1 60 PETER BIERI Stalnaker, R. (1984). Inquiry. Cambridge, MA: MIT Press. Stampe, D. (1984). Towards a causal theory of linguistic representation. Midwest Studies in Philosophy, 2,4243. Taylor, C. (1985). Human Agency and Language: Philosophical Papers 1. Cambridge: Cambridge University Press. Van Gulick, R. (1980). Functionalism, information and content. Nature and System, 2, Van Gulick, R. (1982). Mental representation - a functionalist view. Pacrfic Philosophical Quarterly, 63, Van Gulick, R. (1983). What difference does consciousness make? Philosophical Topics, 17, Wilkes., K. (1984)., 1s consciousness important? British Journal for the Philosophy of Science, 35, Wilkes, K. (1988). -, yishi, duh, um, aild consciousness. ln Marcel & Bisiach Robert Van Gulick What Would Count as Consciousness has again become a hot topic in the philosophy of mind as shown by the recent spate of books about it (Lycan 1987; McGinii 1991; Dennett 1991 ; Flanagan 1992; Searle 1992). Various theories have been put forward, each of which alleges to fully or at least partially explain what consciousness is and liow it fits into Our overall picture oftlie world (Lycan 1987; Rosenthal 1986; Dennett 1991 ; Searle 1992). In contrast, otlier philosophers have argued that coiisciousiiess is systematcally resistant to explanation in one or another important respect (Nagel 1974; Levine 1983; McGinn 1991). Although the dispute between these two cornpeting groups - the optimists and the pessimists - has involved strongly expressed opinions it has also suffered from a fair amount of conf~ision regarding just what is at issue. Before one can decide how good Our prospects are for explaining coiisciousness we need to be clearer about what would count as doing so. In this paper 1 propose to do just that; my aiin is not to resolve the dispute(s), but just to untangle and claris, the various distinct issues which sometimes get run together in the heat of controversy. The question of wliether we can explain or understand consciousness is systematically ainbiguous in three main respects, and to make it more precise we need to be specific about each of the relevant parameters. A. What is the explandum, i.e. what features or aspects of consciousness do we wisli to explain or understand? B. What can go in the explanans? Tliat is, iii what terms or within what conceptual framework (e.g. physical, functional, naturalistic) inust we construct Our explanation? il : C. What relation must liold between the explanadum and the explanans to count as giving a satisfactory expalanatioii?
2 62 ROBERT VAN GULICIC Given these parameters we find that the question of understanding consciousness is not just one question but a large family of interrelated questions, wliicli rnay liave quite different prospects for successful resolution. In what follows 1 will consider some of the main variants, though 1 will not try to be fully compreheiisive nor cover every possible interpretation of the question; there are just too many readings one inight give it. Nonetheless if we can clearly state the leading variants, we will have made a lot of progress in clarifying the dispute. A. The Explananda Let us begin witli the first parameter; what featiires or properties of consciousness are in need of explanation? Al At a minimum we need to explain the difference between conscious mental states and nonconscious or unconscious mental states or processes. In so far as it is possible to have unconscious beliefs, desires, aiid perceptions or engage in the drawing of unconscious inferences, we need to understand how such states or processes differ from others that are of the same type but conscious. Moreover, there may be some mental states that are of types that can never becoine conscious, e.g. the knowledge or 'cognizing' states postulated by a Chomskyean theory of linguistic competence. Such states are alleged to be geniiinely mental (puce Searle 1992) though they are in principle inaccessible to conscious~iess. A coinmon and appealing move is to define the notion of a conscious mental state as a mental state of which we are conscious. For example David Rosenthal (1 986) analyses a conscious mental state (e.g. a conscious desire) as a first order mental state which is accompanied by a secoiid order thouglit to the effect that one is in the first order state (i.e. 1 desire x and liave the simultaneous thouglit that 1 desire x). Tliere are problems with tlie proposed analysis, but for present purpose it should suffice to illustrate the relevant explanandum: the need to distinguish between conscious and unconscious mental states. A2 We must also explain the distinction between conscious and nonconscious or unconscious creatures. You are clearly conscious wliile you are readiiig this page, and 1 was surely conscious when 1 wrote it, but most of us spend a good part of each niglit being unconscious, and soine unfortunate individuals fa11 into comas from wliicli tliey never reemerge as coiiscious. Some nonhuman animals such as mammals and birds strike us as clearly coiiscious creatures, biit abolit others, siicli as snails or honey bees, we feel * WHAT WOULD COUNT AS EXPLAINING? 63 much less certain. But just what are we asking when we ask whether or not fish are ever conscious? Surely not whether they use their sensory organs to perceive tlie world around tliein and respond appropriately. There is no doubt that they do that. Perhaps one could explicate creature consciousness in terms of conscious states as follows: a creature is conscious at a particular tiiiie only if it has at least some conscious mental states at that time, and a type of creature counts among the conscious types only if it is conscious at least some of the time. But this will be problematic if we accept a higher order thought account of states consciousness: counting fish as nonconscious unless they can have thoughts about their own mental states seems to set too high a standard for qualifying as a conscious creature. Nonetlieless the need to find some way to draw the distinction provides another explanandum. In trying to isolate tlie deeply problematic nature of consciousness, pliilosophers often refer to the subjective, qualitative, or phenomenal aspects of conscious experience. Al1 three terms are directed at those features that in Thomas Nagel's phrase make it the case tliat 'there's something that it's like to be' a conscious thing, i.e. something that it's like 'from the inside' or 'for the creature itself (Nage1 1974). Although the three terms are sometimes used interchangeably, they in fact refer to distinct tliough interrelated dimensions of consciousness. Each of the terms is itself ambiguous and open to multiple interpretations, but in each case we can legitiinately isolate a central or core use that picks out a specific feature of consciousness in need of explanation, thus providing us with three more explananda. Qualia and the qualitative nature of conscious experience are often invoked by sceptics about the explanatory value of one or another theory of consciousness, wliicli they charge with failing to provide an adequate account of the raw feels of experience, the redness of experienced red or the experienced taste of a ripe mango; pains do not merely 'signal' or 'represent' the occurrence of bodily liarm: they hurt, and any theory of consciousiiess tliat fails to explain such felt aspects of Our mental life will be incomplete. The alleged explanatory lapse may concern only specific qualia, or the general issue of how there can be any such properties at all. 'Iiiverted qualia' arguments purport to show the former and 'absent qualia' arguments the latter (Block 1978). Thus understanding coiisciousness requires us to understand its qualitative aspect. If there really are qualia, we will have to understand what sorts of things or properties they are; how something can coine to have them; and what makes it the case that a specific mental state involves the specific quale that it does. Even if, following some recent philosophers, we conclude that there are no such things as qualia
3 64 ROBERT VAN GULICK (Dennett 1988; 1991), we will still have to explain why it seems that there are, as well as explaining what - if anything -the qualitative aspect of experieiice does involve and how it fits within our overall understanding of consciousness. A4 The term 'phenomenal' is sometimes used interchangeably with 'qualitative' in talking about conscioiisness; 'the problem of phenomenal properties' becoines just another name for the difficulty we encounter in trying to explain raw feels, the hurtfiilness of pain or the experienced fragrance of a gardenia. This is a legitimate ilse of tlie term, but 1 prefer to reserve 'phenomenal' for a more comprehensive range of features. Current philosophical debate has focused heavily on raw feels, but they are just one aspect of our experienced inner life and thus only part of what we must deal with if we aim to describe the phenomenal structure of experience. In tliis sense the use of 'phenomenal' accords better with its historical use by Kant and later by the phenomenologists. The order and connectedness tliat we fiiid withiii experience, its conceptiial organization, its temporal structure, its emotive toiles and moods, and the fact that Our experience is that of a (more or less) unifed self set over against an objective world are just a few of features other than raw feels that properly fall within the bounds of tlie phenomenal. Al1 will need to be addressed ifwe take the plienomenal aspect as our explanandum. A5 The third meinber of our triad, the term 'subjectivity', also varies in use witli regard to coiisciousness. Some philosophers use it to inean just that experience lias a first person aspect over and above whatever objective or third person properties it inany have. In that sense, it involves little or nothing that is not already captured by 'qualitative' and 'phenomenal'. However, there is a distinctively epistemic use of the term that merits separate and special attention. It is in this sense that some (Nagel 1974; Jackson 1982 and McGinn 1991) have argued that facts about the experiential aspect of consciousness can only be known or even understood by agents who themselves are capable of Iiaving the relevant sorts of experi- ences -a view with a long empiricist pedigree. Such facts, Nagel argiles, are bound up with a particular (type of) point of view, wliere (types of) points of view are individuated on the basis of tlie sorts of qualitative or plienomenal properties that can be experienced by tlie relevant sort of conscious agent. It is in this empathetic sense that humans supposedly can iiot fiilly iinderstand wliat it would be like to be a bat because we are iiicapable of having echolocatory experiences like those had by bats. VJ!?ether or t:7 what extent this is true is controversial, but 'siil~jective' used WHAT WOULD COUNT AS EXPLAINING? 6 5 in this way differs eiiough from botli 'qualitative' and 'plienomenal' to provide a distinct explanandum. A tinal feature of consciousness that we need to address is the extent to wliich the intentional or representational content of our coiiscious mental states is immediately available or accessible to us, a feature that 1 have elsewhere referred to as the semantic transparency of consciousness (Van Gulick 1988a; 1988b). When we have a conscious thought or experience we typically know on the whole what that thought or experience is about, what state affairs it represents. 1 believe it is in large part this feature of our coiiscious mental life that leads Joliri Searle to distinguish between what he calls the intrinsic intentionality of conscious mental states in contrast with tlie inerely metaphoric intentionality he attributes to computers. He treats coiiscious mental states as intrinsically intentional because they have ineaning or content for the person or creature whose states they are. In contrast the computer's states have content only from the perspective of some external interpreter of its actions; their meaning is not to any degree transparent to tlie computer itself - or so at least Searle claims. Though 1 am not inclined to draw the distinction as Searle does, 1 do believe that his notion of intrinsic intentionality and what 1 cal1 semantic transparency are two attempts to get at a real and important property of consciousness that rnust be explained by a comprehensive theory of conscioiisness. B. Tlie Explanans Altliougli tliese six clearly do not exhaust the list of possible explanailda, they do capture the main features of consciousness that have been at issue in the recent philosophic literature. We can thus turn to tlie second parameter and consider various restrictions on what can appear in our explanans. We get quite different interpretations of oiir original question depending on Iiow we liinit the range of terms, concepts or processes that can figure in our explanatioii of consciousness. Tliere are at least five main variaiits. Although they are not miitually exclusive, and iiideed in soine cases clearly overlap, it is worth regarding each of the five as delimiting a distinct if not wholly separate explanatory domain. The first and perhaps most coininon variant involves limitiiig the explanails to the physical or material. The two are not quite the same since the inaterial concerns only the properties of matter and tliere is inore to pliysics tliaii matter and its properties, but in philosophic discussion it is coinmon to use the two iiitercliangeably and 1 will iiot make inucli of the difference. Piit
4 66 ROBERT VAN GULICK pcific if in these terms the problem of consciousness becomes just a spperliaps particularly intractable case of the mina-body problem: 'Can we understand or explain the relevant aspect of consciousness in purely physical or material terms?' As we shall see when we turii to Our tliird parameter this question is itself open to many readings depending on Iiow we unpack the requisite notion of explaiiation. Moreover there are unclarities in the very notioii of the physical itself. Jiist what counts as a physical property or relation? One could treat as physical any property that applies to physical things, but doing so would threaten to trivialize the mind-body problem. For example any form of dual aspect theory or even property dualism that allowed brains to Iiave both mental and physical properties would collapse into physicalism; there would be no way to assert that brains could have properties that were not physical properties. One would still be able to distinguish physicalism from substance dualism, but in so far as we wish to do more than that we need a way to delimit the set of physical properties more narrowly than as tliose that apply to physical or material objects. On the otlier hand if we turn only to the set of properties tliat are explicitly referred to or qiiantified over in current physical theory we face at least two other problems. First there are many properties that we regard as uncontroversially physical that nonetheless fail to find a place in physical theory proper either because they are liigherorder properties of organized physical systems - the properties of being a comea or a magnitude 7.0 earthquake are physical in this sense but neither is invoked by physicists in their theories Thus we need to extend the range of the physical to cover properties that in some way depend upon or are constituted by underlying physical properties, but just what sort of dependence is required is opeil to debate. Ratlier than restricting Our explanans to the physicial we might instead restrict it to functional relations. Functionalism is the general view that mental states and processes can be characterized and explained in fiinctional terms; what makes something an instance of a given mental state type, such as a belief that interest rates will rise or a desire for a Iiot cup of freshly brewed coffee is the functional role it plays within the functionally characterized organization of some person, organism or system. Though functionalism has come under a lot of critical attack it probably still remains the closest thing there is to a mainline view in the contemporary philosophy of mind. lndeed 1 think many of the alleged refutations of functionalism, e.g. tliose based on the social nature of mental categories (Baker 1985), are best interpreted as disputes between rival versions of fiii~ctionalisrn rather than as attacks on the position per se. lt's just more.. ex:.:!~iig :O prese!.t tbeii? as genera! ref~itations of f~inctionalisin. 1 fowever, WHAT WOULD COUNT AS EXPLAINiNG? 67 the very fact that functionalism admits of so many interpretations means that it's far from clear just wliat a commitment to functional explanation involves. It is sometimes said that functional states of a system are to be type-individuated on the basis of their relations to their inputs, their outputs and eacli otlier. But then questions immediately arise about what is to count as an input or ail output and in what terms are they to be specified or characterized, as well as questions about the nature and range of interstate relations to which one may appeal. In a very simple and restrictive formulation, inputs must consist of externally observable stimuli, outputs are restricted to macroscopic behaviors described in some neutral vocabulary (e.g. as physical inovements) and the range of interstate relations includes only basic relations of causation or inhibition among states or groups of states. The fact that many mental states could not be captured within such a narrow framework would not show that they could not be characterized ~ising a more liberal concept of f~inctional role. The same can be said of theories that unpack tlie notion of functional role in terms of Iiighly abstract computational states, whose realization requires only some form of mapping from the computational states to physical states that preserves formal relations of joint realization and succession. In contrast with such highly abstract forms of functionalism, one could alternatively characterize iiiputs, outputs and interstates relations in ways that involve significant limits on the range of physical realizations. As numerous authors have iioted (Kalke 1969; Lycan 1987), the functional-structural division lias no absolute boundaries, and the there is no context-free answer to questions about whether such properties as being a neuron or being a positively selfsustaining neural loop are functional properties or underlying structural properties. They can be classed as either depending upon the particular explanatory project one is engaged in. A siinilar relativism affects the distinction between whnt role a state plays and how it plays that role; it is sometimes said the functional description is concerned with the 'wliat' wliile questions about tlie 'Iiow' are matters about underlying realization or structure. But the what-how distinction collapses as soon as one tries to put any theoretical weight 011 it. One further and important issue is whether or not the notion of function is interpreted teleologically. To say tliat a given state has the teleological role of doing x, is not merely to say that it does x and that by doing so it plays a certain causal role to the operation of the overall system. If one ; states that the teleological function of the three part bovine stomach is to digest cellulose or that the function of the Dolby circuit on a tape player is to reduce hiss, one is saying more than that tliey do those things within the operation of their respective systems. The teleological claim iinplies that in I doiilg so they are doing what they are supposed to be doing. However there is 110 clear consensus about Iiow to unpack that f~irther element. Some take it to concern tlie striictiire's origiii (Wriglit 1974) and Iiow its d3ing x
5 6 8 ROBERT VAN GULICK figu'ed in tlie selection or design process that lead to its present existence (it's because the lineage of ancestral bovine stomach structures aided in digestiiig cellulose tliat they were selected for by evolution). Otliers interpret it as more a matter of how its doing x contributes to the well beiiig orproper operation of the system of which it is a part (Nage1 1976). Given these many readings of 'functional', claims about which aspects of consciousness can be explained in functional terms are highly indeterminate. Thus it's surprising that confident claims are made about features of consciousness not being open to functional explanation. Can one really say that functional explanations are always vulnerable to inverted or absent qiialia objections given the range of possible ways in which one might read 'functional'? 1 think not. B3 A third option would be to restrict our explanans to naturalistic concepts. There lias been a lot of recent pliilosopliic controversy about whether and liow one miglit give a naturalistic account of intentional content - with covariance tlieories, causal theories and functional role theories among the leading contenders. Similar conceriis extend as well to consciousness. However, the conceptual boundaries of the naturalistic are even more obscure tlian those of the physical and the functional. In part naturalism inherits its vagueness from those first two dornains. Physical and functional relations (at least those that don't involve any suspect and unexplained element of teleology) couiit as naturalistic, and in so far as their borders remain unclear the domain of what's naturalstically acceptable in also left uncertain. However, the naturalistic is generally taken to include more than the physical and tlie functional; biological concepts, neurophysiological properties, historical factors, and more or less any concepts used in any of the nonmentalistic natural sciences miglit as naturalistic. Indeed one might ask, 'Wliat if anything is left out?' The intent seems to be on one hand to exclude explicitly mental properties such as intentionality and subjectivity, and tlie other hand to exclude dualistic, supernatural and magical factors or relations. In the last respect tliere is a specifc intent to rule out theories that appeal to unexplained basic corelations between material properties and mental ones. For example, as McGinn (199 1) lias noted, any tlieory asserting that a given neurophysiological property just causes conscious episodes witliout further elaboration would be dismissed as 'niagical', on a par with turning water into wine. But this really moves LIS iiito issues better dealt with later in section C. B4 A foiirth and final option concerns a less radical but still substantial explaiiatory project: tliat of trying to explain consciousness in terins of WI-IAT WOULD COUNT AS EXPLAINTNG? 69 relations among nonconscious mental states. The project is less radical in tliat it allows mentalistic notions, such as belief, desire, perception, and intentionality, to appear witliin its explanans. It is rioiietheless nontrivial since it is not obvious that appeals to nonconscious mental states and their iiiterrelations will suffice to explain conscious inentality; if consciousness is what make the mind-body problem (seem) really intractable then sliowing liow consciousness can be explained in terins of less problematic mental states would be great progress. The two most prominent exarnples of this approach in the recent philosophic literature are Daniel Dennett's (1991) multiple drafts tlieory of consciousness and the various related versions of tlie liigher order thought tlieory of consciousness as charnpioned by David Rosenthal (1 986). In both cases, tlie attempt is made to explain conscioiisness in tenns of intentional states ('judgeinents in Dennett's version and thoughts in Rosentlial's) that have other mental states as tlieir intentional objects. Altliougli such theories are less radical than direct attempts to explain consciousness physically or functionally, tliey have met with lots of spirited criticism (e.g. Shoemaker 1993; Tye 1993). Most critics have questioned whether tlie alleged theories in fact suffice to explain one or another important aspect of consciousness; for example do they adequately explain the qualitative character of conscious experience? However, our present aim is just to get clear about the nature and scope of the explanatory project not its adequacy. Nonetheless there are some probleins even in that regard. In particular it is unclear just which states count as nonconscious. For example does the concept of tliought iinply consciousiiess? If so, it could not be used to define consciousiiess on pain of circularity. Nor are suc11 worries idle. Some philosophers, most notably John Searle (1 992), have argued that genuine intentionality presupposes consciousness. Should Searle be right, the order of explanatory dependence proposed by Dennett and HOT supporters would have to be reversed. C. Relation between Explananda and Explanans Having completed our survey of possible explananda and explanans, we caii turn to tlie third and perhaps most important paremeter of our basic question: Wliat relation must hold between the two in order to count as an explanation of the relevant feature of consciousness? Here again tlie options are diverse and which one seerns rnost appropriate depends in part on which pair from our first two parameters we are trying to combine. A relation that inight be apt for a physical explanation of qualia inight not be riglit for a f~inctional explanation of subjectivity. There are five main relations to consider.
6 70 ROBERT VAN GULICK WHAT WOULD COUNT AS EXPLAINING? The first is logical siifficiency or deductive entailment. The factors cited iii the explanans woiild coiint as adequate only if tliey provided a logically sufficient condition from wliich one could deduce the existence and nature of tlie relevant feature of consciousness. A pliysical explanation of qualia would have to cite physical conditions that entailed tlie occurrence of mental States with specific qualitative characters. Although the deductive reqiiirement may seem to set a rigorous (perhaps too rigoroiis) and precise standard for explanation, it actually shifts inost of tlie difficult issues elsewhere, ont0 the question of what additional assumptions are being used to bridge the psychophysical gap. The problem is that without some bridge principles deducibility is impossible, but with them jt is far too easy unless their range is suitably retricted. If for example one knew tliat a particular brain state or even a particiilar pattern of perceptual stimulation were invariably correlated as a matter of empircial fact with a given state of qualitative consciousness, one could add the true conditional describirig that link to one's explanans. One could then deduce the occurrence of the specific conscioiis state from the occurrence of the brain event or stimulus condition, but it would not seein tliat doing so would suffice as an explanation of the relevant aspect of consciousness. Surely it woiild not satisfy the explanatory demands of those who worry about consciousness and the inind-body problem. The relevant bridge principle provides nothing more than a brute fact correlation, which even if it is true would not satisfy our legitimate desire to iinderstand why the correlation holds. Thus the deducibility standard doesii't really do much to clarifi the issue of what would count as an explaiiation; al1 tlie difficult questions are just transfered to tlie problem of deliiniting the iiature and scope of allowable auxilliary assumptions and bridge principles. C2 Nomic sufficiency offers a second initially attractive alternative that nonetheless succumbs to the same fate as logical sufficiency. One might require that an adequate explanans provide a nomically sufficient condition for the occurrence of a given aspect of consciousness; i.e. the factors cited in the explanans must necessitate the feature of consciousness as a matter of natural law, which is al1 we require in many domains of scientific explanation. The nomic requireinent also guarantees that the factors cited in tlie explanans are more than just empirically correlated with the relevant featiires or consciousness. Despite these advantages, nomic sufficiency is sub-ject to the same basic objection raised against the logical sufficiency standard. The laws that bridge tlie gap from explanans to conscious explanandum might leave too mucli lef3 iinexplained. The unsatisfying element cf brute fact correlation cal1 reoccur at the nomic level. Brute links inay be al1 we expect at the level of basic laws of nature. For example, it may not inake sense to ask why matter gravitationally attracts according to an inverse square law; it jiist does. But laws linking features of coiisciousness with coinplex ~ioiiconscious factors sucli as patterns of neurophysiological activity would 11ot seem appropriate end points of explanation iior candidates for ultimate and basic laws of nature. Tlius tliey would leave our legitimate explanatory expectations unfulfilled. We seein to need explanations tliat provide sorne greater degree of intelligibility, ones tliat perhaps describe some process or mechanism that let us see intuitively why and how the cited factors necessarily produce the relevant aspect of consciousness. Intuitive sufficiency. Thus a tliird way of delirniting the required explanatory relation is to dernand tliat the explanans specify a set of processes or meclianisms that can be seen intuitively to produce or realize whatever feature of consciousness we are aiming to understand. Without such a specification Our explanatory desires will not be satisfied; too rnany questions of how and wliy will be left unanswered. However, once again the details are difficult to spell out; most importantly what is to count as an intuitive process or explanation? One can appeal to examples from other domains that seem to meet tliat standard, such as explaiiiing the room temperature liquidity of water in terins of its molecular structure or its frozen state below O OC in terms of the intramolecular hydrogen bonds that produce ice crystals. But citiiig examples is not tlie same as definiiig intuitiveness, and it is far from clear how are we to generalize from exaniples like those of liquid water and ice to physical or functional explanations of one or another feature of consciousness. Moreover, tlie problem is complicated by the fact that what strikes us as intuitive is highly context sensitive and relative. Familiarity for example is clearly a factor; having encountered a form of explanation many tiines generally enhaiices its intuitive appeal. Field theoretic explanations miglit have seemed odd and less than intuitive a hundred and fifty years ago, but today tliey qualify as paradigms of naturalness. Perhaps al1 we can Say witli regard to intuitiveness is what an American Supreme Court Justice famously said about obscenity, '1 don't kiiow how to define, but 1 know it when 1 see it.' One would surely like more, but at present that may be the best we can do. Those like Colin McGinn (1991) and Joseph Levine (1983) who are sceptical about our ability to explain how conscioiisness depends on physical processes might argue that no defiiiitioii of intuitiveness is needed to make their claims. No matter how it is ultimately defîned, it seems we do not at present have any intuitively compelling explanations of how to bridge tlie psychophysical gap, at least not with regard to the phenomenal and qualitative aspects of consciousness. I3ut tlieir claiin is notjust tliat we doii't
7 72 ROBERT VAN GULICIC have such explanations ilow biit that we will never have any, and that far stronger claim does seem to require something like a definition of intuitiveness. They need to be able to Say what it is that brute fact psychophysical corrrelations or laws don't provide, and why we will never be able to meet that fiirther standard. PI-edictive models. Though some scientific explanations provide nomic and intuitively sufficient conditions for the features they explain, that is certainly not always the case. We accept as legitimate scientific explanations many theories that provide far less. Some are little more than models that allow 11s to describe and predict the dynamic characteristics of the features being explained and their dependence on relevant causal factors. A global climate model may predict how temperatures and air circulations will change in response to various levels of greenhouse gases. And an econometric model may describe how housing construction will Vary witli interest rates or how trade wiii be affected by tariff reductions. Such models if they are accurate provide a great deal of predictive and explanatory power, but no one would suppose they provide fully sufficient nomic conditions for the phenomena they model. An interest rate/ lioiising construction model does not specify a complete set of conditions for the existence of a housing industry. Might one not similarly explain various features of consciousness without supplying sufficient conditions for their existence. If so, then we Iiave a fourth way of explicating the relation between explanails and explanandum, namely tlie factors cited in tlie explandum must provide us with a model of the feature.~ of consciousness we wish to understand that allows zis to predict and periîaps manipulate those.features in practically or pragmatically relevant ways. This sets a coiisiderably lower standard than any of the three prior relations we have considered and it is unlikely to satisfy those who demand a complete and comprehensive explanation of consciousness, but 1 think it is important to include it among Our options since it reflects a notion of explanation that has wide acceptance in other scientific contexts. If some featiire of conscioiisness can be understood in this last sense, then the fact - if it is a fact - that are we unable to provide fully sufficient conditions for it need not mean we are so mucli worse off with respect to consciousness than we are with respect to many other natural phenomena. Let us review then the variants we have listed for each of the three parameters of our original question, 'Can we explain consciousness?' With regard to the explananduin we distinguished six different aspects of consciousness in need of explanation: the conscious-iinconscious distinction for states and for crcatiires, qualia, the phenomenal aspect, subjectivity, and the transpar- WHAT WOULD COUNT AS EXPLAINTNG? 73 ency or intririsic intentionality of conscious mental states. We distinguished four main domains to whicli Our explanans might be restricted: the physical, the functional, tlie naturalistic, and those features of the mental - if there are any - that do not already entail consciousness, such as the intentional (puce Searle 1992). And last we considered four possible standards for the relation tliat must hold between explanans and explanandum: logical sufficiency, nomic sufficiency, intuitive sufficiency, and providing an accurately predictive and pragmatically useful model. If we list these variants in three columns as in Figure 1, we get a menu of possibilities each one constructed by making a choice from each of the three columns. - - A B C Conscious Explananda Domain of Explanans Linking Relation (aspect to be explained) Al Un / conscious BI Physical Cl Logical sufticiency state distinction A2 Non / conscious B2 Functional C2 Nornic siifficiency creature distinction A3 Qualitative aspect B3 Naturalistic C3 Intuitive sufficiency A4 Phenomenal aspect B4 Nonconscious C4 Predictive and pragmental States matically usefiil rnodelling A5 Sub-jectivity -- Figure 1 For example A3, BI, C3 intreprets Our basic question as 'Can we provide an intiiitively sufficient set of physical conditions for the qualitative aspect of consciousness?' or put in a sliglitly different form 'Can we provide an intuitively satisfying explanation of how physical processes give rise to qualitative consciousness?' By contrast the triple of A 1, B3 and C 1 resiilts in the question 'Can we provide logically sufficient coriditions for distinguishing between conscious and nonconscious states solely in terms of intentional and other nonconscious mental states and relations?' Given the options along Our three parameters Our menu generates ninety-six possible interpretations of Our original question. Though some of tliem may not be worth considering, many are. i However, the general strategy of dividing Our original question into a number of more specific ones might be challenged on one of two grounds. First someone might object that the various aspects of consciousness that * we listed under A are in fact inutually interdeperideiit and sliould not be
8 74 ROBERT VAN GULICI< separated nor explained in isolation from one another. Doing so might be criticized as artificially fragmenting a domain that has a deep and natural ~inity. Thougli some of tlie aspects we distiiiguished - e.g. phenomenal organizatioii and qualitative character - may indeed be intimately intercoiinected, those links need to be sliown and themselves explained rather than merely assumed. Thus it seems better to begin by distinguisliing the various aspects conceptually; having done so we can then discover wliat relations or dependencies hold among tliem in tlie course of trying to explain each. If in fact one aspect is found to depend upon another then obviously we won't be able to explain the first withiti a given domaiti utiless we can also explain the second witliin that saine domain; if subjectivity depends on qualitative character then we will not be able to explain it in pliysical or fi~nctional terms unlesswe can do the same for qualia. However, such connections should emerge from oiir explanatory efforts rather tlian be iinposed on them by assumption from the outset. A second objection to Our separation strategy inight be that it leaves soinetliiiig out iti so far as its separate explananda fail to capture al1 that's included in Our original explaiiatory target. Sucli an objectioi-i iniglit be uiipacked in one of two ways: either by noting soine aspect(s) of consciousness not included in our list that require(s) explanation, or by claiining that consciousness per se is something more than just its totality of its aspects -'the whole is more than the sum of its parts'. In tlie first case, the problem cari be easily remedied by adding the allegedly missing aspect to our list of explananda tliereby generating yet further explanatory projects. Indeed 1 never claiined tlie list given under A was comprehensive and there are surely some plausible candidates for inclusion; if for exainple consciousness iiivolves some element of freedoin or creativity that is incompatible witli determiiiism or algorithmic specification as Roger Peiirose (1994) has recently claimed Ilien it too would need to be added to our list. Tlie strategy of articulating our basic question into inore specific inquiries would not be affected. The second form of the objection might present more of a pi-oblem, but it's far from clear what it amounts to; it appeals to a supposed failure to capture an il1 defined and mysterious sometliing which is not itself an aspect of corisciousness, just a sometliing je ne sais quoi. I am reluctant to say that no objection could be raised along such lines, but absent some better formiilation of tlie problem I think we can safely ignore it. If we set aside these objections and follow our basic separation strategy, we will find that oiir present state of progress and our prospects for future success Vary greatly across the different specific questions that get generated. For exainple higher order theories such as those offered by Dennett and Rosenthal seein promising as a means of drawing the logical distinction between conscious and u~iconscious mental states in intentional terms (interpretation Al, B4, C 1.) Such tlieories are not williout tlieir probleins, such as tlie follo~ing. First, as noted above, tliey seein to require us to WHAT WOULD COUNT AS EXPLAINING? attribute sopliisticated liiglier order judgernents to iionhuman nonlanguage-using animals and sinall children. Second defining coiisciousness in terms of higher order thoughts would be unilluminating if the notion of tliought were to turn out to presuppose consciousness. And third there seem to be cases in which the presence of the relevant sort of higher order states fails to confer consciousness on its object. If for example in a Freudian case, a given state - perhaps an illicit desire - is being actively and successfully repressed it seems tliat we would classi& it as an unconscioiis state even though the intentional activity of keeping it repressed seems to require the existence of a higherorder state whose content is that one has that very desire. Noiietheless these inay be just matter of detail that can be handled successfully within the higher-order framework, and such tlieories do seem to capture at least one important sense of 'conscious' as it is applied to mental states in everday use. By contrast the project of showing in intuitively obvious terms how qualia depend upon physical properties or relations seems mucli more dauiiting ifnot impossible. It is sometimes claimed that we don't even know what form such an explanation might take; we just find ourselves staring at a blailk wall with no real idea of how to begin to construct an explanation. Thougli the project is a difficult one, 1 don't believe our situation is quite that bad. As 1 have argued elsewhere (Van Gulick 1993) the first step in bridging tlie gap is to articulate structural organization witliin the qualitative and phenomenal domain. Havirig done so, it is possible to search for corresponding patterns of structure at lower levels of organization that might uiiderlie what we find at the conscious level. Part of the reason we get a blaiik wall feeling wlien we think about physically explaining qualia is tliat the problem is posed as trying to find some explanatory relation between a single isolated qcalitative property, such as the taste of a mango or the redness of my visual experience when 1 look at ripe toinato, and some local physical or neurophysiological property. In so far the qualitative component is presented a sui generis simple property it is hard to see how any relation it might bear to its neurophysiological basis could be anything other than an intuitively unsatisfying brute fact. However, if we are able to articulate structural organization withiti tlie qualitative doinain, then more explanatorily satisfying options are possible. For example the qualitative colour space has an inherent interilal organization (Hardin 1988) defined in part by relations of similarity and composition; some colours are perceived as unary noncomposite colours (red, green, blue and yellow) while others are experienced as binaries or composites (purple, orange, turquoisc, and chartreuse). This purely qualitative organization can be explained in terms of tlie opponent process organization of the neural processes underlying colour perception. Experiences of red result when the redlgreeii channel is higlily active and the yellow/blue cllaiinel is near base rate; conversely we experience orange
9 l l 76 ROBERT VAN GULICIC when there is a high level of activation in both channels. Qualitative binariness can be explained in terms of the double activation of the two iiet~ropliysiological processing chaniiels. The crucial explantory step is recognizing and describing the qualitative organization that needs to be explained; once we Iiave done so the standard scieiitific practice of explaining organization or structure atone level in terms ofcorresponding relations at an underlying level can come into play. It is only when we treat the qualitative or phenomenal explanaiidum as a simple that we confront a blank wall or mere brute fact relations. A second example is presented by the fact that our normal visual perception iiivolves the phenomenal experience of a meaningful world of familiar objects. We do not normally experience a world of inere shapes and colours; what we see are scenes, events and objects of meaningful types. When 1 look at my desk, what 1 see is my computer, my notes, and the afternoon sun dappling the wall behind tliem. Nor is tliis a matter of some distinct interpretative element that accompanies our seeing; it is a phenomenal feature of the visual experience itself. However, in soine pathological cases, this plienomenal organization is lacking or severly disturbed. Patients suffering from associative visual agnosia Iiave nearly normal perception of tlie geometrical features of what they see, but they are unable to connect those visual inputs with tlieir knowlege of tlie world and their scheme for categorizing objects (Farah 1991). Tliougli they know what a stapler is and can naine it immediately if allowed to touch it, they cannot recognize it visually despite the fact that tliey can draw a highly accurate picture of its shape. Given this pattern of deficits we can begin to explain how the plienomenal organization tliat is present in normal cases miglit depend on neurophysiological organization. The brain areas damaged in visual agnosia generally involve tlie cortical regions devoted to the last stages of visually processing (areas V6) and the nearby regions of associative cortex tliat are concerned with iiiterserisory integration. Thus what was true witli respect to the iiiiary/binary distinction in the qualitative here also holds with regard to the phenomenal. Once we have articulated structural organization at tlie conscioiis level we can pursue genuinely explanatory links with underlying patterns of neural organization, tliough adinitedly inuch inore needs to be said about the specific case (Van Gulick 1995a). Nonetheless pessimists or sceptics inight object that such appeals to underlying organization can provide at best incomplete accounts of how the phenomenal and qualitative aspects of consciousness depend upon neural structure and activity. They may explain wliy they have some of the relational structure tliat they do, but they will not explain the qualitative and phenomenal aspects themselves. But just what is supposedly left out and forever heyond the reach of such explantions? The claiin seems to be that we inight capture and explain the relations that hold ainong the plienomenal eleinents but no1 tliose elements themselves; they remain beyorid our WHAT WOULD COUNT AS EXPLAINING? 77 explanatory reacli or so it's claimed. This is an initially plausible claim, but we must be wary not to fall back into tlie trap ofregarding qualia as simples. There is no reason to do so, and good reason not to since it will bring us right back to the blank wali. Nonetheless tliere are two genuine worries raised by the pessimists, thougli neither presents an iiisurmountable problem. First we do need to explain how there can be phenomenal and qualitative properties at all; relational theories tliat took their existence for granted would indeed be far from complete. But the correct response is not to look for some nonrelationai explanation but rather for a relational theory witli the right terms as relata. As noted above, we sliould not try to establish explanatory links between isoiated qualitative properties (the taste of a mango) and local brain events; this only provokes objections like the old pliilosophical standby of asking why C-fibre firings sliould liurt, feel like pain, or indeed feel like anything at all. We need instead to ask how the overall organized activity of a brain can give rise to a conscious self? If there really are such things as qualia - and 1 believe there are - they are properties of objects tliat exist only from the internal perspective of such a conscious self, and such a self can in turn exist only in so far as it is the subject of a stream of experience with the requisite internal phenomenal organization. Both tlie self and tlie qualitatively differentiated objects of which it is aware are entities that emerge out of the organized stream of experience rather than independently existing items that precede experience (Van Gulick 1988b; Dennett 1991). Providing a detailed theory of how this entire relational structure might depend upon neural organization is indeed an enorinous task, but nonetheless one for which tliere is a possiblity of success in tlie long run. The second genuine worry raised by the pessimists is that there is a form of understanding with respect to specific qualia that no third person explanation can provide, namely tliey cannot give us ail empatlietic first person understanding of what it's like to have an experience with that quality unless we are capable of such experiences ourselves. Empathetic understanding can be gained oiily by undergoing the relevant experience through zn act of perception or imagination. This is tlie familiar empiricist point of Thomas Nagel's (1974) claims about our inability to understand what it's like to be a bat and Frank Jackson's (1 982; 1986) example of Mary the super colour scientist who lias never herself experienced red. 1 agree that siinply entertaining a complex physical or functional desription of what goes on in someone's brain when lie or slie experiences red will not provide 11s with a synipathetic understanding of wliat it's like to have red experiences, and thus we would be left lacking some understanding about sucli conscious episodes and qualia. But there is a sense in which a theory of consciousness inight be explanatorily complete even if it is limited iii tliis way. Speaking of a theory that is
10 7 8 ROBERT VAN GULICK both limited but complete may at first sound paradoxical, but there need be no contradiction as along as the explanatory limits are entailed by the theory itself. That is, the theory can be complete in so far as it entails the inevitable existence of certain limits on what we can explain or understand and then provides al1 the explanations that are possible within those limits. Tliis is indeed the position 1 have argued (Van Gulick 1985) we should take in response to Nagel's bat example. Although 1 cannot reproduce the detailed argument here, it can be shown that the existence of such limits is a direct consequence of an independently plausible functionalist theory of understanding. Their existence thus provides further support for that theory and does not in any way impugn its explanatory completeness. Colin McGinn, though a leading pessimist, has himself recently offered his own version of completeness within limits (McGinn 1991). He has tried to show that Our human means of forrning concepts are incapable of providing us with concepts able to bridge the psychophysical gap and thus the the link between consciousness and brain must remain forever cognitively closed to us. He regards his version of naturalistic physicalism as nonetheless complete in so far as the limits on what it can explain follow from the theory itself. His account of self-limiting completeness differs from my own in two major respects. First he is much more pessimistic and places far greater limits on what we can hope to explain; he places the psychophysical link in its entirety beyond human understanding while my own theory only limits us from understanding alien forms of experience in al1 the ways that are possible from the first person perspective. There are many aspects of the psychophysical link that we can hope to understand in a fully satisfying way. Secondly, his argument relies iipon strong assumptions about the limits of hiiman coricept formation that are not very plausible whereas the limits in my own inodel follow from some very general functionalist principles about the pragmatic nature of understanding. 1 do not have adequate space here to present a full defence of my own theory or a detailed criticism of McGinn's. My present aim is just to make clear how one might have a theory of consciousness that was both explanatorily selflimited but complete, as well as to indicate that there are a variety of ways of formulating suc11 theories. That much I hope to have done. Indeed my overall intent in this paper has not been to offer or argue for any given explanation of consciousness. My goal has been more modest: just to clarify the nature of Our initial question and articiilate its many possible interpretations and their interconnections. 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