Section 5: Conscious Experiences
(This section was written in 2004-
It is often claimed that consciousness is, scientifically speaking, still a mystery to us. We can understand how the universe evolved after the first fraction of a second following the Big Bang, how the physical world around us depends upon the actions of the smallest elementary particles, and even how life itself originated and led to all the living creatures on Planet Earth. But we are still at a loss (so it is claimed) to account in a scientific manner for the phenomenal 'feel' of our visual, auditory, and other experiences. Now this may appear to be a gross exaggeration. After all, it seems obvious from our existing scientific knowledge that conscious experience has to do with our brains; and this knowledge has substantially increased over the last few decades as a result of imaging studies of brain processes, investigations of humans with cognitive deficits, lesion studies on animals, etc. However, it is one thing to know that there exists some sort of relationship between what we experience and what goes on in our brains, and another thing to understand how or why that relationship comes about. For example, the brain and its parts and processes have none of the qualities that we come across in our everyday experiences: I can be looking at a painting full of greens and blues, yet nothing that I can investigate in the brain seems at all similar to such colours. This is the sort of difficulty that makes many people wonder just how a grey, wrinkled object with the consistency of chilled butter (Carter 1998) can be responsible for all of our conscious experiences and our abstract thoughts. To repeat a frequently used quotation from T. H. Huxley (cited in de Quincey, 2000): 'How it is that anything so remarkable as consciousness comes about as a result of irritating nerve tissue is just as unaccountable as the appearance of the Djinn, where Aladdin rubbed his lamp ... .' Hence, it is claimed that there is an 'explanatory gap' between our phenomenal experiences and our knowledge of the physical world.
In what follows, I want to develop an understanding of our conscious experience that is based on the writings of Daniel Dennett, and then to defend such an account against the arguments of critics such as David Chalmers. The discussion will largely follow Dennett and Chalmers on their own terms, as it were. However, a number of the themes that I examined in the previous section, relating to emergence, hypostatization, and the nature of explanation, will surface as we proceed, and hopefully throw fresh light on the debate.
The difficulties encountered in trying to establish a direct link between conscious experience and neurophysiological facts led to the idea that the contents of our phenomenal experiences are determined by the functional role played by our mental states. This approach also had the advantage that it allowed for, at least theoretically, the existence of consciousness in non-
Thus characterized, functionalism has been subject to strong attack, for example by Putnam (1988) and Searle (1992). One major problem is that the assignment of functional roles or computational states is entirely observer-
But where then do we look for an explanation of the nature of our conscious experience? My account will start by building on suggestions made by Daniel Dennett in Consciousness Explained (1991). Dennett is usually seen as offering up some form of functionalist account, but he himself (1991, pp. 459-
2 Dennett's Explanation of Consciousness
In his discussion of what it is we are doing when we have conscious experiences, Dennett (1991, p. 113) concentrates on our discriminations and detection of features. It is key to his model of how the brain works that it is only necessary for a discrimination to be made, or for a feature to be detected, once; there is therefore no need for what we might term a 'master discriminator'. Instead, the various content-
... parts of the brain are caused to go into states that discriminate different features, e.g., first mere onset of stimulus, then location, then shape, later color ..., later still ... motion, and eventually object recognition. These localized discriminative states transmit effects to other places, contributing to further discriminations ... (Dennett 1991, p. 134).
Dennett therefore emphasizes that what he is talking about is an extremely large number of small-
Firstly, these microfunctional activities constitute consciousness, rather than leading to consciousness in a causal or emergent manner:
Conscious experience, in our view, is a succession of states constituted by various processes occurring in the brain, and not something over and above these processes that is caused by them (Dennett & Kinsbourne 1992).
Secondly, conscious experience is not unitary: 'Perhaps the various phenomena that conspire to create the sense of a single mysterious phenomenon have no more ultimate or essential unity than the various phenomena that contribute to the sense that love is a simple thing' (Dennett 1991, p. 23).
Thirdly, Dennett (1991, p. 64) is of the view that, in order to avoid circularity, an explanation of consciousness cannot itself make use of conscious experience. The example he gives is that if we are asked to provide an explanation of the experience of pain, we cannot use the awfulness of pain as part of our answer. The awfulness is part of the description of that which is to be explained, rather than part of the explanation. To confuse the two would leave us with an undischarged virtus dormitiva:
To me one of the most fascinating bifurcations in the intellectual world today is between those to whom it is obvious -
Fourthly, there are no such entities as qualia. Dennett's view (e.g. 1991, p. 322) is that since the discriminatory micro-
If your model of how pain is a product of brain activity still has a box in it labeled 'pain,' you haven't yet begun to explain what pain is ... Surely life can be explained in terms of things that aren't themselves alive -
These points reveal that a key element of Dennett's explanation of consciousness is to argue against its reification. Referring back to my earlier discussion of hypostatization, we might say that consciousness is something that we do. And we do it as the particular type of living entity that we are. We should therefore not hypostatize that activity as a thing or a property that is caused by, or somehow inheres in, our mental activity or brain states. This can, I think, be seen in Dennett's comment (2001) that 'Functionalism is the idea enshrined in the old proverb: handsome is as handsome does. Matter matters only because of what matter can do.'
Having characterized Dennett's position, I will now turn to those critics who object that his explanations effectively deny that we have conscious experiences. I will start by noting that Dennett often talks in terms that clearly accept that conscious experience occurs. For example, he discusses (1991, p. 45) one of his earlier articles and says that he was caricatured as saying that there were no experiences: 'I wanted to say, "It turns out that the things that swim by in the stream of consciousness -
There are, I think, two main reasons why Dennett is often taken as denying that we are really conscious. The first is his insistence that we should not reify consciousness, and the second is his commitment to a method for the scientific investigation of consciousness that he terms heterophenomenology. Let's take them in reverse order.
Dennett sees the need for a methodology for the scientific study of consciousness that takes account of (i) the well-
Heterophenomenology is therefore a methodology for utilizing reports about phenomenological experience, without making any underlying assumptions about its constitution or causes. Some such methodology is required if we are to investigate consciousness scientifically:
But scientists have always recognized the need to confirm the insights they have gained from introspection by conducting properly controlled experiments with naive subjects. As long as this obligation is met, whatever insights one may garner from 'first-
Heterophenomenology therefore provides a bridge between the expression of phenomenal judgments and data concerning brain states, etc. As such, it is a methodological principle for scientific investigation; a critic may argue that it is not appropriate in all circumstances, but I cannot see how it implies that we are not actually conscious.
Now let's turn to Dennett's stance against reification of our conscious experience. He resolutely refuses to accept terminology that he believes betrays a commitment to any form of dualism. So he says (1991, pp. 364-
[Some commentators] seem to think there's a difference between thinking (judging, [etc]) something seems pink to [them] and something really seeming pink to [them]. But there is no difference. There is no such phenomenon as really seeming -
He adds that there is therefore no 'actual phenomenology'. I think he says this because he believes that there is just (i) the content-
It ought to be evident from what I have said so far that Dennett is primarily concerned with the discriminations and feature-
... if you carefully dissociate all these remarkable functions from consciousness -
But does Dennett have a problem with conflating 'functions' from a first-
Searle goes on to criticize those who believe that there are two interpretations of terms such as 'pain' or 'belief', one where they refer to non-
Of course, we cannot simply equate the functionality that we identify from our own subjective perspective with functionality as described by cognitive science. We might believe that, from an epistemological standpoint, the attribution of certain types of functionality to another creature, whether carbon-
3 'The Explanatory Gap': A Summary of Chalmers' Criticism of Reductive Accounts of Conscious Experience
One of the most effective critics of reductive accounts of consciousness is David Chalmers, and I therefore want to see how my characterization of consciousness as microfunctionalism might fare under the weight of Chalmers' reasoning. The arguments that Chalmers uses have, in general form, been around for a while -
Chalmers starts by saying that he wants to 'take consciousness seriously'. By this he means that he wants to explain the phenomenal experiences that we actually have, rather than the mental processes or functions that serve as explanations for our behavior (e.g. 'attention' or 'memory'). In other words, he will maintain the distinction between the phenomenal concept of mind and the psychological concept of mind. He notes that one (mistaken) strategy for understanding consciousness is to explain one or more cognitive functions in psychological terms, and then to gloss over the conflation between phenomenal states and psychological states.
Chalmers then sets out the notion of supervenience: B supervenes on A if it is the case that, once you know the A-
Now, a reductive explanation is an explanation in terms of simpler properties or entities. When some phenomenon is logically supervenient on certain low-
His analysis of the notion of logical supervenience allows Chalmers to conclude that there are three ways of establishing the claim that logical supervenience holds in a particular circumstance, and therefore three types of argument which might establish that consciousness is not logically supervenient on the physical. Such arguments might be based on:
(i) Conceivability. We may be able to conceive of a situation in which the physical facts remain the same, but where the phenomenal facts differ. (It is important not to misunderstand the definition of conceivability that Chalmers is using here, namely 'a statement is conceivable ... if it is true in some conceivable world' (1996, p. 66); it does not mean 'I can conceive of it being true [for all I know]'.)
(ii) Epistemology. If logical supervenience holds, then the implication from A-
(iii) Analysis. The a priori nature of the entailment means the B-
Chalmers' specific detailed arguments are:
1. The logical possibility of zombies, defining a 'zombie' as a being that has all of my functionality but no phenomenal experience; (an argument based on conceivability).
2. The logical possibility of an inverted spectrum, i.e. that I might have a phenomenal experience of seeing red in the same situation in which you experience blue; (another argument based on conceivability).
3. Epistemic asymmetry. Our knowledge about phenomenal experience is obtained mainly from our ourselves, rather than from the external world or other people; (an argument based on epistemology).
4. Jackson's argument about Mary, the cognitive psychologist who has never seen any colours; (another argument based on epistemology).3
5. The apparent impossibility of analyzing phenomenal experience in terms of anything else, due to its ineffable nature; (an argument based on analysis).
For Chalmers, these arguments establish that consciousness does not logically supervene on the physical and therefore that all reductive explanations must fail. Facts about phenomenal experience are not reducible and in this sense they are 'additional facts'.4
Chalmers sees it as straightforward to extend this epistemological argument concerning explanations to the ontological conclusion that materialism is false, i.e. that 'there are features of the world over and above the physical features' (1996, pp. 123-
Of course, each of Chalmers' arguments that I have noted above have been subject to criticism. I do not, however, intend to examine these specific arguments in detail, since I feel that the most important issues are to be found in the general considerations that lie behind them, and it is to these more general issues that I turn next.
4) The Discussion about Structure
(a) The basic argument
Chalmers (1999b) contends that similar intuitions underlie all of the above-
(1) Physical concepts are all structural-
(2) If [X] truths are to be entailed a priori by structural-
(3) There is no analysis of phenomenal concepts in structural-
(4) Phenomenal truths are not entailed a priori by physical truths.
Chalmers (1999a) therefore believes that specific arguments, such as that based on the logical possibility of zombies, are rooted in this general claim concerning the lack of a structural-
Physical theories are ultimately specified in terms of structure and dynamics: they are cast in terms of basic physical structures, and principles specifying how these structures change over time. Structure and dynamics at a low level can combine in all sort of interesting ways to explain the structure and function of high-
(b) Three ideas linked to structure: causality, epistemic access, and ineffability
It will be important to consider with some care Chalmers' reasons for holding that consciousness lacks the structural content that might enable us to establish supervenience on the physical facts. First, however, I want to look at how the lack of structure of phenomenal experience is linked to a number of related ideas.
Causality: In The Conscious Mind Chalmers discusses the way in which the notion of causality is related to his arguments against materialism: 'Phenomenal states, unlike psychological states, are not defined by the causal roles that they play. It follows that explaining how some causal role is played is not sufficient to explain consciousness' (Chalmers 1996, p. 47, my emphasis). Chalmers also suggests that causation is central to so many of our concepts because we generally refer to what we know about and these are things we are causally connected to. In the case of consciousness, however, we can refer to something that the centre is immediately acquainted with and it is therefore not necessary to pick out something that the centre is causally connected to (Chalmers 1996, p. 202). So Chalmers is saying that when we observe physical entities, we are observing objects that we define by their causal relationships; that we can therefore use conceptual analysis to get down to a more fundamental level of description which is then governed by 'brute' physical laws; but that phenomenal experience does not consist of structure and dynamics, and so is not defined by its causal relationships, and hence is not reducible in this manner.
The type of metaphysics that I described in An Alternative Metaphor suggests an explanation as to why phenomenal states are not defined by their causal role. We assign causal roles so as to give meaning to what we perceive as the physical world, and the objects that we perceive in that world are effectively constructs that originate with the co-
... what justifies us in basing the identification of water with H20 on the causal responsibility of H20 for the typical behavior of water is the fact that our very concept of water is of a substance that plays such-
Epistemic access: Sometimes, Chalmers takes a slightly different approach:
... we saw that ... given the nature of our access to external phenomena, we should expect a materialist account of any such phenomena to succeed. Our knowledge of these phenomena is physically mediated ... . Given the causal closure of the physical, we should expect phenomena that we observe by these means to be logically supervenient on the physical -
I would expand on this by saying that, ultimately, the only access we have to external objects is phenomenal. For us to perceive the physical world as such, we have to objectify it through its causal relationships and structure. However the phenomenal experience is not an objectified entity, it is just there, and therefore is without structure or implied causal relationships. So epistemic access considerations appear to be the underlying reason for the lack of causality and structure in phenomenal experiences. This seems to reflect Chalmers' contention (2003a) that the several individual arguments against materialism have a common form, namely that they establish a form of epistemic gap between the phenomenal and the physical, whether such a gap be in terms of knowing, or conceiving, or explaining the facts about the two domains.
Ineffability: A related quality of our phenomenal experience is that it is ineffable. In fact, one of Chalmers' arguments against materialism depends directly on the incommunicable nature of that experience; this is his argument from analysis -
Chalmers (1996, pp. 290-
Why, under the assumption of functional identity, might qualia be ineffable? ... The subject, since it consists of an ongoing stream of neurally instantiated experience, is not in a position to witness or observe the basic elements of that experience. We cannot, as it were, step back from and describe a quale as we might an external object; thus we can do no more than name basic qualitative experiences ('red,' 'hot,' 'sweet,' etc.) and compare and contrast them to one another. We can't describe the redness of red or painfulness of pain precisely because we can't get a perspective on these qualities.
These considerations relating to causality, epistemic access, and ineffability suggest that phenomenal experience is just as we might expect it to be if we understand it an activity belonging to organisms that have emerged out of a complex universe in the manner envisioned by the likes of Brian Cantwell Smith, Maturana, Pattee, and Humphrey. One might therefore view these considerations as an 'explanation of the explanatory gap', except that I believe that thinking about the debate in this way obscures a number of issues, as I now hope to show.
(c) 'Direct Phenomenal Experience'
Let's turn to what Chalmers himself says about why one cannot analyze phenomenal facts in structural terms. He says (1999b) '... if I were to rest on any point as supporting the central burden, it might be ... the conceptual distance (at least in a priori space) between functional and phenomenal concepts.' My interpretation of the underlying problem as Chalmers sees it is this. In order to move from a description of the physical world to a description of my phenomenal experience, I need some type of concept that links the two, what Chalmers (2003a) refers to as a 'conceptual hook'. But because of the direct and ineffable nature of phenomenal experience, no such conceptual link is available. (Note that this argument clearly has to expressed in terms of concepts, given that we are discussing descriptions of physical facts and of phenomenal experience.)
Chalmers expands on the direct and ineffable nature of phenomenal experience in a recent article (2003b). He carefully distinguishes what he terms a pure phenomenal concept from relational concepts such as a community relational concept ('the phenomenal quality typically caused in normal subjects within my community by paradigmatic red things') and an individual relational concept ('the phenomenal quality typically caused in me by paradigmatic red things'). Supporting the notion of a 'pure' phenomenal concept, he says: 'The property that is referred to need not be relational, however. The phenomenal concept plausibly designates an intrinsic property rigidly, so that there are counterfactual worlds in which red experiences are never caused by red things.' So a non-
This means that Chalmers (2003b) considers that it is entirely possible for two people to be physically and functionally identical (including their history and environment) and yet for one, say 'Mary', to have a phenomenal experience of red when she sees a red object, and the other person, say 'Inverted Mary', to have a phenomenal experience of green when she sees a red object. But this is surely debatable, as the following considerations show:
1. Consider Mary in Jackson's thought experiment that I referred to earlier. Mary's new knowledge, concerning the phenomenal experience of seeing red, relates to a phenomenal concept that is supposedly 'pure' in the sense that it cannot be confused with the relational concept ('the phenomenal quality typically caused in me by paradigmatic red things'), since Mary hasn't had such an experience before. But this distinction doesn't show that there is a definitive 'phenomenal quality of red' that is different from a 'phenomenal quality of green' that Mary might conceivably have had instead. Mary looks at, say, a flower and sees a colour which she doesn't recognize. It isn't black and it isn't white, nor is it 'no colour' (whatever that may mean). She knows that the flower is supposed to be red (maybe she's measured the wavelength of the light before she's seen the flower.) 'Oh', says Mary, 'that's what it's like to see red!' And because of the way her brain works, every time she looks at a red object she will be able to report 'Yes, that's a red object, it's the same colour that I first saw when I looked at that flower.' But this doesn't mean that there was a matter of fact as to which colour she had an experience of, if we understand this as a fact which is independent of the colour of the object that she saw and of the entire situation in which she observed it.5
2. Chalmers also makes the following claim concerning Mary and Inverted Mary:
When Mary leaves the monochromatic room and acquires the confident belief (under her pure phenomenal concept) that tomatoes cause red experiences, she is thereby in a position to rule out the epistemic possibility that tomatoes cause experiences with quality ['green']. The only epistemic possibilities compatible with her belief are those in which tomatoes cause ['red'] experiences. For Inverted Mary, things are reversed: the only epistemic possibilities compatible with her belief are those in which tomatoes cause ['green'] experiences. So their epistemic contents are quite different (2003b, my emphasis)
But this can only be true if Mary is not like Inverted Mary, and on my understanding of Chalmers' position she cannot possibly know this! In fact it is impossible for Mary to know what it is like to see 'red' (defined as the quality instantiated by the pure phenomenal concept), because on Chalmers account she simply has no way of knowing which phenomenal quality she is having the experience of. So what does she now know that she didn't before? Well she knows 'what it is like for me [Mary] to see red', and this knowledge claim surely has to refer to the individual relational concept ('the phenomenal quality typically caused in me by paradigmatic red things'). After all, she can know this if she has, for example, already undertaken experiments to establish that the object that she now sees emits light of the right wavelength, etc. for it to be termed a red object.
3. There is a strange sense in which Chalmers (1996, pp. 268-
What is common to all three of the above examples is the feeling that in one way or another Chalmers ends up divorcing phenomenal facts or phenomenal knowledge from 'how things seem to me'. Aside from appearing to be inconsistent with his stated methodological principle of concentrating on our actual experiences, it suggests that he is hypostatizing our experiential activity as something that is 'its own essence', something that has lost its relationship with our actual, lived existence. Once the hypostatization is available it can just hang there, separated from any other facts concerning the world, and hence can be considered by Chalmers to be an intrinsic, non-
5 The Nature of Explanation
But in what way might we provide an alternative characterization of how our phenomenal experiences relate to the other concepts (including psychological concepts) that we have concerning our mental activities? Perhaps we can say that an individual phenomenal experience exemplifies certain of my other concepts, such as my psychological and functional concepts. And if it exemplifies some of those concepts and it is my own experience, I don't need anything else to hook it up to those other concepts. As I argued earlier, many of those other concepts are themselves derived from my specific phenomenal experiences; my understanding of functional or psychological concepts such as 'attending' are dependent on my own experiences of performing those sorts of actions, which in turn have direct content (at bottom, I just know that I am 'attending'). I may have subsequently developed a more complex concept of 'attending' but its roots lie in my direct phenomenal experiences. So all I need to do is explicitly recognize that some of my experiences exemplify my objective functional concepts.
I believe that this sort of account is consistent with Chalmers' characterization of the nature of a priori reasoning. Significantly, he does not think that there needs to be a logical deduction of the higher level facts from the lower level set of facts. The clearest account he provides is in Chalmers & Jackson 2001. Here he is concerned to counter an argument by Block and Stalnaker to the effect that there is no a priori entailment from the basic facts of physics to facts about, e.g., water and life, but that nobody believes that these latter facts are not reductively explainable, and that, by analogy, Chalmers has no good argument against phenomenal facts being reductively explainable. Against this, Chalmers and Jackson argue that it is possible to conclude a priori that one set of facts implies another without having an explicit analysis of the relevant concepts by which those facts are expressed. They provide an example that uses the concept of 'knowledge' -
When given sufficient information about a hypothetical scenario, subjects are frequently in a position to identify the extension of a given concept, on reflection, under the hypothesis that the scenario in question obtains. Analysis of a concept proceeds at least in part through consideration of a concept's extension within hypothetical scenarios, and noting regularities that emerge. This sort of analysis can reveal that certain features of the world are highly relevant to determining the extension of a concept, and that other features are irrelevant (Chalmers & Jackson 2001).
Chalmers and Jackson stress the importance of the fact that our low level physical knowledge is essentially about structure and dynamics. This allows us to derive a priori conclusions about structure and dynamics at higher physical levels, and this knowledge, together with the an understanding of the relevant concepts, enables us to generate further a priori knowledge concerning higher levels more generally:
For example, knowledge of the appearance, behavior, and composition of a certain body of matter in one's environment, along with complete knowledge of the appearance, behavior, and composition of other bodies of matter in the environment, and knowledge of their relationships to oneself, puts one in a position to know (on rational reflection) whether or not the original system is a body of water. The same goes for knowledge of whether or not the system is gold, whether or not it is alive, whether or not it boils at a certain temperature, or whether or not it is found in the oceans (Chalmers & Jackson 2001).
There are two points to note here. Firstly, on Chalmers' conception of reductive explanation, there is no need for bridge principles that enable the theories and entities at one level to be expressed in terms of theories and entities at another level. All one needs is the lower level physical facts, an understanding of the relevant concepts at each level, and rational reflection. Secondly, ontological knowledge at the higher levels is assumed. One must understand what a cloud is in order to arrive at meteorological knowledge on the basis of lower level physical facts. And of course an understanding of what something is, is essentially a knowledge of what it does, so one can see why a knowledge of structure and dynamics at lower levels can produce knowledge about entities at higher levels.
Chalmers and Jackson also make clear that a posteriori knowledge enters into our understanding of the concepts that we use in our reasoning. So our understanding of how we apply the description 'water' is based in part on our a posteriori discoveries about water and how it behaves. This epistemic knowledge about how to apply the term 'water' in a variety of possible situations is part of our understanding of the concept. '[A]priority is a matter of non-
Consider now the account I gave above of how our individual phenomenal experiences relate to our more general, functional concepts of mental activity. If I claim that my own phenomenal experiences exemplify (at what might be termed the microfunctional level) my general psychological concepts such as attention or memory, why can I not have identified this link between the concepts in an a priori manner? After all, Chalmers denies that a priori deduction requires conceptual analysis, and I seem to have arrived at my conclusion by reflecting in a rational manner on my phenomenal experiences (that is, on my concept of them) and on my concepts of the general psychological functions. This accords with Chalmers' definition of a priori, that is 'solely by means of the relevant concepts'.
6) Metaphysical Issues
Guven Guzeldere (1997) has suggested that the most promising direction for understanding the explanatory gap between the physical and phenomenal involves:
rethinking epistemology and conceptual schemes (as opposed to a priori postulation of [a] new ontology) to yield a cross-
Our review of Chalmers' arguments has considered a number of issues that fall within the general area referred to by Guzeldere, and I now want to try and draw out a more complete picture of this type of 'rethinking'.
A possible argument as to why phenomenal facts cannot be logically supervenient on physical facts might be along the following lines: (i) Any description of the external world comes from an observer, and attributes ontological existence according to the conceptual scheme that happens to be relevant for that observer. Therefore a description of a physical state, for example of neurons in a brain, is something that I as an observer attribute to reality for the purposes of doing (in this instance) neuroscience. Even if I go down to the level of basic physics, my decision to do so, and to pick out certain relationships or groups of particles as relevant, is observer dependent. (ii) So a function can ultimately only be recognized from within; without, there is only our attribution of functionality. And there is no view from nowhere that describes the universe 'as it is' in its entirety, that we can rely on to tell us what the external function 'really is'. (iii) Therefore, when I describe a physical situation, there is always the logical possibility that it subserves any function whatsoever. If I make a particular structural description of the state of a set of neurons, it is not certain what phenomenal state the structure is associated with. One such structure may be associated with different phenomenal states in different creatures, or even in the same creature at different times, depending on precisely what the state helps achieve for that organism at that time; and this will depend, inter alia, on the organism's environment and history. And even if I attribute a phenomenal experience on the basis of my past experience as an observer ('it must be seeing the colour blue' rather than 'it is in fact smelling cheese') it is logically possible (however unlikely in reality) that some unknown fact about the universe means that I am wrong.
Having said this, there does seem to be a looser sense in which the phenomenal facts must supervene on the physical facts, even if the latter cannot be said to strictly entail them. After all, environmental and historical facts are included in the supervenience base, which we could in principle extend as much as we like. One could, I suppose, argue that there cannot be a 'view from nowhere' that encompasses all facts, and that it is therefore a logical possibility that a given supervenience base might subserve a different set of phenomenal facts, or even none at all, because of some other facts of which we have of no knowledge. But I'm not sure this is really moot here; and it doesn't seem to be the sort of consideration that might convince someone who thinks otherwise.
Consider some set of phenomenal facts. I think I would accept that, in principle, there has to be a description of the physical facts that would necessitate 'the same phenomenal facts'; i.e. that at some point the phenomenal facts must supervene in some a priori manner on the physical facts, in the sense that there wouldn't appear to be any 'logical space' for the phenomenal facts to differ. One might imagine that we specify something along the following lines: 'suppose there is a possible world in which the physical facts are identical to the actual physical facts in our world, of every possible type for any possible future science, relating to an area centered around the Sun, and extending for 100 light years around it and for the last 10 billion years'. Now I think I would have to say that I can see no logical space for any aspect of the activities of the human creatures in such a possible world to differ from our own, and given that I accept a microfunctional account of consciousness (for the reasons discussed above, and therefore on an a priori basis), I would conclude that the phenomenal experiences of those creatures could not logically differ from our own. And therefore I would reject the argument that I outlined two paragraphs ago, even though it appears, on the face of it, to follow straightforwardly from the account that I have given of an emergent metaphysics.
I believe that a better starting point is the account of the co-
But in order to have the concepts that relate to the physical world, I have to have the phenomenal experience of that world. So we might consider that it would be a mistake to expect phenomenal facts to be reducible to physical facts, on the ground that the dependency goes the other way -
We saw above that Chalmers appears to hypostatize our conscious activities. He takes the direct and ineffable nature of such experiences to imply that they can logically 'float free' of the rest of our mental activities, such as judgments and conceptual thinking. But if we view our conscious experience as an activity, rather than as a hypostatization of that activity, we can see that this is not the case: I can understand that my conscious experience is an activity, and if I consider my experience and my concepts carefully, I can ascertain what sort of activity it is, and hence obtain an understanding of how my own consciousness relates to the world of which I am part.
This version started: October 2004
Last updated: July 2005
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As one sets out to answer the Hard Question ... one can be sure that no practical, finite set of answers will exhaust the richness of effects and potential effects. The subtle individual differences wrought by epigenesis and a thousand chance encounters creates a unique manifold of functional (including dysfunctional) dispositions that outruns any short catalog of effects. These dispositions may be dramatic -
 Jackson (1982) hypothesized a 'super scientist', Mary, who understands everything about the human brain and how it produces, for example, the experience of seeing the colour red. But Mary has been kept in an environment where everything is black and white, and has never actually seen the colour red. Jackson argues that if Mary is released from this environment and sees a red object, then she will obtain new knowledge, namely what it is like to experience seeing the colour red, despite her supposed perfect knowledge about how the brain produces this experience.
 In his discussion of the logical impossibility of zombies, Chalmers utilizes 'two-
 Dennett (1991, pp. 397-
The way things look to [a wearer of 'upside-
 Some may identify a contradiction here. After all, didn't I claim two paragraphs earlier that I couldn't see any logical space for the experiences of creatures in a possible world that is similar to our own world to differ from our experiences. Well, that argument was somewhat ad hominem: it was directed at someone who supposes that the impossibility of a 'view from nowhere' can, by itself, rule out any logical supervenience of phenomenal facts on the physical facts. My counter argument was that, once I understand my experiences as activities in a microfunctional sense (an understanding that I argue is a priori, in Chalmers' sense of the term), it seems that there has to be some theoretically possible description of the world, where I would have to conclude 'No -