Dualism – the view that mind or spirit is different from body and brain – is widely derided in much modern thought. But actually it is just one of a number of widely held philosophical views about what is really real, and about what human persons are. In this chapter I outline five of them, all held by reputable philosophers: phenomenalism (the view that all human knowledge is built up from, and is basically limited to, sense-experience); naive realism (the view that the world exists very much as we see it, even when we are not observing it); materialism (the view that only material objects, perhaps publicly observable objects in space-time, are ultimately real); dualism; and epiphenomenalism (the view that minds exist and are different from matter, but that they are wholly dependent upon brains, and play no causal role in anything that happens, as the material brain does all the work). Materialism, though currently very popular, is just one of these views, and I argue that on purely philosophical grounds materialism is less plausible than dualism.
What is really real? Are there sense-data, as Ayer supposed? Is there an immaterial thinker, as Descartes supposed? Or are (almost) all statements about minds analysable into dispositional, “if-then” statements about the behaviour of publicly observable bodies, as Ryle supposed? It seems as if what these philosophers are doing is to start from a basic set of axioms, trace out what can be inferred or deduced from them, and then see how these consequences fit with their experience of reality. They are each able to see the weaknesses in their opponents’ theories, and propose accounts that try to remedy them. Ayer accepts Descartes’ claim that mental occurrences like thoughts and images could exist without physical bodies, but rejects the claim that there is an immaterial subject who has such thoughts and images. Ryle accepts Ayer’s claim that all factual statements must be verifiable in principle, but rejects the claim that such verification consists in having private sense-experiences which no one else could ever check. I am accepting Ryle’s claim that many (not all) statements about mental properties are dispositional statements about what a human animal is capable of doing or is liable to do in various circumstances. But I am querying his claim that there are no private and non-spatially locatable mental occurrences.
Does this mean there is a ghost in the machine after all? Ghosts are usually visual appearances of people, but they lack solidity and they tend to moan and wail rather a lot. I don’t suppose anyone thinks that inside their head there is a wailing gaseous hallucination which pulls the levers that make the brain work. That is plainly ridiculous, and it is meant to be. The metaphor of a ghost in the machine has worked well as a rhetorical device to make people think that we all know the brain (the machine) is real, whereas talk of a mind other than the brain or of mental events in addition to brain-events is talk about something peculiar, not quite real, and probably illusory (a ghost).
It seems to me that the situation is quite the reverse. Talk of mental events is the most real thing we humans know. We know we have sense-experiences, bodily sensations, thoughts, feelings, and images. We know we experience things in ways that are unique to us and never wholly communicable to other people. We know that all our knowledge of the world has to begin with such experiences. Mental events are real, and to deny them would deprive us of all knowledge. They are not ghosts or hallucinations at all.
But do we know that brains are real? Well, yes, because we can see and feel them, at least if we are surgeons or pathologists. But may the brains we observe only be appearances to us of a reality which is rather different from what we see? This is another standard problem for first-year philosophers: what would brains look like if we were not looking at them?
We can never find out by observation, because every time we look at something we only see the way it looks to us. It is no use trying to cheat by closing our eyes and then opening them very quickly, as if to take the world by surprise. However quickly and surprisingly we manage to take a peek, we still only see what things look like to us. We can never manage to take them unawares, and find out what they look like when no one is looking at them.
This is very frustrating. We are tempted to say, “Well, obviously, they go on being the same whether we are looking at them or not.” But there are good reasons for thinking this is not true. One of the most important features of objects in our experience is colour. When we admire a beautiful view, we usually admire the colours objects have. But physicists tell us that colour is a product of the brain. External objects emit electromagnetic waves. Some of these impinge on the cones in human eyes, and cause electrochemical impulses that land up in the visual cortex. Only after that long causal journey do colours appear to us. The original wavelengths have no colour. They cause sensations of colour when they affect human sense-organs and the human brain. Colours are precisely some of those private mental states that Ryle wanted to get rid of. Different individuals may see colours in rather different ways. Colour-blind people certainly do. And some animals do not seem to see colours at all (they have no cones in their eyes). What we see depends on our cognitive apparatus.
But where are the colours themselves? They are not literally in the brain, as physical objects. The brain does not change colour when we see coloured objects. They are not on the objects we see, which have no colour. Colours are, as John Locke said, following Galileo, secondary qualities. They do not belong to external objects. They are contents of the mind, when stimulated by the brain, which in turn has been stimulated by wavelengths of light. Colours are caused by physical events, but they are not themselves physical events. They are how consciousness perceives physical events. There is a causal basis of conscious events, but it does not exist as we see it.
Brains are rather boring, where colour is concerned. They are usually greyish. But are brains grey when we are not looking at them? Apparently not; they then have no colour at all. In fact, we could go much further than this and say that brains are not the solid porridge-looking objects they appear to be. Any physicist will say that brains are mostly empty space, in which molecules, atoms, electrons, quarks, and other strange particles buzz about in complicated ways.
It seems as though physical objects, when not being observed, have no colours, and no sounds, smells or tastes either. Sounds, like colours, are not physical events. Neither are smells, tastes or sensations. Things do not smell like, taste like or feel like anything, when nobody is smelling, tasting or feeling them. The physical world, it seems, is totally vacuous. No colours, sounds, smells, tastes or sensations. What on earth is left?
Wet philosophers
For Locke and Galileo, what is left is a world of “primary qualities” – qualities which, they thought (wrongly, as modern physics shows) physical objects cannot fail to have, but which are quite distinct from the “secondary qualities” that we see, hear, and feel, but which do not belong to the physical world. The world of primary qualities, the “real world”, is basically a world of colourless, intangible, inaudible particles located in space, moving around and continually bumping into one another (though of course not realizing that they are doing so).
Science tells us that all objects are made of atoms and other very small particles, and that atoms have no colour, smell or taste. They just have properties like mass, charge, position, and momentum. So they are not exactly how they look to a human being.
When oxygen and hydrogen atoms are put together in a particular way, they feel wet to human observers – they form molecules of water. But if there were no observers, they would not be wet. There would not be any wetness. There would only be what John Stuart Mill called “a permanent possibility” of wetness, which would only become actually wet when somebody went for a swim.
Thus there is no point in asking Mill whether the sea is warm enough for swimming. He would have to reply, “Not yet, but it might be if you jump in.” Anyone who thinks that we see things as they actually are, however, would say that the sea is wet and warm, even if there is nobody about. But there is a problem. How do we know? There is absolutely no way of checking, without jumping in – and then of course you have not proved that it was wet and warm before you jumped in. This is why, on the philosophers’ annual outing to the seaside, you may observe groups of philosophers rapidly jumping in and out of the sea, to try to see whether it remains wet or not. But they can never be sure it is going to be wet before they jump in, and they can never prove that it is still wet after they jump out.
We might say that it is just common sense to say that the sea continues to be wet when there is no one in it. But it must be admitted that it cannot be proved by sense-experience or observation. It is just much simpler to say that if the sea is wet every time you jump in, it is wet in between jumps. Of course that hypothesis will not work if you only jump in the sea once a year. But if you jump in and out as quickly as possible, it is the simplest explanatory hypothesis to account for why we can more or less predict that the sea is going to be wet.
So we can assume that the sea continues to be wet even when there is nobody in it. Nevertheless, it is probably safer, even if a little more complicated, to say that the sea is such that, if we jump into it, we will find it wet. There is some continuing causal basis for our feelings of wetness, though there is no actual unobserved wetness in the sea. That is what Galileo, John Locke, and John Stuart Mill, all supposed.
Weird science
Bishop Berkeley famously objected to any distinction between primary and secondary qualities. He held, with some justification, that talk about tiny colourless atoms bouncing about is a mere abstraction. Why should we think that such abstractions are real, when in fact this world we observe, with all its smells, tastes, and colours, is the most real thing we know? There is little reason to suppose that science tells us the truth about reality, whereas the senses only provide appearances. It would make more sense to suppose that both science and common sense are concerned with appearances produced by the interaction of a hidden reality with human minds.
Though Bishop Berkeley has become a by-word for silliness among many philosophers, there are things in modern physics that give him some support. The so-called “real world” posited by classical Newtonian science is not only an abstraction. It has passed its sell-by date, and it is nowhere near abstract enough. For quantum science, the world has dissolved into sets of probability waves in Hilbert space, of entangled and superposed wave-particles, and of ten-or twenty-six-dimensional curved space-time manifolds, which probably arise by quantum fluctuations in a vacuum. If you want something abstract, try that on for size.
This scientific view of the real world is about as far from what most people believe, or could even imagine, as it is possible to get. Common-sense consciousness, which is the sort most common people have, experiences things as colourful, tasty, smelly, and wet. Why should we think that the scientific world of probability waves and so on is the real world, as it is in itself when it is not being observed, whereas the common-sense world is just that world as it appears to us?
There is a great deal of controversy about the interpretation of fundamental physics. Some theorists, like Michio Kaku of the City College of New York, one of the founders of string field theory, boldly claim that “the matter in the universe and the forces that hold it together… may be nothing but different vibrations of hyperspace”.1 Superstrings require a ten-or twenty-six-dimensional universe, and the basic forces of electromagnetism, gravity, and the nuclear forces may be caused by the “crumpling” of a universe that exists in dimensions far beyond the four-dimensional space-time of our common-sense observations (not that common sense usually gets even as far as four dimensions).
Other physicists, like Niels Bohr, prefer to think that the world of observation is fundamentally real, and that all talk of such things as hyperspace uses mathematical constructs that cannot be mapped onto any objectively existing reality. In other words, quantum field theory does not tell us what the objective world is “really” like. As Bishop Berkeley suggested, we cannot get beyond a world of appearances, of things-as-they-appear-to-us, whether they appear as sense-perceptions or as mathematical intelligible mental constructions.
After all, probability waves are not actual waves. They are mathematical devices for assigning probabilities to discovering the location of an electron under specific constraining conditions of measurement. You might say that electrons are probably in a number of places at the same time, but they are not actually at any precise place. That is certainly not common sense, and it is very hard to believe. Quantum physics is undoubtedly correct. Its predictions have been verified many times. Yet equally undoubtedly it does not give an adequate description of how things really are. It provides a set of sophisticated mathematical operations for understanding the behaviour of very small energy interactions under controlled and relatively isolated conditions. But one could not say that the variables of the formulae correspond to so-called “real entities”. They are constructions of the mind.
The conclusion, for a number of quantum physicists, is not that there is really nothing there at all. It is that reality is hidden from us in its inner nature. All we can do is construct hypotheses that explain the structure of its interactions with our minds. But if we consider that our minds play a fundamental role in constructing both the sensory world that the senses reveal and the mathematical world that the mind explores, we may be led to the opinion that mind or consciousness is a foundational element of reality. As the eminent quantum theorist John von Neumann put it, “All real things are contents of consciousness.” Bishop Berkeley lives again, as the solid Newtonian world of classical physics dissolves into the abstract mathematical world of quantum theory, and leaves the mind as the most “solid” and basic constituent of the real world.
It is time to pause and take stock. We have already come across three main philosophical opinions about what the world we experience is really like.
First, there is the opinion that the things we perceive are just what they seem to be – warm, wet, fuzzy, and colourful (they might also be beautiful or ugly, ordered or chaotic, pleasant or unpleasant, though that is disputed). The world of sense-experience is the real world.
Second, there is the opinion that our senses disclose only appearances or things as they appear to us. In itself reality is very different, and science and intellectual reflection can tell us what it is like. The world of science is the real world.
Third, there is the opinion that appearance and reality are indeed different. But fundamental science deals in abstract mathematical constructions, and such abstractions do not tell us what reality in itself is like. We do not know what the real world is like. But both sense-experience and science are constructions of the mind, so maybe hidden reality is something like consciousness or mind.
These three philosophical positions, which are basic metaphysical theories (theories about what sorts of things really exist, and what sorts of things are actually real, not just apparent), can be, have been, and still are, ably defended by philosophers. My own preference is for some form of the third view, and I shall try to defend it. The discomfort I feel with Ryle’s philosophy is that it seems to espouse some form of the first view, and this basic (and in my view mistaken) commitment is presupposed in all his specific arguments about the concept of mind. If the third view is right, things will look very different, as I shall show.
What you see is what you get
On closer inspection, the three main views I have outlined split into many further into subdivisions. I will restrain myself and mention only a total of eight philosophical possibilities. No doubt we could think of even more divisions and different kinds of overlap between views – there is probably one sub-division for every philosopher who has ever lived – but eight is enough to be going on with.
The reason why it is important to examine these metaphysical views is that the problem of what persons really are cannot be resolved unless we have first come to a decision about what sorts of things fundamentally exist. Many discussions about the nature of persons fail to tackle this more fundamental question or even fail to see that it is a really difficult problem. Many people just assume some sort of common-sense view, that humans are evolved animals in space and time, and that this three-dimensional world that we experience is what is actually real. Other people, more scientifically inclined perhaps, admit that the real world is very different from the one we see and feel, but it is still definitely and completely material. There are no “spooky” or “supernatural” entities, and Cartesian dualism, in particular, is just a relic of an outmoded superstition.
If we are going to approach the issue rationally, however, we need to see that these are just two out of a pretty large field of possible metaphysical options. In fact, they are both very controversial and highly contested from a philosophical point of view. It is only when we see the wider range of metaphysical options that we realize how tenuous the arguments for common sense and for materialism are.
I am going to argue that the most adequate view of human persons will fall under what I have called the third group of metaphysical theories, which says that there is a reality underlying our everyday experience whose basic character is consciousness or mind. So I need to establish that this is a coherent and plausible metaphysical view. That means setting it out alongside some other major metaphysical views, and showing their strengths and weaknesses. That is what I am now going to do.
The first group of metaphysical theories is the “things are basically what they seem to the senses to be” group. The most radical version of this is the view that when nobody is observing things, when they are not contents of consciousness, there is nothing there. There is only what David Hume calls a succession of impressions and ideas. The idea of a continuing unobserved world is a postulate of the imagination, and, if we were trying to get the simplest possible account of the world, such a postulate would be regarded as superfluous. Things are what they seem to be, but there is no objective continuing world to support the things we see, hear, and touch. If we attend closely to what we experience, we will realize that we never experience unobserved continuing physical objects. So there aren’t any such things.
This extreme position – a sort of radical empiricism, sometimes called phenomenalism (I will call it Theory 1) – is too much for most people, but it makes the point that the common-sense belief that there is a world of physical objects depends upon rational postulates that, strictly speaking, cannot be substantiated simply by appeal to experience. Most people do make such postulates and accept a philosophy of common sense. They assume that things continue to be roughly what they are observed to be even when nobody is observing them. We live in a real world of objects in three-dimensional space, and we observe it more or less as it is (this is Theory 2, sometimes called naive realism, because many philosophers think it really is rather naive).
I think the consideration of properties like colours is sufficient to render this view improbable, especially since we can carry out the same type of analysis for smells, tastes, sensations, and sounds. Nevertheless, I suspect Ryle holds some version of this opinion. At least he speaks as though he does, though to put it like that possibly sounds too “metaphysical” for his taste. Like Wittgenstein, he would probably think that “everything is in order as it is”, that metaphysics raises a host of pseudo-problems that arise from linguistic confusions, and that philosophy can provide no new information about the world, least of all about “ultimate reality”. Philosophy has no theories.
The problem is, that is a theory. And Ryle does, as I have suggested, have some beliefs that fly in the face of common sense – for instance, that there are no objects that are not in publicly observable space (the contents of minds, those “ghosts in the machine”). Common sense says that there are dreams, images, sensations, feelings, and thoughts that are not observable in space. At least my common sense does, and most people I meet down the pub think it does, and if we are not common, who is? Common sense says that things are what they seem to most people to be, but we do not explore too deeply what happens to things when we are not looking at them.
The people who do explore that sort of thing are physicists. Common sense seems to conflict in a marked way with modern physics. This fact leads into the second group of theories about the nature of the world we experience, that science tells us the truth about reality. Modern physicists sometimes say that there are other space-times (“many worlds” or a multiverse of universes), and if so those space-times are certainly not publicly observable in this space. Space and time are only four of many possible dimensions, and physicists like Stephen Hawking envisage realms of being in which space or time does not exist at all or can become interchangeable. It seems to be an open question whether there are non-spatial entities, and philosophers are not going to avoid it by saying that it arises from a logical mistake or category error.
There’s more to life than meets the eye
So we are led beyond common sense toward the currently fashionable position that science tells us about a world that is very uncommonsensical indeed. Because physicists do not like to think of themselves as naive, this is sometimes called critical realism as opposed to naive realism (the unkind term for common sense). The world as it is in itself is not as we observe it in experience. But it has nameable properties such as mass, position, and velocity, and science – preferably fundamental physics – can tell us what they are.
Since the 1930s it has become much more questionable what nameable properties fundamental physics does tell us about. If there is five times as much dark matter in the world as there is matter that we can see, if the fundamental forces of our space-time are in fact crumplings of ten-dimensional hyperspace, and if fields and tensors have replaced particles and waves as the fundamental stuff of the universe, we might well begin to wonder what may be coming next. It sometimes seems that physicists are telling us that something is most definitely real, but we are no longer sure just what it is. This realism is so critical that it seems to have become pretty unrealistic.
This is what I mean by saying that materialism, at least in the sense of saying that everything that exists must have a location and extension in space-time, seems to be scientifically questionable. Many modern physicists have left ordinary space and time well behind. Nevertheless, advances in other scientific areas like neuroscience and artificial intelligence have encouraged a view that all mental events must be identical with spatio-temporally locatable events in the brain. This has led to the adoption of varieties of materialism (Theory 3) which presuppose that, whatever some physicists say, the scientific world is the only one that exists, and the scientific world contains only material entities.
There are physicists who would support materialism in a more sophisticated form (sometimes called physicalism or naturalism), extending the idea of matter (or energy) considerably, but insisting that all that exists must be material in that extended sense. For instance, if our subjective sense of time passing is the result of a crumpling of hyperspace, or even if time is a fourth dimension in some realistic sense, then our consciousness of passing through time may not be a good clue to what reality is like. Time may be there “all at once”, existing from beginning to end as a fourth dimension, and we just seem to be passing through it. For such views our sense of personal development, of having interesting and unique experiences one after the other, is an illusion, as is consciousness itself. Only the material, as defined by the latest scientific theory, is real.
It is not quite clear, however, who would be having such an illusion. Anyway, illusions seem to have some sort of existence. If I seem to see something, there must be something that I seem to see; there must be a “seeming” as well as a “reality”. Or must there?
Headless women
Suppose a conjurer makes it appear that he saws off a woman’s head, and in consequence I seem to see a headless woman. That is an illusion – the head is there, but I fail to see it. I do not in fact see a woman without a head. I fail to see the head of the woman. I do not see what I think I see. So it is not true that if I seem to see X, there must be an X that I seem to see. However, there is something that I see. I see a woman whose head is concealed, but I misdescribe what I see. That is easily done. Conjuring tricks work because they are easily done. We often make mistakes when we describe what we see. Yet there is something I see, even though I have the description wrong.
Compare this with “having the illusion” that I am passing through time, one second after another (whereas, in fact, past, present, and future all exist in one four-(or more) dimensional continuum, and I am not moving through time at all). What is it that I seem to see? One thing happening after another. But could I be describing this wrongly? This would be like saying that time is actually all there “at once”, but I (wrongly) see it as one thing after another. Even if I am misdescribing it, however, I am seeing one thing after another. Someone (me) is having the experience of a succession of times. So a succession of times does exist – in my experience.
That is enough to establish that my experience has properties that objective time does not – properties of temporal succession. Even if time is an illusion, we must distinguish personal experience from objective physical reality. Therefore it cannot be true that personal experience does not exist. Illusions, too, exist, and have properties that do not belong to objective reality.
The extreme materialist view that consciousness is an illusion can only be consistently held by philosophers who are not conscious. Therefore most conscious philosophers who are dissatisfied with common sense distinguish personal experience from objective reality, and maintain that while subjective conscious experiences do exist, objective (unobserved) reality has whatever properties scientists ascribe to it. This is actually what Cartesian dualism (Theory 4), Ryle’s main target, maintains. Conscious experiences are distinct from material objects, and you cannot get rid of them simply by saying that they are illusions.
You could, however, say that consciousness somehow “emerges from” complex physical structures like the brain, even if you have no idea how it does so. This has been termed epiphenomenalism (Theory 5), since consciousness is regarded as a by-product of the physical brain that does not influence behaviour. Descartes did not think consciousness could emerge from matter, since they are so different from one another, and causes, he thought, can only produce effects like themselves. But you could just say that this need not be the case. If one sort of thing (matter) produces another type of thing (mind), there is no point in complaining that we cannot see how it is done. We just have to live with it.
It should be noted, however, that if you say this, you will also just have to accept that matter, or changes in matter, might be produced by minds. So minds could produce physical changes or even possibly physical entities, and again it would be useless for philosophers to complain that they cannot understand how it happens. They will just have to get over it. Mind–matter interaction might be real.
Nevertheless, scientifically minded philosophers often assert that all genuine causes are physical, whereas the personal or mental is a sort of by-product that plays no effective role in governing what happens in the world. This seems to be just a basic dogma – all causes must be physical, because I say so. (I should add that I am not against having basic dogmas. We all have them, but at least we should acknowledge that they are dogmas, and are by no means obvious to everybody.) It is certainly not an opinion that is confirmed by observation or by any natural science. Of course the dogma is not produced by some arbitrary whim. It is produced by the adoption of an elegant and comprehensive explanatory hypothesis – that the unobserved world has the “primary properties” noted by physical science, but no “secondary properties” which belong only to subjective experience. The hypothesis can become very tightly constraining, when it is postulated that the physical world is governed by a simple set of absolute and inflexible laws which wholly determine everything that happens. This is the “machine world” against which Ryle also inveighs. And in that machine personal experiences or the subjects of such experiences become “ghosts”, illusory apparitions with no causal part to play in the workings of the cosmic machine.
The big options
I have now collected five of the eight philosophical views I wanted to outline. Phenomenalism (Theory 1) and naive realism (Theory 2) attempt to maintain that reality is basically what it seems to be to the human senses. The advance of the natural sciences introduces critical realism, and this in turn subdivides into materialist views that mind is not a thing at all (Theory 3), dualistic views that mind and matter are distinct (Theory 4), and epiphenomenalist views that mind does exist, but is a product of and wholly dependent upon the physical world that science correctly describes (Theory 5).
One reason I have listed these views is to make the point that there are many defensible philosophical opinions about the nature of the world we observe and know, and about our own natures as observers and agents in that world. There is not just one obviously true opinion. In fact my suggestion is that the third group of metaphysical theories, which I am just about to embark on, is more plausible than the first two groups. The three members of the third group could be called forms of idealism, which is, in its most general form, the belief that mind or consciousness is more real than matter or provides a better clue to the nature of reality as a whole. If I could establish that, we would be well on the way to showing that human persons are not just complex bundles of matter and molecules. Their moral importance and value lies crucially in their mental lives and acts.
Of course I do not expect to establish it to everyone’s satisfaction. No philosopher ever manages to do such a thing. But I do hope to show that idealism is a coherent and plausible view, fully consistent with the best modern scientific knowledge. And I hope to show that the philosophy of materialism, which is assumed by many to be obviously true, is far from obvious and contains major weaknesses from which idealism is free.
Underlying all this discussion is the belief that metaphysical differences are real and important. Ryle’s claim that he is only rectifying the logic of our language about minds2 by distinguishing logical categories, and not making any statements about the nature of the world, is unconvincing. Ordinary language carries philosophical presuppositions. It presupposes – contrary to what Ryle claims – that minds are causes on occasion, that humans are at least sometimes free agents, and that private states of consciousness exist. If we ceased to believe these things, our language might well change.
Philosophical reflection can make a difference to what we say, to how we speak, and to what we claim to know. The rise of the natural sciences has raised questions about human personhood in a sharp way. It has given rise to radical forms of dualism, which separate minds and bodies completely, and to materialism, which eliminates minds (in this sense) altogether. So another goal I have in mind is to place radical dualism and materialism in historical context as extreme responses to new scientific knowledge, and to point forward to more adequate interpretations of contemporary knowledge.
This of course is what Ryle thought he was doing. He rejected both radical dualism and materialism as inadequate philosophical theories, and tried to replace them with a more rounded view of humans as essentially social animals. In doing this, he was importantly right. His mistake was to think that he had no philosophical theory, but was only stating the obvious (once people got their logic right). But that, ironically, was his philosophical theory.