Philosopher Christopher Norris, whose book Epistemology is discussed here on Ichthus77, has granted me permission to post the following as a guest post and enter it into the most recent Philosophers’ Carnival. It was written a couple weeks back and is under consideration for a regular print journal, so until then I am honored to display it here. Thankyou, Professor Norris :)
Outside the Box: on the ‘extended mind’ hypothesis
In this essay I examine various aspects of the ‘extended mind’ (EM) thesis proposed by David Chalmers and Andy Clark. Their claim is that various items of extra-cranial equipment (ranging from notebooks to iPhones) are so closely bound up with the mental processes of those who use them that they must – on a ‘parity principle’ – count as parts or integral components of the users’ minds. Opponents of the thesis typically object that minds don’t have parts, that the devices in question are themselves products of human ingenuity, and that intentionality – the mark of the mental – cannot be attributed to notebooks or iPhones without falling into gross confusion. In response the advocates of ‘strong’ EM run a range of arguments, mostly of the slippery-slope kind, in order to press their point that there is no way to draw a firm or principled line between ‘internal’ and ‘extraneous’ modes of mental extension or cognitive enhancement.
My essay reviews the current debate, starting out from a position of broad sympathy with the EM thesis but then raising problems with it from a phenomenological as well as ethical and socio-political standpoint. I conclude that its advocates have been too much concerned with prosthetic devices of a physical or material kind and have thereby been led to under-estimate the role of human inter-personal, collective, and social exchange as a source of expanded mental powers. By way of pointing up this missing dimension of the EM argument I briefly trace a history of thought – from Spinoza to Negri and other recent theorists – which lays chief stress on the idea of ‘multitude’ as a means of breaking with the entrenched individualism of Western post-Cartesian philosophic thought.
Keywords: brain, cognitive science, epistemology, extended mind, externalism, mind, phenomenology, psychology
Consider, if you will, the sheer variety of (supposedly) non-mental since extra-cranial processes and events that have gone into the making of this article. I am writing it with the aid – more than that: with what feels like the active involvement – of a computer/word-processor linked to the internet and sometimes providing me with prompts, references, links to relevant online debates, and so forth. Besides, what I write even during periods of off-line dedication to ‘the writing itself’ is inevitably shot through with a great many witting or unwitting allusions to my online reading and is also, crucially, shaped in large measure by this experience of thinking and working in tandem with a whole range of modern technologies. Indeed their influence goes far deeper than their role in merely providing us with more convenient, speedy, or well-stocked and ready-to-hand informational resources. Rather it reaches into various regions of our cognitive, intellectual, and even our affective lives in such a way as to induce a profound re-structuring of knowledge and experience alike.
To think of those technologies as extra-mental – as standing in a merely prosthetic or supplementary relation to the human mind – must in that case be a big mistake and a product of the anthropocentric or human, all-human tendency to draw a categorical line between what transpires inside and outside the skull. Once rid of that prejudice, so the argument goes, we can start getting used to this counter-intuitive yet strictly inescapable truth, namely that the mind is not intra-cranial but engaged in a constant two-way traffic with objects, events, and information-sources beyond the individual brain. Moreover this is an active reciprocity – a mutual exchange or feedback-loop with continual adjustment on both sides – that finds no place on more traditional (not just Cartesian) conceptions of the mind-world relationship. Quite simply, philosophers have got it wrong and shown themselves prey to mistaken, folk-psychological beliefs by adopting the view, in however philosophically ‘sophisticated’ a form, that mental processes and events must be thought of as transpiring in a realm quite apart from the various ‘external’ devices whereby human beings often contrive to enhance their cognitive powers. Thus the various IT resources that I have called upon in writing this essay – or throughout its period of intellectual gestation – are not just so many useful aids or handy adjuncts to processes of thought that would otherwise have gone on largely unaffected by their absence except for some limiting conditions with regard to information access and ease of textual or data processing. Rather they have become so intimately a part of the cognitive process itself – so deeply bound up with every stage in the business of data-retrieval and selection, ideational synthesis, concept-formation, inference, analogy, critical review, and so forth – that it is no longer possible to draw any clear or principled line between mental and non-mental or intra- and extra-cranial events. More precisely: any such line-drawing will amount to no more than a stipulative fiat or a last-ditch attempt to conserve some privileged space for the human (i.e., what is conceived as uniquely or distinctively human) against the perceived encroachments of modern techno-science.
Such is the ‘extended mind’ (henceforth ‘EM’) hypothesis advanced by a number of vigorous and eloquent present-day advocates, chief among them David Chalmers and Andy Clark. It was their jointly authored essay of 1998 that first set out the hypothesis in its full-strength boundary-shifting form and very quickly produced a wide range of responses for and against. Most prominent among the nay-sayers were philosophers of mind and cognitive psychologists, like Jerry Fodor, whose disagreement turned on what they diagnosed as the basic error – or category-mistake – necessarily involved in any ascription of mental states, contents, capacities or powers to extra-cranial (and hence, by definition, non-mental) items. For Fodor it is a truth borne out by commonsense judgement and philosophical reflection alike that mental content is ‘underived’, that is to say, sui generis, non-dependent, and in itself the sole possible source of whatever strictly derivative contents might attach to various kinds of supplementary device. What sense can there be, he asks, in talking about minds as if they had parts – additional parts or the scope for such piecemeal augmentation – so that some of them (maybe through possession of an iPhone) might come to have more parts than others? Is it not the case that our recourse to – even, at times, our reliance on – devices of this sort requires both that they have already been programmed (by ourselves or others) with relevant, reliably sourced information and also that we, the end-users, should believe that information or at any rate take mental note of it. For Fodor, in short, ‘externalism needs internalism, but not vice versa [since] external representation is a sideshow; internal representation is ineliminably the main event’. In this respect he stands foursquare with other thinkers, among them John Searle, who likewise regard underived content – or intentionality – as the distinguishing mark of the mental.
Clearly this also sets him squarely opposed to advocates of the EM hypothesis. Their point is to challenge all such ideas of a mental domain whose locus, however problematically, is inside the human skull. On their account the predicate ‘mental’ stands in need of radical semantic surgery so as to extend its range of application not only beyond the ghost-in-the-machine of Cartesian mind/body dualism but also beyond the individual brain as it figures in the discourse of hard-line eliminativists or central-state materialists. Indeed this proposal goes even further in an anti-mentalist or anti-Cartesian direction than the thoroughly integrated nexus or synthesis of mind/body that we are urged to endorse – albeit for very different reasons – by continental phenomenologists and analytic strong-naturalists alike. Chalmers and Clark seek to persuade us that a great many items commonly thought of as extraneous to mind-brain are in fact so deeply intertwined with our perceptual, cognitive, intellectual, affective, and creative or imaginative experience as to constitute not merely prosthetic devices but integral components thereof. Just as mind reaches out into world through various kinds of applied technology – from the humble notepad and pencil to the iPhone or other such hi-tech marvels – so world reaches deep into mind through the active combination of that same technology with the human aptitude for adjusting to new and sometimes transformative changes in its ambient life-world. Hence the Chalmers/Clark ‘Parity Principle’, according to which: ‘[i]f, as we confront some task, a part of the world functions as a process which, if it were done in the head, we would have no hesitation in recognizing as part of the cognitive process, then that part of the world is . . . part of the cognitive’. I would guess that the untypical clunkiness of this crucial sentence has its point in stressing both the knotty imbrication of mind and world and the resistance that this claim tends to generate in many – Fodor among them – by reason of its coming so sharply into conflict with a range of deep-laid intuitive beliefs.
In his book Supersizing the Mind Clark offers numerous striking examples of past, present and future-possible developments which he considers to present a powerful challenge to defenders of the inner/outer dichotomy or suchlike (as he sees them) Cartesian residues. On his account it is not enough for those of an expressly anti-Cartesian persuasion – mind/brain identity theorists or exponents of a thoroughly naturalised epistemology and philosophy of mind – to reject the charge outright. Where they still betray signs of that bad old heritage is in stopping short at an intra-bodily or ‘skin-sack’ monism which might indeed count as radical in terms of received philosophical wisdom but fails to question the other, more tenacious dualism. That is, they persist in trying to demarcate mental (even if physically embodied) processes from non-mental since extra-bodily means of cognitive enhancement. Clark’s book is largely devoted to running a series of slippery-slope arguments – some of them involving extant technologies, others more in the nature of thought-experiments – designed to show just how questionable, or downright arbitrary, that line really is. Thus his point is to provide a whole series of ‘intuition-pumps’ (in Daniel Dennett’s useful phrase) so as to wean us off accustomed ways of thought, whether philosophical or folk-psychological, according to which there just must be a difference – a humanly salient or crucial difference – between what goes on inside and outside our skulls.
It is important for Clark’s argumentative purposes that this claim should extend well back into the history of cognitive enhancement techniques. Thus he makes a strong point of invoking ‘primitive’ techniques such as pen-and-paper or the sundry mnemonic devices that people have used, down through the ages, to supplement their limited resources of ‘internal’ memory or their restricted capacity for processes of ‘purely’ mental computation. (I am making this liberal use of scare-quotes, let me say, in keeping with the anti-dualist conviction that motivates the EM hypothesis, since for now I am trying to represent their case without prejudice either way.) If one thing is intrinsic to the human mind it is not the kind of delusive self-sufficiency envisaged by Descartes and his legion descendents – some of them unwitting or deeply in denial – but rather this capacity for linking up with its environment in adapative, creative, and self-transformative ways. This why Clark likes to offer a range of homely examples so as not to be accused of resting his case too heavily on the latest in current technology or on speculative glimpses of a higher-tech future like that which might be opened up by ‘cyberpunk’ silicon brain implants.
Hence his best-known fictive or thought-experimental case-study, that of Otto and Inga the two art-loving New Yorkers who decide to visit the Museum of Modern Art on 53rd Street. While Inga relies on her memory to get there – on resources ‘internal’ to her own mind or brain with its range of unaided mnemonic powers – Otto is suffering from a mild degree of Alzheimer’s disease, and must therefore consult the directions written down in his notebook. Clark’s point is that there is no rational or principled, as opposed to adhoc or arbitrary, way of drawing a line between the two kinds of memory and the two sorts of procedure for getting from A to B. Of course the mentalist/dualist/internalist will raise all the obvious objections, such as the (presumptive) fact that Inga has direct access to her memories as opposed to Otto’s indirect access via his notebook, or that Otto has to inspect its content whereas Inga just knows – without need for any such roundabout means – how to reach MOMA by the quickest route. However Clark is breezily unimpressed by these and other counter-arguments put up by critics of the EM hypothesis. Where they always beg the question, he claims, is by taking for granted the validity of certain deep-laid yet far from self-evident folk-psychological beliefs.
Still this has failed to convince those who see nothing naively folkish about the idea that there exists a real (and not merely adhoc or gerrymandered) boundary between whatever goes on in our heads and whatever goes on in the world outside our heads. Thus Fodor fires number of sceptical ripostes back at Clark, among them the suggestion that he try this vignette: Inga asks Otto where the museum is; Otto consults his notebook and tells her. The notebook is thus part of an ‘external circuit’ that is part of Otto’s mind; and Otto’s mind (including the notebook) is part of an external circuit that is part of Inga’s mind. Now ‘part of’ is transitive: if A is part of B, and B is part of C, then A is part of C.
In which case, Fodor continues, ‘it looks as though the notebook that’s part of Otto’s mind is also part of Inga’s’, with the consequence that ‘if Otto loses his notebook, Inga loses part of her mind’. This sounds logical enough and would seem to knock a hole in the EM case were it not for the temporal aspect of the story which allows both circuits (Otto’s with his notebook; Otto’s mind with Inga’s) to be broken once Otto has mislaid that precious item. After all, it is quite explicitly a question in Fodor’s narrative of who knows what and when, that is to say, of knowledge acquired by both parties at a certain stage in the proceedings and then lost by one of them (due to his memory deficit) but presumably not by the other (due to her suffering under no such disadvantage). However Clark ignores this point and focuses instead on what he takes to be Fodor’s most substantive objection, namely his above-mentioned argument concerning the ‘underived’ (self-sufficient or autonomous) nature of mental content as opposed to the ‘derived’ (dependent or second-order) status of physical prostheses such as Otto’s notebook. His rejoinders regularly take the form of turning Fodor’s objections around so as to argue that any sense in which Otto’s knowledge or cognitive state can rightfully be called ‘derivative’, ‘secondary’, ‘dependent’, ‘unreliable’, ‘indirect’, ‘error-prone’, ‘fallible’, or whatever, is also – at no great stretch of counterfactual reasoning – a sense that applies equally in Inga’s case.
According to Clark, ‘both modes of storage can be seen as supporting dispositional beliefs’ – Inga’s self-accessed data bank no less than Otto’s ‘external’ guide – since Inga also needs to consult her memory, as the phrase goes, and retrieve the relevant items of information for the purpose at hand. Moreover she has to have confidence in their accuracy and reliability even if that belief is so much a matter of unthinking routine commitment as scarcely to register at the level of conscious or deliberative thought. Thus Inga’s reliance on ‘unaided’ memory is not, after all, sufficient to establish a categorical or even a reasonably clear-cut distinction between her way of getting to MOMA and Otto’s reliance on his trusty aide-memoire. The latter is indispensably a part of that single integrated system that makes up Otto the absent-minded though cognitively enhanced way-finder, just as Inga’s memory functions as part of a complex system including – as a formative part of its background history – the possibility of error bound up with all recourse to the presumed self-evidence of first-person recollection. Besides, again contra Fodor, Otto’s habit of relying on his notebook is one that we should think of as having acquired the force of habit – of ‘second nature’ – and therefore as being so tightly bound up with his needs, desires, feelings, thoughts, purposes, and intentions as to constitute a quasi-automatic response fully on a par with Inga’s implicit dependence on memories laid down in her brain. And to Fodor’s objection that Otto has to make an extra effort, i.e., that of consulting his written directions Clark responds that the business of remembering – of calling things to memory – can be quite arduous and by no means always so straightforward and uncomplicated as tends to be suggested by talk of ‘underived’ (mental) as opposed to ‘derived’ (artificial or prosthetic) content.
Thus ‘[i]f one denies a dispositional belief to Otto on the grounds that he has to consult his notebook, then one should also deny a dispositional belief to a version of Inga who has to wilfully consult her memory’. One has to assume that Chalmers includes the word ‘wilfully’ not by way of conceding that Inga’s and Otto’s situations are different when her memory is functioning normally, quickly, or spontaneously but rather as a first stage in getting his opponents to see that in fact the same applies in that case too. After all, it is the habitual or well-nigh ‘automatic’ character of Otto’s mnemonic practice – the fact that it forms so seamless a part of his getting around town – that qualifies the notebook as an integral component of his mental life and not a mere supplement or add-on. Here again the crucial point is that the ‘coupling’ between man and device be so close, regular, reliable and habitual as to constitute a genuine circuit or feedback-loop rather than an adhoc or every-so-often and hence less dependable resource. In such cases, according to Chalmers and Clark, there is no relevant sense in which the domain of mental processes and events can be thought to exclude those various ‘external’ items that enable the mind/brain to function more efficiently. It may yet be objected that inert items such as notebooks or notebook-entries, unlike brains, have meaning, purpose, or intentionality only through some prior investment of ‘underived’ mental content, that is, through the directions having been written down – whether by Otto himself or by a helper – with the aim of getting him to MOMA. However they respond once again that this objection misses the mark since it fails to grasp that the writing-down is just as much a product of that same ubiquitous interaction between brain, world and the various basic or advanced technologies that play a more or less prominent role in the commerce between them.
Another staple of debate is the use of slippery-slope arguments, most often deployed by upholders of the EM hypothesis against those who defend a mentalist or ‘intra-cranialist’ position. The idea is that Fodorians will always be vulnerable to this type of reasoning since they are trying to fix a line of demarcation where no such line can justifiably be fixed, in which case there will always be a ready supply of marginal, borderline, or (for them) problematical instances. What if Otto’s notebook were replaced by a silicon brain implant programmed with the details of his best route to MOMA, along with any amount of other information as and when required? Or again, what if the device had wireless access to a data-bank reliably and regularly primed with just the sorts of details that enable Otto to find his way around and generally manage his life? And what if that provision were further enhanced at some future yet presently conceivable stage of advance by a highly sophisticated feedback system whereby to detect and respond to Otto’s informational needs through its capacity to ‘read his mind’, i.e., pick up and suitably interpret certain recognisable kinds of neural activity? Such scenarios are thought to create a large problem for internalism since they force the question of exactly where – at what point on the scale of deepening physical as well as psycho-cognitive integration with Otto’s lifeworld – the device in question might properly count as a fully-fledged extension of his mind. Clark’s wager is that the internalists will be stuck for an answer, or at least for any answer that doesn’t beg the question against the EM hypothesis. They will either resort to some shifty fallback position with distinct though disavowed Cartesian implications or else bite the bullet, deny that slippery-slope arguments of this sort possess any genuine force, and continue to maintain – as Fodor does – that underived content is the mark of the mental and that minds just ain’t outside the head.
This seems to me a striking example – one of many to be found in philosophy, perhaps for reasons endemic to that discipline – of a debate carried on with great intelligence, wit, and resourcefulness by both parties and yet without reasonable hope of a decisive outcome or, to adapt Dr. Johnson’s mordant phrase, a conclusion in which something is concluded. Thus it exemplifies the way in which advocates of two flatly opposed positions can each bring up a range of strong and, on their own terms, convincing arguments while curiously failing to engage each other except at a level where every last move in the debate seems to be programmed in advance. Of course it might be said that this is only to be expected since, after all, the quarrel between EM-advocates and intra-cranialists is just another version – a techno-savvy update – of old controversies like those around Cartesian dualism or, what is usually somewhere in the offing, free-will versus determinism. Hence no doubt the depth of commitment on both sides but also, perhaps in consequence of that, the lack of any real prospect that either party will achieve some decisive advantage or come up with some knockdown rejoinder. Chalmers and Clark have no end of slippery-slope instances by which, as they think, to create new problems for the internalist while s/he in turn has arguments in plenty (usually involving an appeal to some aspect or analogue of intentionality) whereby, as s/he thinks, to refute the proponents of strong EM. The latter then respond that Fodor and his allies are merely betraying their residual Cartesianism by attaching such an undue weight of significance to the (supposedly) issue-settling witness of conscious, reflective, or deliberative thought.
Slippery-slope instances include the use of fingers for counting or multiplication vis-à-vis the use of electronic calculators; the Filofax vis-à-vis the iPhone; diagrams and tables of various kinds; the popular (if old-fashioned) image of the engineer always with a slide-rule attached to his [sic] belt; the scrabble player shifting letters around in an offline trial of word-constructing possibilities; and any number of kindred cases where an ‘old’ appliance finds its equivalent – at whatever technologically geared-up remove – in some present-day invention. Also very apt to their purpose is the computer game Tetris where players have to rapidly perceive various objects of this or that geometric shape as they descend from the top of the screen and build a wall at the bottom by intercepting and rotating them so as to fit the available slots or sockets. Here the slippery-slope runs: (1) the game-player does all this ‘in her head’, i.e., by rotating the shapes in her mind’s eye and relying on her unaided sense of visual-spatial orientation; she can either choose to proceed as in (1) or else press a button to rotate the objects on screen (with some advantage in terms of speed); and (3), looking forward to a plausibly not-so-far-off future, the player has been fitted with a brain implant – a silicon-based neural chip – which allows her to perform the action just as quickly as did the computer in situation (2) but without pressing the button since now the operation is carried out through an act of the conjoint mind/brain along with its integral (or ‘internally’ hard-wired) shape-shifting device. Clark and Chalmers present this particular case with very little in the way of commentary or analysis, clearly regarding it as something of a clincher or knock-down argument on their side of the debate.
The second (anti-Cartesian) line of attack relates closely to this because, as Chalmers and Clark see it, the upshot of all those slippery-slope instances if pressed right through is to leave no room – no philosophically habitable space – for the appeal to conscious mind-states as a demarcation criterion. A whole range of basic mental activities, including some (like language-use) of a highly complex and sophisticated kind, are such as not only to proceed for the most part without conscious or deliberative thought but actually to require – for their normal functioning – that this should be the case. So when opponents claim that another salient difference between Otto and Inga is the liability of Otto’s notebook – like all such prostheses – to loss, damage, or sabotage the EM party promptly rejoins that Inga’s brain is liable to the same sorts of accident and, besides that, subject to episodes of distraction, drowsiness, or sleep. The intended effect of all this is to soften up opponents by steadily removing any rational ground they might have (or purport to have) for maintaining the idea of a qualitative difference between mind, intentionality or natural memory and various mind-extending devices like those instanced above. Indeed that effect is clearly visible in the writing of EM theorists where already there has developed a regular tendency to use the language of computing, networks, feedback loops, etc., when describing what would normally – folk-psychologically – dictate the choice of a mentalist or intentionalist idiom. So when Chalmers and Clark rehearse the various standard objections to the EM hypothesis they go so far as to concede the possibility that ‘Inga’s “central” processes and her memory probably have a relatively high-bandwidth link between them, compared to the low-grade connection between Otto and his notebook’.
However this is a concession in which nothing much is conceded since the difference concerned – when phrased and conceived in this manner – is one that works out entirely in favour of their own central proposition. That is to say, their talk of high versus low bandwidths joins onto the nowadays familiar analogy between mind and the central processing unit of a computer so as to suggest that this whole way of thinking has a more than analogical force. What it helps to drive home is the message that memory, along with other aspects of human mental life, should be thought of in resolutely physicalist terms and hence as including any and all of those physical devices that serve to extend its cognitive powers.
Another main area of debate in this context is the distinction between standing and occurrent beliefs, the latter defined as conscious or present-to-mind at some given point in time and the former – by contrast – as those of which we are not conscious or presently aware although we would acknowledge them if asked or act upon them if prompted. This distinction is seen as crucial by the anti-EM party since it arguably falls in with their case for consciousness as the source of ‘underived content’, and hence with their claim that extra-cranial devices simply cannot be integral constituents of mind unless one adopts the pan-psychist idea that everything partakes of consciousness in some, however slight degree. One can therefore understand why Chalmers should profess a certain sympathy with such ideas since the case for panpsychism can readily be stated in terms that fit in well enough with the EM hypothesis, i.e., through its likewise seeking to remove the mind/world barrier, albeit in a more far-reaching way and on no such basically physicalist grounds. From the pro-EM standpoint it is just as crucial to deny that occurrent thoughts, beliefs or memories have any kind of privileged status vis-à-vis standing or dispositional mind-states. After all, the former seem maximally unlikely candidates for replacement or replication by devices outside the skull while the latter are much more readily conceived – though not by Fodor and company – as subject to this or that form of prosthetic extension. So EM advocates typically take the line that since no beliefs are wholly or purely occurrent – since they are all reliant for their power to guide or influence behaviour on a background of standing belief-dispositions – that distinction cannot serve as a basis for rejecting the EM claim.
Here again they deploy a version of the slippery-slope argument, in this case reasoning from the fact that possessors of a normally functioning Inga-type ‘internal’ memory must all the same have recourse, at whatever unconscious or preconscious level, to stored information that cannot plausibly be thought of as punctually present to mind. In short, if the mark of the mental is underived content and if underived content is possessed by occurrent but not by standing beliefs then Inga’s situation in this regard is no different from Otto’s. Or rather, their situations differ in a relative but not in a decisive way since although Inga is no doubt better placed for quick and ready access to her memories without having to consult a notebook she still has the need – conscious or not – to check out the reliability of any knowledge or guidance thus obtained against the stock of information laid down in her standing memory. Of course the opponents of EM will be routinely unimpressed by this argument, on the one hand because (according to them) it once again begs the question by denying, rather than disproving, the existence of underived content and on the other because they (Fodor at least) reject the validity of slippery-slope arguments in general. Besides, they may respond, the point about Inga’s having (like Otto) to ‘consult’ her memory is far less telling than the point that Otto has to believe in the accuracy of his notebook – has to invest it, so to speak, with a quality of credit-worthiness – in a way that necessarily involves the exercise of underived intentional or sense-bestowing powers. To which of course the EM-advocates predictably come back with the further iteration of their basic case: that quite simply there is no such thing as ‘underived content’, and hence that there is no difference – in principle if not for certain practical purposes – between Inga’s and Otto’s situations.
It should be clear by now that this dispute is of the kind – the peculiarly philosophical kind – that is very likely to run and run until boredom sets in, or until there is a switch of interest amongst members of the relevant (largely academic) community. This is not to conclude that it is a ‘merely’ academic dispute, in the sense of having nothing important or relevant to say to anyone outside the community of those with the time and incentive to pursue such matters. On the contrary: it has some large ethical and socio-political implications, as Chalmers makes clear when he remarks that if the EM hypothesis achieves wide acceptance then ‘in some cases interfering with someone’s environment will have the same moral significance as interfering with their person’. Moreover, if physical devices like notebooks and iPhones can qualify as genuinely mind-extending in the strong sense proposed then all the more must this apply to those ‘significant others’ – persons with whom the individual concerned is regularly, closely or intimately in contact – who serve not only as sources of information but (at least under normal circumstances) as active and cooperative members of his or her life-world. Clark and Chalmers acknowledge this, sure enough, but tend to underplay the significance of it or treat it as a non-essential aspect of their case. They prefer to offer instances like that of one’s financial accountant or trusted waiter at a favourite restaurant rather than partners, relatives, or people more personally close-to-home. The reason for this preference is not far to seek since the EM hypothesis is primarily one having to do with processes of information-uptake and information-transfer occurring in a depersonalised context, whether that of Otto’s consulting his notebook or somebody’s consulting their accountant. Even the favourite-waiter example seems to be chosen – fully in line with standard priorities – so as to place greatest emphasis on considerations such as special expertise, reliability, habitual contact, ease of communication, and so forth.
Thus the idea of socially (as opposed to physically or artefactually) extended cognition is one that Clark is willing to endorse – ‘no reason why not’ – but without anything like the partisan vigour that he brings to his argument for the mind-expanding power of notebooks and iPhones. Of course this is hardly surprising given his and Chalmers’ primary emphasis on the ways in which material implements and devices, rather than other minds, have a role in extending our cognitive powers. However it does tend to bias their approach in favour of that physical or techno-prosthetic dimension and thus prevent them from fully acknowledging the depth and extent of those human, social, or inter-subjective dimensions that shape so much of our mental lives. The resultant philosophy of mind is one that inclines not so much toward naturalism as understood by most of its present-day advocates but rather toward a mechanistic conception that so emphatically repudiates one aspect of Cartesian dualism, i.e., that of res cogitans or the mentalist ‘ghost in the machine’ that it ends up by granting pride of place to an all-encompassing res extensa or inertly physical realm.
Of course the phrase ‘inertly physical’ is one that the EM theorists would reject out of hand, implying as it does the existence of an altogether distinct ‘mental’, ‘subjective’, ‘intentional’, ‘phenomenological’, or ‘underived-content’ domain where physicalism meets its ultimate limit in that which transcends any possible physicalist specification. By taking that line – so the charge-sheet runs – the anti-EM brigade are merely buying into the same old vitalist delusion, the idea of some mysterious life-force beyond reach of scientific or rational explanation, that has typified so many reactive movements of thought over the past two centuries and more. However this would be to misidentify the main point at issue in the EM debate, as distinct from the point endlessly belaboured – and to no great avail, on the evidence presented here – by parties on both sides. What really matters, I am suggesting, is not so much the question as normally posed, that is to say, internalism = mentalism + individualism versus extended mind = individual mind/brain + various physical prostheses. Rather it is a different, more searching and relevant question of the form: cognitive individualism = this or that solitary brain + various, chiefly physical prostheses versus the socially extended mind = everything belonging to the human sphere wherein there can be no more sense to the distinction between minds and brains than there is to the distinction between ‘individual’ minds/brains and their range of inter-subjectively salient inputs, contacts, or relationships. That this is not – or not primarily – the kind of question raised by EM theorists should at least give pause to anyone assessing their proposal on grounds of intuitive acceptability.
Of course intuition need not have the last word in these matters, and should probably not be allowed too prominent a voice at any stage in the debate. After all, the progress of scientific knowledge has come about very largely despite and against the weight of (supposed) self-evidence attaching to commonsense-intuitive ideas and beliefs. That history runs from Galileo’s heliocentric hypothesis to the advent of non-Euclidean geometries (with their shock to the Kantian a priori system) and – in consequence – the relativistic conception of space and time. All the same it is far from clear that intuition should always take a back seat when it comes to philosophy of mind or to issues in epistemology which concern that very question of just how far we can or should rely on such apodictic sources. Here at least there is a case – one urged by thinkers in the phenomenological line of descent from Husserl, a tradition oddly conspicuous by its absence from EM debate – that understanding might yet be advanced by a suitably disciplined and rigorous approach to certain intuitions concerning the scope and limits of the properly (non-analogically) mental.
This is not to say – far from it – that any claims in that regard should be subject to assessment on terms laid down by the Cartesian tribunal of conscious awareness or reflective self-knowledge. Indeed few ruling ideas have led to greater wastage of time, effort and ingenuity than the deep-laid philosophical conviction that knowledge must involve a conscious mind-state or some kind of privileged first-person epistemic access. Thus it will count among the most useful services rendered by advocates of strong EM if they manage to shift attention away from the ‘hard problem’ in philosophy of mind, i.e., the famously intractable but (as I have argued elsewhere) much hyped and in the end not very interesting problem of consciousness. On the other hand their way of setting about that worthy task is one that raises some equally intractable problems, among them – as critics like Fodor remark – that of drawing a non-arbitrary line between what properly belongs to mind on this expansive account and what must be considered extra-mental since lacking the requisite degree of informational richness, relevance, complexity, or readiness to hand. This difficulty might best be got over, and without serious detriment to their own case, were the EM theorists a bit more receptive – or a bit less prickly – in their response to the above-cited range of counter-arguments from a broadly phenomenological standpoint. Clark and Chalmers may be right that some of those objections issue from misconceived ideas about the existence of human free-will as dependent on the absolute autonomy of mind, or from a strain of shamefaced Cartesianism that has found another refuge under cover of which to continue the campaign. Thus it now takes the form of a strain of individualism seemingly purged of such dualist residues but squarely opposed to any idea that mind might extend beyond the boundaries of this or that isolated brain, skull, or skin-sack. Such is the diagnosis routinely offered by EM theorists whenever confronted with some argument involving the phenomenological appeal to given aspects of our experiential being-in-the-world, or our placement as so many spatio-temporally located human agents with a certain, albeit at times highly qualified sense of existing within those boundaries.
Indeed his keenness to have done with such arguments leads Clark to suggest that this whole debate might be seen as evidence that ‘the mind is itself too disunified to count as a scientific kind’, and hence to ask: ‘might the EM debate form part of a reductio of the very notion of mind in Cognitive Science?’. In other words, might we not be better off abandoning not only dualism, mentalism, and skin-sack individualism but also – for this would seem to be Clark’s proposal – all those branches of cognitive science and cognitive psychology that find any room for mental or phenomenological predicates? At this stage it strikes me that the only appropriate rejoinder is one that involves babies washed away with the bathwater or noses cut off to spite faces. Where the EM theorists go wrong is by too readily saddling (perceived) opponents with a view of these issues that equates the mental with the conscious, or thought and belief with their surrogate forms – their phantom delegates – in the ‘Cartesian theatre’ of dualist imagining. Otherwise they would have less trouble in conceding that those opponents do have a point, and moreover an EM-compatible point, when they resist going so far as Chalmers and Clark with the project of barrier-dismantling, or with deconstructing categorical distinctions such as that between the mental and the mechanical. More precisely, these objectors – or the cannier among them – think it is worth hanging onto the intuitive distinction between (1) that which is most aptly characterised as belonging to the broadly intentional (i.e., belief-related, thought-involving, cognitive, rational, purposive, or generally mindful) realm and (2) that which it makes better sense to think of as belonging to a different (i.e., physical and extra-cranial) domain, at least when considered under its normal or primary range of descriptions.
It is here – in contesting the mechanistic bias of much EM argument – that Fodor is able to mount his two strongest lines of attack. First, he rejects the kinds of slippery-slope reasoning often used by EM theorists since he considers them to be no more cogent or decisive when deployed in this context than in other set-piece instances like the classical sorites-type (pseudo-)dilemmas. Second, he makes the cardinal point about underived content – or intentionality – as ‘the mark of the mental’ and hence as pertaining to notebooks, maps, GPS units, iPhones, etc., only in a strictly derivative sense or else by the loosest of analogies. As we have seen, Clark and Chalmers are inclined to treat this sort of argument as yet further evidence of backsliding into thoroughly discredited Cartesian ways of thought. Yet the charge clearly lacks force if one construes ‘underived’ not in terms of individual mentality or first-person privileged epistemic access but rather with reference to that wider trans-personal or inter-subjective context in the absence of which human beings would be unable to mean, intend or signify anything whatsoever. This is not to deny the EM thesis in its other, wholly defensible form, namely that those various extra-cranial devices are indeed mind-extending, mind-expanding, and mind-enhancing in a way that changes and might potentially transform the range and scope of our mental capacities. What it does call into doubt is the far-out version of that thesis according to which the history of those developments is sufficient to obliterate the boundary between mind and the various ancillary (no matter how useful, reliable, or even indispensable) devices that have come to play a major role in the lives of many human beings.
That supplements have an odd habit of reversing the normal order of priorities – shifting the emphasis from ‘supplement = mere (strictly unnecessary) add-on or optional extra’ to ‘supplement = that which is needed in order to repair or make good some existing shortfall or deficit’ – is a point that Jacques Derrida demonstrates to brilliant effect in his book Of Grammatology. However it also emerges very strikingly through straightforward reflection on the complex of meanings or logico-semantic implications inherent in these two, on the face of it downright contradictory yet closely entangled senses of the word. It seems to me that this debate around the EM hypothesis has a lot to do with what Derrida calls the ‘logic of supplementarity’ and the kinds of joint reversal-and-displacement to which certain binary distinctions may be subject through a critical account that no longer takes for granted the supposedly self-evident, logical, rational, or ‘natural’ order of priority between them. On the other hand Derrida is equally insistent – as against some other, less canny or cautious exponents of the deconstructive turn – that there is no point in carrying out this inversion of priorities unless it meets the twofold strict requirement exemplified by his own critical practice. That is to say, it must (1) be shown to follow from a rigorous analysis of the terms in question along with the complex, paradoxical, or contradictory relationship between them, and (2) succeed in revealing the strictly unwarranted (i.e., the arbitrary or ideologically motivated) ascription of superiority or dominance to one term over the other.
I cannot see that the strong-EM case meets those requirements or convincingly demands so radical an overhaul of our basic conception of mind vis-à-vis the non-mental or – as the debate is currently played out – the intra– vis-à-vis the extra-cranial. Like Chalmers I do all sorts of things with my iPhone, among them downloading and listening to music, watching films, reading books and journals, accessing the internet, finding my way on bike-rides via GPS (shades of Otto and his notebook), making phone-calls once in a while, taking photos or videos, setting myself maths and logic puzzles, doing sound-recordings (of myself and others), and looking up a whole vast range of otherwise elusive information. Also like Chalmers I am sometimes tempted to think of it as something more literally mind-integral – more closely or intimately bound up with my meanings, intentions, or thought-processes – than could ever be allowed by the more moderate construal of the EM thesis here proposed. This is especially the case when it offers me some otherwise unavailable and life-enriching musical experience or provides ready access to some otherwise inaccessible information-source combined with a capacity for searching out relevant passages and self-addressed memos across all the other devices (desktop, laptop, Kindle etc.) to which my iPhone is linked. However I normally set that temptation aside by reflecting that there is still a great difference between what goes on in my head and what goes on outside it, no matter how much those various externalities may affect, extend, augment or refine my unaided powers of calculation, recollection, logical reasoning, or even – where many would surely dissent – inventive though disciplined hypothesis-construction.
Indeed there is a sense in which the slippery-slope argument beloved of EM enthusiasts can be turned right around and used to challenge their standard line of reasoning. I have been the grateful beneficiary of various electronic music media from LP to CD, Mini-Disc, MP3 and now iTunes and should acknowledge that they have contributed greatly to my mental and physical (not to say spiritual) wellbeing over the years. Still I would be confusing the issue and committing a fairly gross kind of category-mistake if I claimed that the devices in question were literally a part of my musical experience or were bound up with it in some intrinsic and response-constitutive way rather than serving as handy – marvellously handy – technological resources for delivering that experience. The same applies to the distinction between intra-cranial (mental-intentional) and extra-cranial (prosthetic) dimensions of information-processing or whatever goes into the business of cognitive uptake. If that distinction can be made to look delusory or merely naïve then this is no doubt due to the present-day dominance of naturalistic approaches in epistemology and philosophy of mind, and the consequent suspicion that any attempt to draw such a line must be in hock to residual Cartesian ways of thought.
That this objection misfires, since intentionality (or Fodor’s ‘underived content’) can perfectly well go along with a naturalized epistemology, is a case that I have presented in detail elsewhere and which finds support in a good deal of recent work in those same disciplines. What emerges is something more in line with that moderate version of the EM thesis which treats extra-cranial prosthetic devices as no doubt playing all manner of informative, restorative, memory-boosting, intelligence-stretching, creativity-provoking, or other such mentally enhancing roles without for that reason demanding recognition as integral components of mind. Rejecting the lessons of phenomenology or viewing it as merely a species of ‘psychologism’ (for which read: subjectivism/relativism run amok) is one of those deep-laid articles of faith or largely unquestioned imperatives handed down by the founding fathers – Frege in particular – that typify the discourse of mainstream analytic philosophy. Even thinkers who have lately questioned that imperative or sought to negotiate a renewal of ties between the two traditions – an increasing number of late – still tend to assume that Frege got it pretty much right with regard to the irrelevance of phenomenological considerations when it comes to logic and the formal sciences.
It seems to me that this assumption, whether or not valid in that particular context, has exerted a distorting effect when carried over into different areas of debate like those surrounding the strong EM hypothesis. It has led philosophers like Chalmers and Clark to treat any resistance to their case in its full-strength or uncompromising form as just a throwback to quaintly subjectivist or ‘psychologistic’ modes of thought. However this is a flat misunderstanding of the opposition case and one that badly distorts the issue between these contending parties. In short, there is no reason – partisanship or prejudice aside – to suppose that a belief in the distinctness of mind from its various ancillary, prosthetic, or supplementary aids is necessarily a sign of Cartesian leanings. Nor is it to go along with those thinkers – among them followers of Wittgenstein and subscribers to Donald Davidson’s idea of ‘anomalous monism’ – who regard mind-talk and physicalist talk as each making sense in its own proper (topic-relative) sphere, and hence as incapable of coming into conflict except through some categorical confusion or failure to respect their respective scope and limits. Rather it is to recognise that phenomenology can and should have its say in any discussion of these issues, and moreover that this can and should go along with the commitment to a thoroughly naturalised conception of mind and its various attributes. However – crucially – this is a phenomenology of the extended mind where that extension is primarily social or inter-subjective in character, i.e., no longer restricted to the realm of first-person apodictic thought, judgement, and experience that occupied the main focus of Husserlian phenomenological enquiry.
Here it joins with other anti-individualist or trans-personal conceptions, many of which trace their lineage back to Spinoza’s radically heterodox thesis – developed very much in opposition to Descartes – that mind is a properly collective (or multitudinous) phenomenon which gains its power and capacity for action precisely through achieving the maximal extent of inter-active communal exchange. This is why recent intellectual historians have identified Spinozism as the leading force in that largely underground ‘radical enlightenment’ that pressed its social-transformative claims far beyond anything countenanced by the purveyors of ‘official’ enlightenment values and beliefs, Kant chief among them. Thus the idea of ‘multitude’ has nowadays been taken up by a number of thinkers who seek to develop a social-political ontology that would break altogether with the individualist and epistemologically oriented modes of philosophizing bequeathed by Descartes and Kant. One feature of that tradition has been its periodic tendency – above all in Descartes – to combine a subjectivist-idealist appeal to the supposed self-evidence and privileged status of first-person epistemic warrant with an otherwise thoroughly mechanistic worldview, thus squeezing out any notion of mind as manifest through modes of inter-subjective, inter-personal, or ‘multitudinous’ assemblage. It seems to me that the ‘strong’ EM thesis shows a similar penchant for all things physical-mechanical and a similar tendency to downplay the role of those other, more-than-supplementary resources which pertain to mind in its trans-individual dimension.
One need not be a Marxist – though probably it helps – to detect here a telltale symptom of the process (call it reification or commodification) that converts the products of human labour, invention, or creative ingenuity into so many items of inertly physical matter. Of course the advocates of strong EM will again protest that this charge is grossly misconceived since what they are proposing is a radical shift in just the opposite direction, that is, from conceiving notebooks, iPhones, and so forth as physical artefacts and nothing more to conceiving them as animated (so to speak) by human intentionality. Yet it is precisely Marx’s point in his writing on the uncanny ‘logic’ of commodity fetishism that this is indeed a two-way exchange of properties or attributes although one that has the predominant effect of rendering the animate inert rather than vice versa. Thus, in EM terms, the mind-extending powers of extra-cranial devices are routinely extolled without taking adequate account of their dependence on the mind-expanding power of communal or collective human intelligence. This produces a reified, commodified or fetishized conception of technology which in turn leads us to think of human beings as creatures of the various (whether lo-tech or hi-tech) gizmos that are taken to constitute a large and increasingly pervasive aspect of their life-worlds. So there is, I suggest, good reason to resist the more hard-line versions of the EM thesis, or those that take literally its claim that notebooks and iPhones are integral parts of – rather than highly useful, versatile and often much relied-upon additions to – our core repertory of cognitive powers. Otherwise it is likely to result not so much in a newly expansive conception of the mental that embraces all sorts of items hitherto deemed inertly physical but rather, despite what its advocates may claim, in a shift of perception that works to precisely opposite effect.
This likelihood increases as the EM case is pushed beyond cases having to do with memory, knowledge, reasoning, logic, calculation, and the more cognitive or formal-procedural aspects of human intelligence. After all, the whole approach finds its best, most convincing set-piece instances in technologies – whether notebooks or iPhones – that have as their primary function the more efficient marshalling of information or the better working of our rational thought-procedures. As I have said, Chalmers and Clark are by no means unaware of this challenge and indeed make a point of confronting it head-on. Thus to the questions ‘what about socially-extended cognition?’ and ‘could my mental states be partly constituted by the states of other thinkers?’ they respond that ‘in an unusually interdependent couple, it is entirely possible that one partner’s beliefs will play the same sort of role for the other as the notebook plays for Otto’. This does at least take us further into the realm of significant inter-subjective or inter-personal exchange than their allusion to the kind of relationship that people have with their financially trusted accountant or the favourite waiter in their favourite restaurant. Still it doesn’t take us that much further since the interdependent-couple case is one that confines the range of relevant examples to relationships of the most intimate (hence socially exclusive) kind and thereby works to debar any reference to the collective – i.e., the socio-political or ‘multitudinous’ – dimension of human inter-dependent activity.
Chalmers and Clark go on to raise the question as to what consequences flow from an acceptance of the strong EM thesis for our conception of ‘that most problematic entity, the self’. The passage needs quoting at length because it brings out very clearly the effect of such thinking in terms of that wider, i.e., not only trans-individual but also properly public or non-intimate since trans-personal sphere. ‘Does the spread of cognitive processes out into the world imply some correlative leakage of the self into local surroundings?’, they ask. Yes indeed, since it is only the diehard (or shamefaced) Cartesians who would seek to shore up the citadel of the self – or personal identity – against all encroachments from ‘outside’. Thus:
Most of us already accept that the boundaries of the self outstrip the boundaries of consciousness: my dispositional beliefs, for example, constitute in some deep sense part of who I am. If so, then our previous discussion implies that these boundaries may also fall beyond the skin. The information in Otto’s notebook, for example, is a central part of his identity as a cognitive agent. What this comes to is that Otto himself is best regarded as an extended system, a coupling of biological organism and external resources. To consistently resist this conclusion, we should have to shrink the self into a mere bundle of occurrent states, severely threatening the psychological continuity of the self. Far better to take the broader view, and see agents themselves as spread-out into the world.
This passage perfectly exemplifies the way that strong EM uses the bugbear of Cartesian dualism – with all its well-known problems concerning selfhood or personal identity vis-à-vis the ‘external world’ – in order to prop up its case. There are three main issues that it raises with particular force so I shall end this discussion by focussing on them and drawing the relevant conclusions with regard to the EM programme in its currently most visible and vigorous guise.
First: if the boundaries need pushing back then it is far from clear – indeed highly doubtful – that they need pushing so as to include an ever-increasing range of technological appliances, accessories or gadgets that cannot (except on a thoroughly mechanistic worldview) lay claim to a constitutive role in the shaping of human identity. Second: if it is true that mind-world boundaries must be thought of as falling ‘outside the skin’ then getting inside other people’s skins (and allowing them to get inside ours) is more important – more crucial to overcoming that Cartesian legacy – than extending our nominal definition of ‘mind’ to include this or that item of physical paraphernalia. And third: if Otto’s notebook is deemed ‘a central part of his identity as a cognitive agent’ then this claim needs some very careful unpacking. Maybe it qualifies for such a role only in so far as we are considering his ‘identity’ in strictly ‘cognitive’ terms, that is, in line with the bias typically displayed by the advocates of strong EM. But in that case one should surely be given pause by the emphatic claim that ‘Otto himself is best regarded as an extended system, a coupling of biological organism and external resources’. For then it is hard to avoid the conclusion that selfhood and identity must be a matter of states that pertain very largely – perhaps entirely – at an infra-personal, pre-volitional, or sub-doxastic level.
So far from preserving the ‘psychological continuity of the self’ this idea of agents as ‘spread-out into the world’ is much likelier to induce a generalised scepticism with regard to any claim for the self as playing an other than notional or place-filler role. In effect it is squeezed out – reduced to insignificance – by that direct ‘coupling of biological organism and external resources’ that Chalmers and Clark envisage as providing all that’s required in the way of explanatory content. Indeed, the very fact of their resorting to talk of ‘external’ versus ‘internal’ is enough to suggest that the ‘shrinkage’ of the self here imputed to internalists is perhaps more a feature of the EM approach and its reduction of mind to a ‘mere bundle’ of dispositional (rather than occurrent) states. At any rate if there is a genuine threat to the ‘psychological continuity of the self’ then it looms much larger from the EM direction than from any over-emphasis on phenomenological aspects of human thought and experience. Acceptance of the thesis in its strong or literal form is apt to produce an increasingly mechanised image of the mind that ignores or discounts those properties of it – chief among them its distinctive intentionality – which stand in the way of such acceptance. What most needs stressing is the basic point that a theory of mind duly heedful of the relevant distinctions need not (indeed, should not for its own philosophical good) get into conflict with a naturalised conception of mind vis-à-vis brain and its ambient physical and social world. However if attention is focused solely on physical aspects of the extended mind – thus ignoring its social or inter-personal aspects – then this is sure to produce a distorted perspective and a tendency to replicate those same vexing dualisms that the EM proponents hope to have resolved once and for all.
At any rate there is room to doubt Clark’s and Chalmers’ claim – or to find in it a certain revealing ambiguity – when they confidently state that ‘once the hegemony of skin and skull is usurped, we may be able to see ourselves more truly as creatures of the world’. In the strong version it is a thesis with some fairly discomforting overtones for those whose relationship with various items of not-so-peripheral technology may involve a mixture of dependence, fascination, and a sense that we are indeed becoming ‘creatures’ of a world – a world of all-embracing informatics – with designs on the scope and limits of our selfhood.
 David J. Chalmers and Andy Clark, ‘The Extended Mind’, in Richard Menary (ed.), The Extended Mind (Cambridge MA: MIT Press, 2010), pp. 27-42. For further discussions pro and contra the EM thesis, see especially Frederick Adams and Kenneth Aizawa, The Bounds of Cognition (Oxford: Blackwell, 2008); Lynne Rudder Baker, ‘Persons and the Extended Mind Thesis’, Zygon, Vol. 44, No. 3 (2009), pp. 642-58; Andy Clark, Natural-Born Cyborgs: minds, technologies and the future of human intelligence (Oxford: Oxford University Press, 2003), ‘Curing Cognitive Hiccups: a defence of the extended mind’, Journal of Philosophy, Vol. 104, No. 4 (2007), pp. 163-92, and ‘Intrinsic Content, Active Memory, and the Extended Mind’, Analysis, Vol. 65, No. 285 (2005), pp. 1-11; Brie Gertler and Lawrence Shapiro (eds.), Arguing About the Mind (London: Routledge, 2007); Susan Hurley (ed.), Consciousness in Action (Cambridge, MA: Harvard University Press, 1998) and ‘Vehicles, Contents, Conceptual Structure and Externalism’, Analysis, Vol. 58, No. 1 (1998), pp. 1-6; Richard Menary, Cognitive Integration: mind and cognition unbounded (London: Palgrave, 2007); Mark Rowlands, ‘Extended Cognition and the Mark of the Cognitive’, Philosophical Psychology, Vol. 22, No. 1 (2009), pp. 1-19 and ‘The Extended Mind’, Zygon, Vol. 44, No. 3 (2009), pp 628-41.
 Jerry Fodor, ‘Where is my Mind?’, London Review of Books, 31:3 (2009), pp. 13-15.
 See also Fodor Psychosemantics (Cambridge, MA: MIT Press, 1987) and The Elm and the Expert (MIT Press, 1994).
 Fodor, ‘Where is my Mind?’, p. 15.
 John R. Searle, Intentionality: an essay in the philosophy of mind (Cambridge: Cambridge University Press, 1983).
 For a vigorously-argued presentation of the eliminativist or central-state materialist case, see Paul M. Churchland, Scientific Realism and the Plasticity of Mind (Cambridge: Cambridge University Press, 1979).
 For further discussion of this possible convergence between phenomenological and naturalistic conceptions of mind, see Christopher Norris, Minding the Gap: epistemology and philosophy of science in the two traditions (Amherst, MA: University of Massachusetts Press, 2000) and Re-Thinking the Cogito: naturalism, reason and the venture of thought (London: Continuum, 2010).
 Chalmers and Clark, ‘The Extended Mind’ (Note 1, above), p. 29.
 Andy Clark, Supersizing the Mind: embodiment, action and cognitive extension (Oxford: Oxford University Press, 2008).
 Fodor, ‘Where is my Mind?’, p. 13.
 Clark, Supersizing the Mind, p. 96.
 Chalmers and Clark, ‘The Extended Mind’, p. 27 ff.
 See especially Chalmers, The Conscious Mind: in search of a fundamental theory (Oxford: Oxford University Press, 1996).
 Chalmers and Clark, ‘The Extended Mind’, p. 45.
 See for instance Shaun Gallagher and Dan Zahavi, The Phenomenological Mind: an introduction to philosophy of mind and cognitive science (London: Routledge, 2008); Barry Smith and David Woodruff Smith (eds.), The Cambridge Companion to Husserl (Cambridge: Cambridge University Press, 1995); David Woodruff Smith, Husserl (London: Routledge, 2007); Dan Zahavi, Subjectivity and Selfhood: investigating the first-person perspective (Cambridge, MA: MIT Press, 2008).
 Norris, Re-Thinking the Cogito.
 Clark, ‘Memento’s Revenge: the extended mind, extended’, in Menary (ed.), The Extended Mind (Note 1, above), pp. 43-66; p. 65.
 See for instance Adams and Aizawa, The Bounds of Cognition (Note 1, above); also various contributors to Gertler and Shapiro (eds.), Arguing About the Mind and Menary (ed.), The Extended Mind (Note 1). Among others resistant to the EM proposal, at least in its full-strength form, see also Gary Bartlett, ‘Whither Internalism? how internalists should respond to the extended-mind hypothesis’, Metaphilosophy, Vol. 39 (2008), pp. 163-84 and Robert D. Rupert, ‘Challenges to the Hypothesis of Extended Mentation’, Journal of Philosophy, Vol. 101, No. 8 (2004), pp. 389-428. For some wider though highly relevant contexts of debate, see P. Robbins and M. Aydede (eds.), The Cambridge Handbook of Situated Cognition (Cambridge: Cambridge University Press, 2009).
 Jacques Derrida, Of Grammatology, trans. G.C. Spivak (Baltimore, MD: Johns Hopkins University Press, 1976).
 Norris, Re-Thinking the Cogito.
 For a more detailed account, see Norris, ‘Who’s Afraid of Psychologism?: normativity, truth, and epistemic warrant’, in On Truth and Meaning: language, logic and the grounds of belief (London: Continuum, 2006), pp. 12-40.
 See especially Michael Dummett, Origins of Analytical Philosophy (Cambridge, MA: Harvard University Press, 1993).
 See for instance Severin Schroeder (ed.), Wittgenstein and Contemporary Philosophy of Mind (Palgrave-Macmillan, 2001); also Donald Davidson, Essays on Actions and Events, 2nd ed. (Oxford: Oxford University Press, 2001).
 See especially Antonio Negri, The Savage Anomaly: the power of Spinoza’s metaphysics and politics, trans. Michael Hardt (Minneapolis: University of Minnesota Press, 1991); also Gilles Deleuze, Spinoza: practical philosophy, trans. Robert Hurley (San Francisco: City Lights Books, 1988) and Expressionism in Philosophy: Spinoza, trans. Martin Joughin (New York: Zone Books, 1992).
 Jonathan Israel, Radical Enlightenment: philosophy and the making of modernity, 1650-1750 (Oxford: Oxford University Press, 2002); see also Christopher Norris, Spinoza and the Origins of Modern Critical Theory (Oxford: Blackwell, 1991); Paul Wienpahl, The Radical Spinoza (New York: New York University Press, 1979); Yirmiyahu Yovel, Spinoza and Other Heretics, Vol. One: The Marrano of Reason, and Vol. 2, The Adventures of Immanence (Princeton, NY: Princeton University Press, 1989).
 See especially Michael Hardt and Antonio Negri, Empire (Cambridge, MA: Harvard University Press, 2000) and Multitude: war and democracy in the age of empire (New York: Penguin, 2004).
 Karl Marx, Capital, Vol. One, A Critique of Political Economy (Harmondsworth: Penguin, 1992), Chapter One, Section Four.
 Chalmers and Clark, ‘The Extended Mind’, p. 41.