A review discussion of Introducing Consciousness by David Papineau, but a review with wider implications -- for a kind of Philosophy of Mind. Drawings in the book by Howard Selina. Icon/Totem Books, 175 pp., £8.99/$10.95 13 April 2000 1 84046 115 2
final version of this piece will appear in the July 2000 issue of Journal
of Consciousness Studies.
This short book in a successful series is a good one. You can put up with the drawings on every page, even the quizzically intelligent expressions on the face of the woman butting into your reading-life who looks like the feminist Germaine Greer. Buy the book. It sums up current thinking about consciousness, from a middle distance. Despite Germaine, sometimes hanging out with Descartes, you can see the wood for the trees.
That is not to say the point of view is the only one. It is about as scientific as philosophical, David Papineau being a philosopher of science. A lot of imaginative neuroscience by retired physicists and the like is reported at the end of the book. Could your thought at this moment or your hopeful feeling be microtubules? Those are indeed little tubes in your head and elsewhere in you. Could your thought or feeling be that funny stuff in Quantum Theory -- the stuff taken as having the consequence that Schrodinger's cat is neither definitely alive nor definitely dead until and because someone has a look to see which?
Philosophy of the analytic kind and science have attracted strong supporters and mighty leaders for a long time and are thriving. They clearly have different virtues. The virtue of philosophy is that it is logically more hard-headed than science. The virtue of science is that it knows a lot more about the empirical nitty-gritty of the world. That philosophy is logically more hard-headed has nothing to do with the formulae of Formal Logic. Philosophy is better at keeping its eye on the ball -- when it is good, it is unambiguous. It does not beg questions, and it does not operate with circular or elusive notions. It isn't subjective in an ordinary sense, doesn't run things together, is explicit, is intolerant of nonsense, and attends closely to making all of its propositions consistent.
A prominent part of the current Philosophy of Mind has been a little infected by science, notably Cognitive Science but also physics. It has been both computerized and made curiously speculative. Does it not have so much of the virtue of philosophy generally? We can do with a test case. One is provided by Introducing Consciousness. For a start, is it a little too inclined to predispose us in a certain direction by several means other than argument and evidence?
We are told that our subject is `the felt nature of consciousness'. (p. 8) This is said to be exemplifed by the pain of having a tooth drilled without an anaesthetic and the look of a red rose (p. 3, p. 61). Our subject, again, is the fact that `conscious states feel a certain way', `the feelings involved'. (p. 7, p. 21) We are concerned with `something about experience' -- conceivably as distinct from experience itself. (p. 14)
So is our subject an aspect or property or side of consciousness generally? Better, a class of aspects, one kind of ways in which conscious states are different from one another? It can certainly sound as if this is the subject. It's feels and looks, the side of consciousness somehow owed to sensation and perception, including dreams. It's `qualia', although that term so much heard of in the recent philosophy of mind is for some reason not used here.
Our real subject of course is not an aspect -- but the nature of consciousness, the fundamental fact of it, as the title rightly implies and the author says in other sentences. Still, the ambiguity lingers. What it does, with innocent persons who haven't sorted it out, is to predispose them in the direction of a pile of materialistic doctrines said to be about consciousness but which certainly seem to leave it out. The innocent persons, maybe including an author or two, half-suppose it's not so bad if the doctrines just leave out an aspect of consciousness -- this leaves it possible for the doctrines to be OK about what really matters, OK about the nature of consciousness.
They need to see clearly that what the pile seems to leave out is the real subject-matter, indeed the only subject-matter on the agenda. Feels and looks is a side-issue, of course, because they aren't all of any conscious state, and because there are perfectly good conscious states that don't include any feels or looks at all, anyway any distinctive ones. There aren't any of them discernible by me when I think that something called Neural Functionalism is a mistake. Thinking in general, pure thinking taken by itself, doesn't have feels and looks worth mentioning. Its reality for us is quite something else.
Before coming on to some other predisposing activity, let us glance at a related matter. We are often reminded in Introducing Consciousness of Thomas Nagel's famous line, anticipated by Timothy Sprigge, that there is something it is like to be a bat. There is something it is like to be getting around by means of echo-location. Are we also supposed to take it, more generally, that all states with feels and looks are ones such that there exists what it is like to be in them? That we get a first understanding of this side of consciousness in this way? (pp. 10-14) That the words do not just gesture at it, but are a start on analysing it? Or, is talk of `what-it's-likeness' (p. 15) to be taken as some gesturing not just at the side of consciousness, but the whole general nature of conscious states -- a first understanding or analysis of that?
Whether a side of consciousness or its nature is in question, it can seem there is little advance in understanding, but much circularity instead. Saying that there is something it's like to be a bat just comes to saying, doesn't it, that there is some kind of consciousness that bats have? That is no analysis of their or anybody else's consciousness. If the words `there is something it's like to be a bat' are being used in some extraordinary way, what is it? As for saying about conscious states in general that `there is something it is like to be in them' -- doesn't that come to saying, at best, that there is what it is like to be conscious in them? That is no help as a definition of consciousness. Again the term to be defined turns up in the definition.
Does the further mouthful that `conscious states are "like something"', that there's something it's like to be conscious, actually have to do with a comparison with something other than conscious states in general? (p. 15) What could that thing conceivably be? Presumably not the microtubules? They're not at all like the conscious states in general. Presumably not, either, the collapsing wave functions that did in the cat because somebody had a look? The only like sort of thing that comes to mind as like is conscious states additional to the conscious states in general. That is another circular disaster, even nonsense.
So the shepherd's flock needs protection first from the idea that the real issue of consciousness is a side-issue, and then from the idea that certain mouthfuls are a start on an analysis. They also need protection from something else. It is that the subject actually in hand, the nature of consciousness, is in a certain way unimportant. They could fall into thinking it is something of which the best you can have is a `subjective' view. (pp. 10-14) It's what's left over after you spend time on the important business of getting an `objective' view of consciousness. It's what escapes `objective definition' because it's `something ineffable'. (p. 8) So you'd better stick to thinking about the objective side of things, starting with the brain itself. The microtubules again. (p. 10, pp. 12-13, p. 127)
Well, so far as the given reason having to do with this subjectivity is concerned, there's no need to give over thinking about consciousness. It's not true that trying to find the real nature of consciousness is trying to convey to somebody else what nobody else can have, at least not yet, which is your own private experience. Whatever obstacle there is in the way of that, probably temporary, whatever this particular fact of subjectivity and the rest of consciousness comes to, the job in hand is precisely that of being objective about consciousness.
It is noticeable that no definition of objectivity is supplied to us in Introducing Consciousness. Could objective propositions be ones whose subject-matter can be seen and touched by all of us or at any rate more than one of us? That would have the intolerable upshot of making propositions about atoms subjective. Could objective propositions just be the scientific ones of the age? (p. 14) Well, if it really were true that consciousness itself could not now be investigated scientifically, would it follow that we ought to give up the subject? Pretend that it doesn't exist, that we're real zombies? Why should we do that, shepherd? In fact, to cut this story short, a useable definition of objectivity is one tied to common tests for truth, and it makes trying to get to the nature of consciousness exactly an objective business.
Something else lies behind this third way and also the first way in which a shepherd can be careless with his flock. Again it is something like an ambiguity. In fact our subject is not four things. It is not consciousness + the purely neural or brain facts that go with consciousness + the causes of consciousness + the effects of consciousness. But there is certainly a tendency in Introducing Consciousness, as in so much current Philosophy of Mind, to think that this large bundle is our subject. (p. 10, p. 13) There is a tendency to regard consciousness itself as just an `ingredient' in the subject. (p. 7) There's `the conscious pain' and the `conscious visual experience', so presumably there are also the other ones -- the neural pain and the neural visual experience. (p. 1) There's the `subjective' side of consciousness and there are the three `objective' sides.
Well, anybody can think of anything they want, but if they are thinking about what we take to be consciousness itself, they aren't thinking about the three other things. What my elbow does, for a start, is not part of my consciousness itself. We don't usually run these four things together, although it's unkindly said we do, and certainly we don't have to. (p. 14) The important point here is again not a matter of argument strictly speaking. It is that people can drift into thinking that a pile of materialistic doctrines is pretty good on three-quarters of a subject -- and therefore that not doing well with the last bit, even missing it out, is tolerable. Just one `ingredient' missing. But that's not the situation at all. If the subject is supposed to be and is said to be consciousness, and the pile leaves all of that out, every last scintilla, the pile is a disaster. Even if it's the cat's pajamas with respect to the three other quarters of a bundle.
When you get started on clearing things up in the scientized philosophy of mind, it's hard to stop. So let me tell you that when we stop being distracted by the side of consciousness that is feels and looks, and give up the mouthfuls about `what-it's-likeness', and escape the stuff about mere subjectivity, and also the bundle, and then are reading on clear-headedly, something else happens. When we are concentrating on the nature of consciousness itself, Germaine herself butts in with some of her many helpful lines.
She lets us know, about this question of what consciousness is, that in particular it is the question of `how it relates to scientific goings-on in the brain'. (p. 15) It's the question of `where the feelings come from'. (p. 21) It seems Germaine wrote the jacket of the book too, which says it's all about `the source of conscious feelings', the `relation between mind and matter'.
But if you go by the title, and if the subject is consciousness, it's not necessarily about that brain-consciousness relation at all. Suppose you believe, as all of us do except in weak philosophical moments, that consciousness isn't the cells of our bodies, neurons in particular. Then you've got to try to say what it is. And this isn't at all the question of how it is related to the cells, of its general source in them or dependency on them. I couldn't get Sir Roger Penrose of the microtubules to see the difference in a radio programme, but it's really there. It really is, Rog. Of course you do answer the question of how consciousness is related to the brain if you say it just is the brain -- has only neural properties. But if you don't say that about the nature of consciousness, Germaine's question isn't even on the agenda. That's some other meeting.
When we do get to the question of the nature of consciousness, we hear familiar words in the different answers to it that are contemplated. Consciousness, according to one answer, is `genuinely distinct' from brain activity. (p. 16) Consciousness is `separate from' brain activity. (p. 25) They're not a `unity', not `identical', not `the same thing'. (p. 17, p. 112, p. 56) All this raises a question. What is the `genuine distinctness' in question? What is the `unity' in the opposite answer? Evidently `dualism' asserts genuine distinctness and the like, and `materialism' asserts unity and the like, but what are genuine distinctness and unity?
Typically in the current Philosophy of Mind we aren't told. This makes for trouble. To mention one thing, the possibility is sometimes left in play that the unity is just psychoneural lawlike connection -- mind and brain going together as a matter of scientific law. But then the so-called materialism can in fact be what has always been regarded as a dualism. Consciousness can be connected with the brain in the given way but itself be entirely non-neural. The same is true if conscious thought and neural process are parts of the same whole. If our author does not add to the carelessness here, might he have done more to reduce it?
Might he also, by the way, have given even less attention than in fact he does to what is first presented as a third option on a level with dualism and materialism? That is the elfin notion that the problem of consciousness, or maybe of the brain-consciousness relation, is insoluble and will remain a mystery -- essentially because of some general proposition to that you can't see how grey stuff can cause coloured stuff. (p. 18, p. 110) Plainly it's going to be a considerable surprise for the elf when his first grey matchhead bursts into flame.
In fact materialism so-called, or physicalism or mind-body identity theory or monism so-called, properly divides up into two kinds. One kind says that in your seeing or thinking something, there is just one internal event, and it is both neural and conscious. It has those two different characters or properties. Donald Davidson's Anomalous Monism comes here. Views of this kind, plainly, are really property-dualisms. They involve two of something, indeed two realms. That is not what is wrong with them. There's nothing bad about a number. What is wrong with them is that these false materialisms do not explain the consciousness they take to exist. They do not give us its nature. This question gets lost or downgraded. The other materialisms, with a true claim to the name, say something very different. It is that with respect to your thinking or seeing something a moment ago, that event had only neural properties.
The leading doctrine in the emptying circle of the orthodox philosophy of mind comes here, although it denies it. Neural Functionalism supposes itself to add something significant to earlier real materialist accounts of our human consciousness and the consciousness of other biological creatures. It adds that your bit of thinking or seeing, or your wanting a glass of wine, had certain causes and had certain effects, and that these were its essence. These effect-and-cause properties of the event, `structural properties' as Professor Papineau names them, made it a conscious event. (pp. 45-49, p. 58, p. 86) What makes something a desire of yours is not what it's in, the neurons, but what gave rise to it and what in turn it gives rise to. A desire, very roughly speaking, is whatever comes from perception and results in behaviour.
It seems to me that this thought about realization of the essential event of your desire in neural stuff, rather than in the silicon of computers or whatever, is only a distraction, like the general proposition of what is called the variable realization of conscious events. If you say my consciously registering Germaine's quizzical expression again was a wholly neural event in my head with certain causes and effects, you do not add a whit more to your account of it, of what it is, by saying that it could have been a silicon event and it would still have been the conscious event it was if it had the same causes and effects. You don't find out more about your Volkswagen by finding out you could have got to Brighton if it was plastic instead.
Introducing Consciousness is tolerant of Neural Functionalism initially, and tries to give it a hand with a certain difficulty. It's the difficulty of whether Neural Functionalism is in fact a version of Epiphenomenalism. That is the desperate theory of 19th Century neurophysiologists, and two or three equally desperate successors, that our conscious lives do not cause our actions at all -- our conscious desires are no part at all of the explanation of why our actions happen. Is Neural Functionalism an Epiphenomenalism -- since for Neural Functionalism it's what Professor Papineau named `the structural properties' that are your conscious desire but it's probably the neural facts that cause your arm movements and the rest?
Professor Papineau wonders at this point (p. 78) if the Neural Functionalist could insist it was `the structural properties' of the desire that cause the arm movement. That may be scientific thinking, but wouldn't it make things still worse for Neural Functionalism? What was it to to be a `structural property'? Well, it was just to be a certain effect-cause. It was to be a cause of the arm movement among other things. In which case Neural Functionalism, in even thinking about escaping Epiphenomenalism in the given way, is in danger of uttering quite a sentence, too much for me. It will have in it as one part that `the arm movement was caused by something's causing the arm movement'. Not good at all.
Whatever is to be said about its Epiphenomenalist tendencies, the clear fate of Neural Functionalism is that it runs up against something. That is The Wholly Resilient Proposition About Consciousness. It is simple. It is that the properties of conscious events aren't neural ones. Consciousness isn't cells. The proposition recovered its strength and defeated the corpuscular materialism of Thomas Hobbes in the 17th Century. It also did in early neurophysiological materialism in the 19th Century, and eventually made Behaviourism dead as a doornail in the 20th. It will do in Neural Functionalism early in the 21st. But no doubt you would like to hear an argument for it, since it just is what materialism tries to deny. Professor Papineau mentions two familiar ones.
The first, owed to Frank Jackson, is that Mary in a black-and-white environment from birth, where she learns all the neuroscience of colour-vision, would discover something new when she got out and saw red. Anyway at first sight, what the argument depends on is the Resilient Proposition, and more particularly that some perceptual consciousness is other than purely neural activity. The Mary argument fails if you deny that, as some characters have in defence of the theory. Nothing much is added to the Resilient Proposition by dragging in knowledge of the brain activity and of the consciousness. Take your proof or conviction that this isn't that. You don't add to it by preceding or following it with the thought that someone could know that this isn't that.
Another recent argument against Neural Functionalism, given by Saul Kripke, is that there could be a thing with all our standard neural equipment, fully functioning, and yet not conscious -- the zombie. This is a logical possibility, as distinct from a nomic possibility or a possibility in terms of law. The argument has its own considerable obscurity, having to do with what follows from a logical possibility. It seems to me to add little to the Resilient Proposition.
To my mind, the Mary Argument and the Zombie Argument are reassurances or heuristic devices rather than arguments or proofs. Still, attempts have been made to undercut these reassurances, one in particular. Stripped down, and applied to the Mary argument, it is that when she gets out and sees red, Mary doesn't really discover anything new. What happens is not that the world comes to have a new property in it for her, but she gets a new concept for an old one -- for some reason called an `imaginative' concept. (pp. 100-103) Seeing red still is just those boring old cells, which now fall under the concept seeing red.
This is more or less identical to a line taken by Identity Theorists a few decades back, based on Gottlob Frege's hallowed distinction between the sense and the referent of an expression. He said `The Morning Star' has a sense different from the sense of `the Evening Star', but they stand for the same heavenly body. The Identity Theoriests said `seeing red' does have a different sense from `that neural activity', but it has as referent the same one thing.
Here is a rejoinder. We have it that there's this subject-matter and we can conceive of it or describe it either as `seeing red' or as `that neural activity'. Both conceptions or descriptions are true of it, of course, as has to be granted and is. Each one does indeed designate a property of the thing. It's not as if `seeing red' is true of nothing, obviously. But the expressions say and mean quite different things. In which case there are two properties in question, not one. So the Mary story remains as good as it ever was in reassuring people that consciousness is other than dopamine and electrical potentials, not to mention the microtubules.
So is it possible to prove or confirm the Resilient Proposition? You may well not feel the need of a confirmation or proof. Scepticism about the existence of consciousness -- something other than neurons -- seems to call for even less of one's philosophical attention than scepticism about the external world, something existing outside my head. You may say, too, that it's pointless to try to provide a proof of the existence of consciousness. A proof requires a premise -- a proposition firmer than the one that is the conclusion. Can there be one of those with respect to the putative conclusion we know so well, that consciousness isn't cells?
Let us not delay, but let me say that the Resilient Proposition got its first piece of support for each of us when we first distinguished between milk and our idea of milk. Later we put our bodies in the category with the milk, and then a lot later our bodily cells, and remained as confident about distinguishing between them all and any consciousness. You could say, a little pompously, that something like the Resilient Proposition is a foundational or structuring fact of our thinking lives.
Of course the proposition that consciousness isn't cells leaves us with big problems, of which the biggest is is saying what it is. What is it to be conscious if it's not just having some cells? David Papineau looks at traditional dualism. It comes in two kinds, not sharply distinguished by him, the first being that consciousness consists in stuff in our heads that is non-physical -- `mind-stuff'. (p. 50) Those who hold to this dualism, if they still live and breathe, suppose at least that the stuff is not in space.
Professor Papineau is remarkably tolerant about this nonsense. For a start, how can something not be in space but be in a head? And what is it for anything whatever to exist if it is not in space? Certainly we need to know. There is also the question of how the mind-stuff can be an effect and cause of ordinary physical events -- first a wine bottle on the table and then later its being empty. This problem, the curse of dualism, goes back to Descartes.
You can do yourself a little good, if you feel driven to stuff about stuff-in-the-head stuff as the nature of consciousness, by doing some of that more hard-headed thinking that characterises philosophy as against science. The problem on the table is that of how there can be interaction between the funny non-physical stuff in the head and the physical realm. You can ask a useful question. What are physical things? What is the physical realm? Let us say that the physical realm has in it chairs etc. and atoms etc. -- a category of space-occupiers perceived by people generally and a category of space-occupiers that cause perceived space-occupiers. But then, to come to the nub, why shouldn't the stuff in the head be physical -- go into the second category? It can be physical but non-neural. This is the second version of traditional dualism. Consciousness is physical but non-neural stuff in heads. The doctrine is not nonsensical, but it certainly has a real problem.
The real problem is not the interaction problem, of course, but something else. What the doctrine contemplates is that consciousness is not neurons as we know them, but other physical stuff that will be discovered by some future neuroscientist. The problem is that we can already be certain, right now, about what will be heard just after the Nobel Prize ceremony. It will be from some Bolshie philosopher speaking on behalf of everyone. The proposition will be about this new stuff in the head, which of course is something like the present stuff of neuroscience. The proposition will be that consciousness isn't that stuff. The proposition will be a slightly enlarged version of the Resilient Proposition.
The Bolshie philosopher may add, for good reason, that it doesn't seem to us, on reflection, that consciousness is anything that is in a head. My being conscious right now, if I think about it, isn't any such thing. This is a point of large importance, separate from the one about stuff or kind of stuff. So it seems some very different idea of consciousness is needed, neither the materialism or the dualisms.
But let us linger for a moment to reflect on another point having to do with philosophy and science. Professor Papineau, as remarked already, is remarkably tolerant of nonsensical dualism, the first sort. It helps that he has an odd idea of the curse of dualism, taken as the problem of how non-physical events could interract with the ordinary world. This has been known as the Mind-Body Problem. As you have heard, it has been the problem of how such physical items as wine bottles and images on retinas and neural activity can cause desires and thoughts and the like, and how the latter non-physical things can cause arm movements and bottles being empty.
Professor Papineau sees the problem as one posed by a certain proposition. It is that physical events have only physical causes. This is called by him the causal completeness of physics. (p. 65, p. 67) This view of the Mind-Body Problem, the curse of dualism, is offered by Professor Papineau to an up-to-date `mind-stuff' dualist as a great help. All the dualist has to do is put up with the embarrassment of becoming an Epiphenomenalist as well and he can thereby escape the curse of dualism. If the non-physical stuff of consciousness is just side-effects, with no causal power, then it remains true for the dualist that all physical events have only physical causes.
But of course for the rest of us, not informed about physics, Epiphenomenalism seems to pose just the very same problem as would be posed by the non-physical events causing limb movements. Indeed this Epiphenomenalism poses the first half of the Mind-Body Problem as traditionally and still stated, as it was above: how can external and bodily events give rise to consciousness conceived this way, and how can the non-physical consciousness give rise to physical events? The first half is the difficulty, to say the least, of effects that are nowhere.
Epiphenomenalism plainly does pose this hardest of problems. Evidently it is not owed to the proposition of `physical event, physical causes' -- physical events have only physical causes. So in this case science has made no very useful contribution to philosophy, but has only saved a dualism from a lesser problem -- one, by the way, that could do with some examination that it cannot have here, having to do with its unspecified conception of the physical. So what does make for the large Mind-Body Problem? Well, obviously, you could say that you can't have either a cause or an effect out of space -- or one out of space and one in. We'll come back to that briefly.
Let me sum up. When you go in for the hard-headed thinking, it is clear that the false materialisms don't really attempt an answer to the question of the nature of consciousness. As for such real materialisms as Neural Functionalism, they run up against the Resilient Proposition that will always defeat them. Being conscious isn't being in a neural state. It's not cells. And we can't have any hope for dualist ideas of consciousness being somehow actual stuff in our heads, either non-physical or non-neural.
As for Professor Papineau himself, he makes it pretty clear he is not the kind of real materialist who is a Neural Functionalist. He also seems to make it pretty clear he is some other and simpler kind of real materialist. (pp. 96-112) He seems to be an Eliminative Materialist -- Thomas Hobbes of the 17th Century reborn in time for our new Millennium. He makes a meal of saying that if you say consciousness is cells you don't eliminate it, but say it really exists -- as cells. (p. 84) It seems to me you can have fairies at the bottom of the garden that way, and rain-dances that really work. If you say Elvis Presley is now just our memories, you can also say in this way you don't eliminate him, but make him really alive and well -- as memories. That might be a way of being alive and well in Quantum Mechanics. It's not so good, is it, in the rest of the world?
It is true that Professor Papineau is at least a little uneasy, not an unreflective real materialist. He sees the need for some improvement on real materialism, but leaves it to late in his book to get into much useful action. But there is another alarming question. He seems to be a simple real materialist, but could it be that he is not a real materialist at all?
On one page he braces himself to tell us what the doctrine he seems to favour actually is. It is that conscious experience, say unpleasant feelings, `are nothing different from the relevant brain states. To be in pain is simply to be in a certain brain state. That's what it is "like for you" if you are in that brain state'. (p. 84)
Put aside entirely my sceptical thoughts earlier on `what-it's-likeness'. The quoted sentences are still remarkable ones, maybe an indication of the instability of real materialism in the lives of those who are drawn to it by science. From the sentences we learn the proposition that to be in pain is simply to be in a brain state and nothing different from that. Is something added to this proposition when it's then said that being in the brain state is there being something it's like for you? Who knows? The mouthfuls aren't clear enough to settle the matter. We do know what would be the result of really adding something to what presumably is still simply and brain state and nothing different -- self-contradiction.
Similarly, on another page at the end of the book, we have it that consciousness, for materialism, `isn't any extra "mind-stuff", in humans or elsewhere. There are just physical processes, some of which are "like something", for the creatures that have them.' (p. 168)
Again put aside my earlier scepticism. The second quoted sentence says, doesn't it, that there are processes that (a) are only physical ones in the brain and (b) are `like something' for the owner. Does (b) assert the same as (a)? Clearly not. there presumably wouldn't have been any point in adding it if it did. In which case doesn't (b) contradict (a)? Isn't the second quoted sentence a self-contradiction?
You'll have to settle the problem of Professor Papineau for yourself -- the problem of what he believes. As for me, it's impossible to escape the feeling, on the basis of this good book and others, that somehow we need to look at the problem of consciousness wholly differently. In this new millennium we need to start up the philosophy of mind again, start it up in some radically different way.
One very different idea is Consciousness as Existence. It is about perceptual as against reflective or affective consciousness, and involves the hope that they will one day be analysed in terms of it. Here is a quick sketch of the idea.
What is it for you now to be perceptually conscious? What is it for you to be aware of the room you're in? What does that come to? Isn't it for a world somehow to exist -- for things somehow to exist in space and time? Isn't that about right? Your being conscious of the place is not something in your head, but this world or state of affairs.
Is the answer just about "a mental world"? Is this another false hope, then, something that in fact is just circular and non-analytic? To see, think again of the physical world as defined earlier. It consists in chairs etc & atoms etc. -- the category of generally-perceived space-occupiers and the category of space-occupiers causally connected to things in the first category. Compare just the generally-perceived part of the physical world with the above world of you in your room.
The generally-perceived part of the physical world is dependent on its other part (atoms etc.) and also on perceivers generally. It is partly owed to our not being bats. The other world whose existence is your now being perceptually aware is interestingly similar: it is dependent on the other part of the physical world and also on you in particular. If the dependency on perceivers in general of the perceived part of the physical world does not turn it into a mental world, which it doesn't, why should a related dependency on you turn into a mental world the world whose existence is your now being perceptually aware?
This idea of Consciousness as Existence satisfies a number of criteria, one or two noticed already, for a good answer to the question of the nature of perceptual consciousness.
(1) The idea of Consciousness as Existence is true to what is misleadingly called the `phenomenology' of consciousness -- what it seems like or seems to be. That is an excellent start, partly since really there isn't more to consciousness itself than there seems to be. It itself has no part hidden from us.
(2) The idea makes perceptual consciousness into a reality, which we are certain it is.
(3) The idea gives actual content to our conviction that our being conscious is in some important sense something subjective. On the idea in hand, it consists in something different from the physical world, but not far off. As remarked earlier, a subjective world of this kind is something we can in another sense be perfectly objective about.
(4) The idea of Consciousness as Existence at least does not worsen the problem of mind-body interaction, the curse of dualism. The curse of dualism in fact is its putting your being conscious out of space. This idea doesn't. It succeeds where real materialism also succeeds, as well as where materialism doesn't.
(5) Finally, any idea with a chance of lasting must be in accord with The Wholly Resilient Proposition. Certainly Consciousness as Existence is.
(6) Is there a troublesome criterion of a good idea of consciousness that has to do with the intentionality or aboutness of consciousness? Philosophical accounts of intentionality are pretty much a mess. Ideas of consciousness don't have to satisfy them -- that little industry is best abandoned in the new start we need to make in the philosophy of mind. In so far as there are pre-philosophical considerations of aboutness that need to be satisfied by a good idea of consciousness, it is arguable that Consciousness as Existence does satisfy them.