patterns of confusion, many of which revolve principally around the use of the word ‘physical’.39 We know experience is real, so we know that experience is physical if materialism is true, and the fundamental metaphysical question, given that we know that there is experiential physical stuff, is whether there is any respectable reason to posit any non-experiential physical stuff. I think that the best (and Occamical) answer may be No. And now Quine and Nietzsche turn up at my side. Nietzsche points out, correctly, that the view that ‘substance is experienceless is only a hypothesis! Not based on experience!’ (1883–4: KSA 10, 24[10]). Quine (using ‘physical’ in the standard sense that implies having non-experiential being) observes that physical objects are ‘posits comparable, note 20 above and the paragraph to which it is attached.) 39 Most of the others flow from an inadequate conception of properties—of the relation between properties and what they are properties of. See 000.. epistemologically, to the gods of Homer’ (1951: 44). 13 Terminology 7: ‘radical emergence’ I want now to say briefly what I mean by ‘radical emergence’ (also called ‘strong emergence’, see e.g. Wilson 2015) and then conclude. In a case of radical emergence, as I understand it, some concrete stuff develops into or produces or comes to constitute some concrete stuff that belongs, intuitively, and presumably also in fact, to a wholly, radically different order of being. In the present case the first stuff is by hypothesis non-experiential, so I’ll call it NE. The second stuff is experientiality, experiential stuff, so I’ll call it E. E being is held to emerge—wholly naturally—from NE being that is quite radically different from it: either constitutively (E being emerges from NE being as a result of some NE being’s coming to constitute some E being) or causally (some E being emerges from some NE being inasmuch as some NE being causes some E being to come into existence). One way to illustrate the force of ‘radical’ is to observe that one can transform or develop any form of matter into any other (steel into marshmallow, water into diamond), given sufficient force. No such transformation will be a case of radical emergence, because all matter is made of the same stuff (leptons and quarks, on one account). In fact the same goes for transforming matter into antimatter. This may sound as if it must be a case of radical emergence, but all this shows is that the terms ‘matter’ and ‘antimatter’ are potentially misleading. The only difference between an electron and an anti-matter electron (a positron) is that their charges are reversed. These are not cases of radical emergence. The transformation of wholly and utterly NE stuff into E stuff—experiencing, experientiality—would, by contrast, be a case of radical emergence; so I claim. I have no argument for this very widely held view, nor anything to add to the kinds of intuitive considerations I’ve given before (Strawson 2006a and 2006b). I’m not claiming that radical emergence is provably impossible. I don’t think it is, although I think that the postulation of radical emergence must always be a huge black mark against a theory. 14 Radical emergence The principal objection to taking it that E exists in our universe by virtue of radical emergence from wholly and utterly NE can be put as follows. I’ll use ‘E’ (italic capital) to refer to all theories that suppose that the fundamental stuff is wholly experiential, ‘NE’ to refer to all theories that suppose that the fundamental stuff is wholly non-experiential, and ‘RE’ to refer to the view that radical emergence exists. [1] We know for certain that E exists (biological E, at the very least). [2] We don’t know for certain that any NE exists. So right from the start, [3] the burden of proof is on those who believe that NE exists. [4] There is, to begin, a burden on them to prove that it exists at all. This burden is very heavy; in fact it can’t be lifted. It’s a very old and familiar point that [5] it can’t be proved that NE exists. The point [5] that it’s impossible to prove that there is any NE being is weighty. But let us put it aside. Even when we put it aside it remains true that [6] there is a burden on those who believe that NE exists to show that there is at least good reason to posit NE. It looks, however, as if [7] E and NE+RE are empirically equivalent (theories are empirically equivalent if no empirical test can decide between them). This is because it seems that [8] our best and most fundamental science of the nature of reality—physics—can’t decide between them. Why not? Because of the silence of physics on the question of the intrinsic structure-transcendent nature of reality. The reference of the terms that refer to the structure-transcendent reality can as Quine says ‘be wildly reinterpreted without violence to evidence’ (1992: 9). If this is right, [9] it won’t be possible to find good reason to posit NE in addition to E (E which we know for certain to exist). At this point I think that there’s only one thing left for the advocates of NE to do. They need to try to show that [10] even if NE+RE and E are empirically equivalent, still NE+RE is theoretically superior to E. Their first and very large difficulty is immediate: there appears to be no reason to posit radical emergence anywhere else in science. It is to that extent sorely ad hoc to posit it just and only in the case of experience. It’s directly contrary to the dictates of sound methodological naturalism. Suppose the advocates of NE press on, in spite of this, and turn to perceived problems for E in the hope that they can show at least one of them to be insuperable. They are likely to turn to the most popular perceived problem for E—the problem of how we account for the existence of biological experience like our own given the postulation of non-biological experience—and argue more or less as follows. Suppose first that [11] we assume an irreducibly plural ontological setup in concrete reality (i.e. reject thing monism). Suppose for example that we take the language of particle physics more or less literally, if only for purposes of argument. In this case, say the advocates of NE, [12] E faces the ‘combination problem’.40 Experience can’t exist without an experiencer of some sort, and it appears to follow that (non-biological) particle-like microexperiences entail the existence of (non-biological) particle-like microexperiencers. But how can non-biological microsubjects combine to constitute biological macrosubjects like ourselves? The combination problem is so acute, they say, that [13] it’s more plausible to suppose that biological E arises from or consists in the activity of a multiplicity of NE microelements than a multiplicity of non-biological E microelements. Suppose alternatively that [14] we think of the universe in the way a considerable number of present-day cosmologists and philosophers think best, i.e. as ultimately a single thing structured or indeed constituted by a number of fields, or perhaps one complex field. Even then (say the advocates of NE) [15] it’s more plausible to suppose that biological E arises from or consists in some sort of activity-complexity in fields that have a fundamentally NE intrinsic nature than to think that it arises from or consists in some sort of activity-complexity in fields that have a fundamentally E intrinsic nature. 40 See e.g. Lucretius (c50 BCE), Clarke (1707–18), Kant (1781–7), James (1890: ch. 6), Goff (2006), Chalmers (2015); I’m going to take general familiarity with the combination problem for granted, and stick to the ‘subject combination problem’. I can see no force in [15]. There does seem to be some initial force to [12], given [11], but, first, even if it’s very difficult, when we think in a simple particle-physics way, to conceive of how biological E arises from or consists in the activity of a multiplicity of nonbiological E elements, and hardly less difficult, when we think in the field-theoretic way, to conceive of how biological E arises from or consists in some sort of activity-complexity in a non-biological E field, it’s most unclear that it’s easier to imagine that biological E arises from or consists in the activity of a multiplicity of NE elements, or some sort of activitycomplexity in an otherwise fundamentally NE field. Many have said that there is a special and overwhelming difficulty in the idea that a multitude of subjects can combine into a larger single subject, including, famously, William James in The Principles of Psychology (1890: 160). But this leads directly to a second reply to those who wish to argue that E faces such acute problems that it’s reasonable to suppose that NE+RE is theoretically superior to E. The point is simple, and has wide implications when to comes to the general discussion of idealist theories, panpsychist or not. Almost all those who have argued that the combination problem is insuperable for panpsychism have used a priori argument in support of their case. This is why they’ve supposed that the arguments are decisive. It is, however, foolish to suppose that a priori argument can have any decisive role to play in this matter. A hundred years ago someone might have argued, with supreme confidence, and on purely a priori grounds, that wave-particle duality or quantum entanglement or quantum superposition was provably impossible. That would have been a mistake. We have daily proof from physics that there are fundamental things about the nature of concrete reality, and in particular the structural-relational-combinatorial nature of concrete reality, that we don’t understand and have no prospect of understanding. William James anticipates this general point beautifully, I believe, when in A Pluralistic Universe (1909), in a chapter called ‘The Compounding of Consciousness’, he simply abandons his earlier a-priori-argument based endorsement of the view that the combination problem is insuperable. He understands our ignorance. Kant also anticipates this point— shows a suitable grasp of our ignorance—when he considers one of the standard ‘rationalist’ or immaterialist objections to the materialists: if someone rejects materialism (or equally micropsychism, the idea that there are many small non-biological E elements) and argues for a simple non-material soul merely on the ground that the unity of apperception in thought does not allow of its being explained [as arising] out of the composite, instead of admitting, as he ought to do that he is [quite generally] unable to explain the possibility of a thinking nature (einer denkender Natur, a mind), why should not the materialist [or equally the micropsychist], though he can as little appeal to experience in support of his possibilities, be justified in being equally daring, and in using his principle to establish the opposite conclusion? (Kant 1787, B417-18, my emphasis).41 41 i.e. that the unity of apperception does arise from the composite. Kant undermines the view that we can know that the mind or soul or thinking subject is a single substance in his discussion of the Second Paralogism. He grants—stresses—the sense in which the thinking subject is something that is necessarily single in the activity of thought or experience, and points out that we cannot infer its ultimate metaphysical simplicity from this fact. We just don’t know enough to reach conclusions of the ‘rationalist’ sort. James and Kant aside, I think that the general doubt about the use of a priori argument in this domain (a doubt itself strongly supported by physics) is enough to establish that we have no good reason to pay much attention to standard formulations of the combination problem.42 We have to remember and respect our ignorance, however much it galls us. We have to remember Orgel’s Second Rule: ‘Evolution is cleverer than you are’. If it’s adaptive for a portion of matter that moves around under its own steam as a single unit to have an environment-representing experiential perspective that corresponds to that singleness, evolution will make it happen, even if (and this is far from obvious, given the field-theoretic conception of reality) it has to conjure that perspective out of many experiential perspectives. We have to remember the silence of physics, and the fact that even when we limit ourselves to the limited sorts of things that physics can tell us about, nature appears to be more puzzling than we are likely to be able to understand. After acknowledging all the known unknowns, we have to remember the unknown unknowns, not to mention the unknowable unknowns, not to mention the knowably unknowable unknowns.43 15 Conclusion This paper has gone on long enough.44 I want to conclude with an apparent difficulty. I’m attracted to the thing-monist view according to which the universe is a single thing in some non-trivial sense, and is indeed space–time* (i.e. not ultimately ontologically distinct from what we think of as its dimensionality). On this view space–time* itself is a substantial something, a stuffy something, a plenum, a weave of fields, or rather perhaps a single complex field—which is in fact an experientiality field. This picture raises a large question. For if the universe is space–time*, and if space– time* is stuff, and if it is experiential stuff, and if it is also, in a fundamental sense, a unity, and if the existence of an experience entails an experiencer, in some fundamental and ineliminable sense, as I believe it does, then—so it seems—we must not only suppose that the universe is itself a subject, but must also (unless considerations about the nature of time show this to be a mistake) suppose that it is experiencing all the disparate and often mutually incompatible thoughts and feelings of all sentient beings. I’m not sure what to say about this. Certainly there are ways of conceiving of what we are, and of why it is that we experience ourselves as radically bounded subjects, that don’t clash irreconcilably with the seemingly extraordinary idea of a cosmic subject. On the terms of §5, we’re local peaks in the great experiential weave. We’re not in fact radically isolated experiential units, but we are sweetly tuned by evolution to experience ourselves as such; where to say this is not to say that our sense of mental singleness is merely an illusion. 42 I like to think (hope) that this general line of thought applies to all the problems listed in Chalmers (2015). See further Stoljar 2006a, 2006b. 44 I offer a direct four-stage argument that PPM is the most plausible theory of concrete reality in chapter 000 [=Panpsychism: “a revised materialism” pp. 000–000)]. 43 One possible solution is to give up thing monism. Some think that thing monism is the best or only way to avoid the combination problem (see e.g. Goff 2017); but I can’t feel worried by the combination problem, for reasons given in the previous section. Another possibility, perhaps, is that the single experientiality field (weave of fields) is a unity in some way that doesn’t require the universe to be itself a single subject of experience. Goff engagingly suggests that the universe is indeed conscious, but that ‘the consciousness of the universe is simply a mess. It may be hard for us to imagine a single mental state involving such wildly conflicting contents [as the contents of all our different respective streams of consciousness], but I see no reason to think that such a thing is impossible’ (2017: 243). As a passionate materialist naturalist atheist, I think the thing to do is to relax. Die Welt ist tief—as Nietzsche observed (1883–92: 264). The general case for favouring panpsychism over other theories of the fundamental nature of reality is close to being overwhelming, independently of issues like this one. My current sense is that a single experiential field doesn’t require a single subject in any alarming sense. And if panpsychist thing monism did require the existence of such a subject, it wouldn't, I think, be any sort of intentional agent. The universe is a vast, magnificent, and from some perspectives terrifying unfolding of being, but I don’t think anyone or anything can do anything about how it goes.45 45 My thanks to Cory Juhl, Peter Lewis, Bill Seager, Jim Weatherall, and members of the Shanghai workshop on idealism held in June 2017. References Berkeley, G. (1710/1998) A Treatise Concerning the Principles of Human Knowledge, J. Dancy (ed.), Oxford: Oxford University Press. Cavendish, M. (1664/1994) ‘Letter 30’ of Philosophical letters: Or, modest reflections upon some opinions in natural philosophy in M. Atherton (ed.) Women Philosophers of the Early Modern Period, Indianapolis: Hackett, pp. 24-29. Chalmers, D. (2015) ‘Panpsychism and Panprotopsychism’ in T. Alter and Y. Nagasawa (eds.) Consciousness in the Physical World: Perspectives on Russellian Monism, New York: Oxford University Press. Clarke, S. and Collins, A. (1707–1718/2011) The Clarke-Collins Correspondence of 1707-18, W. Uzgalis (ed.), Peterborough, ON: Broadview Press. Drake, D. (1925) Mind and Its Place in Nature, New York: Macmillan. Eddington, A. (1928a) Review of The Analysis of Matter, Journal of Philosophical Studies 3/9, pp. 93–95. Eddington, A. (1928b) The Nature of the Physical World, New York: Macmillan. Goff, P. (2006) ‘Experiences don’t Sum’ in A. Freeman (ed.) Consciousness and its Place in Nature, Thorverton: Imprint Academic, pp. 53-61. Goff, P. (2017) Consciousness and Fundamental Reality, Oxford: Oxford University Press. Griffin, D. (1998) Unsnarling the World-Knot: Consciousness, Freedom, and the Mind-Body Problem, Berkeley, CA: University of California Press. Hartshorne, C. (1936) ‘The Compound Individual’ in O. Lee (ed.) Essays for Alfred North Whitehead, London: Longmans, Green, pp. 193–220. Hartshorne, C. (1942) ‘Organic and Inorganic Wholes’. Philosophy and Phenomenological Research 3/2: 127-36. Hawking, S. (1988) A Brief History of Time, New York: Bantam Books. Heil, J. (2012) The Universe As We Find It, Oxford: Oxford University Press. Heil, J. & Martin, C. B. (1998) ‘Rules and powers’. Philosophical Perspectives 12: 283-312. Heisenberg, W. (1958) Physics and Philosophy. New York: Harper and Brothers. James, W. (1890/1950) The Principles of Psychology. New York: Dover. James, W. (1909/1996) A Pluralistic Universe. Lincoln, Nebraska: University of Nebraska Press. Kant, I. (1766/1992) Dreams of a Spirit-Seer in D. Walford (ed.) Theoretical Philosophy 1755-1770, ed. David Walford, New York: Cambridge University Press, pp. 301-60. Kant, I. (1781-7/1933) Critique of Pure Reason. N. Kemp Smith (trans.) London: Macmillan. Laudan, L. (1981) ‘A Confutation of Convergent Realism’. Philosophy of Science 48/1: 19-49. Lewis, D. (1983/1999) ‘New Work for a Theory of Universals’ in Papers in Metaphysics and Epistemology, Cambridge: Cambridge University Press, pp. 8-55. Lewis, D. (1986) On the Plurality of Worlds, Oxford: Blackwell. Lewis, D. (1994) ‘Reduction of Mind’ in S. Guttenplan (ed.) A Companion to the Philosophy of Mind, Oxford: Blackwell. Lewis, P. (2016) Quantum Ontology: A Guide to the Metaphysics of Quantum Mechanics, Oxford: Oxford University Press. Nietzsche, F. (1882–4) Nachgelassene Fragmente 1882–1884: Sämtliche Werke 10, Berlin: de Gruyter. Locke, J. (1689–1700/1975) An Essay concerning Human Understanding, P. Nidditch (ed.) Oxford: Clarendon Press. Lovejoy, A. O. (1913) ‘Realism versus Epistemological Monism’. Journal of Philosophy, Psychology and Scientific Methods 10/21: 561-72. Lucretius (c50 BCE/2007) The Nature of Things. A. Stallings (trans.) London: Penguin. Maxwell, G. (1978) ‘Rigid Designators and Mind-Brain Identity’ in C. Wade Savage (ed.) Perception and Cognition: Issues in the Foundations of Psychology, Minneapolis: University of Minnesota Press, pp. 365-403. McHenry, L. and Shields, G. (2016) ‘Analytical Critiques of Whitehead’s Metaphysics’. Journal of the American Philosophical Association CJO 2016 doi:10.1017/apa.2016.21. Montague, M. (2016) The Given, Oxford: Oxford University Press. Mørch, H. H. (2014) Panpsychism and Causation: A New Argument and a Solution to the Combination Problem, University of Oslo, PhD dissertation. URL = https://philpapers.org/archive/HASPAC-2.pdf. Mørch, Hedda Hassel (2017) The evolutionary argument for phenomenal powers. Philosophical Perspectives 31 (1):293316. Nagel, T. (1979) ‘Panpsychism’ in Mortal Questions, New York: Cambridge University Press, pp. 181-95. Nagel, T. (2012) Mind and Cosmos: Why the Materialist Neo-Darwinian Conception of Nature is Almost Certainly False, Oxford: Oxford University Press. Newman, M. (1928) ‘Mr. Russell's “Causal Theory of Perception.”’ Mind 37: 137–48. Nietzsche, F. (1883–1892/2006) Thus Spoke Zarathustra: A Book for All and None. A. del Caro (trans.) Cambridge: Cambridge University Press. Pautz, A. (2009) ‘A simple view of consciousness’ in R. Koons & G. Bealer (eds.) The Waning of Materialism: New Essays, Oxford: Oxford University Press, pp. 25–66. Quine, W. V. (1981) Theories and Things, Cambridge, MA: Harvard University Press. Quine, W. V. (1992) ‘Structure and Nature.’ The Journal of Philosophy 89/1: 5–9; Russell, B. (1912/1959) The Problems of Philosophy, Oxford: Oxford University Press. Russell, B. (1927a/1992) The Analysis of Matter, London: Routledge. Russell, B. (1927b) An Outline of Philosophy, London Allen & Unwin. Russell, B. (1948/1992) Human Knowledge: Its Scope And Limits, London: Routledge. Russell, B. (1956/1995) ‘Mind and Matter’ in Portraits from Memory, Nottingham: Spokesman, pp. 135-53. Russell, B. (1959) My Philosophical Development, New York: Simon and Schuster. Seager, W. (1995) ‘Consciousness, Information and Panpsychism’. Journal of Consciousness Studies 2/3: 272-88. Seager, W. (2010) ‘Panpsychism, Aggregation and Combinatorial Infusion’ in Mind & Matter 8/2: 167–84. Seager, W. (2016) ‘Panpsychist Infusion’ in G. Brüntrup and L. Jaskolla (eds.) Panpsychism: Contemporary Perspectives, New York: Oxford University Press, pp. 229-48. Sellars, R. W. (1927) ‘Why Naturalism and Not Materialism?’ Philosophical Review 36: 216-225. Shepherd, M. (1824) An Essay upon the Relation of Cause and Effect, &c. London: Hookham. Siegel, S. (2017) The Rationality of Perception, Oxford: Oxford University Press. Skrbina, D. (2005) Panpsychism in the West, Cambridge, MA: MIT Press. Smart, J. J. C. (1963) ‘Materialism’, Journal of Philosophy, 60: 651–662. Sprigge, T. L. S. (1983) The Vindication of Absolute Idealism, Edinburgh: Edinburgh University Press. Spinoza, B. de (1677/1985) Ethics in E. Curley (ed. and trans.) The Collected Works of Spinoza, Princeton: Princeton University Press. Stoljar, D. (2006a) Ignorance and Imagination: on the epistemic origin of the problem of consciousness, Oxford: Oxford University Press. Stoljar, D. (2006b) ‘Comments on Galen Strawson’ in A. Freeman (ed.) Consciousness and its Place in Nature, Thorverton: Imprint Academic, pp. 170–76. Strawson, G (1994) Mental Reality, Cambridge, MA: MIT Press. Strawson, G. (2003/2008) ‘Real materialism’ in Real Materialism and Other Essays, Oxford: Oxford University Press, pp. 19-52. Strawson, G. (2006a) ‘Realistic monism: why physicalism entails panpsychism’ in A. Freeman (ed.) Consciousness and its place in nature, Thorverton: Imprint Academic, pp. 3-31. Strawson, G. (2006b) ‘Reply to commentators, with a celebration of Descartes’ in A. Freeman (ed.) Consciousness and its place in nature, Thorverton: Imprint Academic, pp. 184-280. Strawson, G. (2008) ‘The Identity of the Categorical and the Dispositional.’ Analysis 68: 271-82. Strawson, G. (2016) ‘Mind and being: the primacy of panpsychism’ in G. Brüntrup and L. Jaskolla (eds.) Panpsychism: Philosophical Essays, New York: Oxford University Press, pp. 75-112. Strawson, G. (2017).‘Physicalist panpsychism’ in S. Schneider and M. Velmans (eds.) The Blackwell Companion to Consciousness (2nd ed.), New York: Wiley-Blackwell, pp. 374-90. Strawson, G. (2018) ‘The silliest claim’ in Things That Bother Me, New York: New York Review Books. Strawson, G. (2019) ‘A hundred years of consciousness: a long training in absurdity’. Estudios de Filosofía 59: 9–45. Strong, C. A. (1918) The Origin of Consciousness: an Attempt to Conceive the Mind as a Product of Evolution. London: Macmillan. Strong, C. A. (1930) ‘Nature and Mind’ in G. P. Adams and W. P. Montague (eds.) Contemporary American Philosophy: Personal statements (vol. 2), London: George Allen and Unwin, pp. 313-32. Stubenberg, L. (2016) ‘Neutral Monism’, The Stanford Encyclopedia of Philosophy (Winter 2016 Edition), Edward N. Zalta (ed.), URL = <https://plato.stanford.edu/archives/win2016/entries/neutral-monism/>. Tolman, E. C. (1932) Purposive Behaviour in Animals and Men. New York: Century. Turausky, K. (MS) ‘Picturing Panpsychism: New Approaches to the Combination Problem(s)’. Wallace, D (2013) ‘A Prolegomenon to the Ontology of the Everett Interpretation’ in A. Ney and D. Albert (eds.) The Wave Function: Essays on the Metaphysics of Quantum Mechanics, Oxford University Press, pp. 203-22. Weinberg, S. (1997) ‘Before the Big Bang’ in The New York Review of Books 44/10 (June 12). Whitehead, A. (1925/1967) Science and the Modern World. New York: The Free Press. Whitehead, A. (1938/1969) Modes of Thought. New York: The Free Press. Whitehead, A. (1927–8/1978) Process and Reality: An Essay in Cosmology corrected edition, ed. D. Griffin and D. Sherburne. New York: Free Press. Williams, D. C. (1944) ‘Naturalism and the Nature of Things.’ The Philosophical Review 43: 417-443. Wilson, J. (2015) ‘Metaphysical Emergence: Weak and Strong’ in T. Bigaj and C. Wüthrich (eds.) Metaphysics in Contemporary Physics, Amsterdam/New York: Rodopi/Brill. Wishon, D. (2015) ‘Russell on Russellian monism’ in T. Alter and Y. Nagasawa (eds.) Consciousness in the Physical World: Perspectives on Russellian monism, Oxford: Oxford University Press), pp. 91–118.