il Tao dei baci a vuoto

Se almeno tre delle prossime dieci macchine che l'avesser superato fossero state bianche avrebbe preso il raccordo per Ravenna. Niente, solo una. Si tirava dritto.
Se tre delle prossime sette fossero state guidate da una donna, si sarebbe fermato sulla riviera romagnola. No, soltanto due. Proseguiva.
Se una delle prossime cinque macchine fosse stata una golf, avrebbe dovuto dormire in un motel annesso a un'area di servizio. Qualunque fosse.
Niente, nessuna golf fra le cinque. Guarda te, proprio la sesta.
Si teneva a settanta all'ora, sulla corsia di destra, giusto per tenersi aperta ogni possibilità...

Tao né soprannaturale né meccanico - IV

Thus, there are those who describe “out–of-body experiences”, in which a nonmaterial something (a something which is not a something) is supposed to leave the body in a literal spatial sense, to have percepts and experiences while out on such a trip (although lacking sensory end organs), and to return to the body providing the owner of the body with narratable information about the trip. I regard all such accounts as either dreams or hallucinations or as frank fiction. Similarly, the belief in anthropomorphic supernaturals asserts the existence and ability to influence the course of events of persons who have no location or material existence. Thus, I do not believe in spirits, gods, devas, fairies, leprechauns, nymphs, wood spirits, ghosts, poltergeist, or Santa Claus. (But to learn that there is no Santa Claus is perhaps the beginning of religion.) Some supernatural notions appear to be based in materialistic science but are not on examination, they prove not to have those properties that belong to the world of matter. Of all examples of physical quantities endowed with mental magic, “energy” is the most pernicious. This once neatly defined concept of quantitative physics with real dimensions has become in the talk and thinking of my antimaterialistic friends the explanatory principle to end them all. My position and the reason why so many prefer to believe otherwise may be clarified by an exploration of the relation between religion and magic. I believe that all spells, meditations, incantations, suggestions, procedures of sympathetic and contagious magic, and the like, do indeed work – but they work upon the practitioner (as does “psychic energy”). But I presume that none of these procedures has any effect at all upon any other person unless that other participates in the spell of suggestion or at least has information or expectation that such spell or procedure has been performed. But where these conditions are met and the other person is partly aware of what is being done and aware of its purposes aimed at himself or herself, I am sure that magical procedures can be very effective either to kill or cure, to harm or bless. I do not believe that such magical procedures have relevant effects upon inanimate things. So far so good. I accept no story of action at a distance without communication. But I observe in passing that when the target person participates, the procedure becomes not magic but religion, albeit of a somewhat simple kind.

In general, magical procedures seem to bear formal resemblance to science and to religion. Magic may be a degenerate applied form of either. Consider such rituals as rain dances or the totemic rituals concerned with man‘s relationship to animals. In these types of ritual the human being invokes or imitates or seeks to control the weather or the ecology of wild creatures. But I believe that in their primitive state these are true religious ceremonials. They are ritual statements of unity, involving all the participants in an integration with the meteorological cycle or with the ecology of totemic  animals. This is religion. But the pathway of deterioration from religion to magic is always tempting. From a statement of integration in some often dimly recognized whole, the practitioner turns aside to an appetitive stance. He sees his own ritual as a piece of purposive magic to make the rain come or to promote the fertility of the totemic animal or to achieve some other goal. The criterion that distinguishes magic from religion is, in fact, purpose and especially some extrovert purpose.
Introvert purpose, the desire to change the self, is a very different matter, but intermediate cases occur. If the hunter performs a ritual imitation of an animal to cause the animal to come into his net, that is surely magic, but if his purpose in imitation the animal is perhaps to improve his own empathy and understanding of the beast, his action is perhaps to be classed as religious. My view on magic is converse of that which has been orthodox in anthropology since the days of Sir James Frazer. It is orthodox to believe that religion is an evolutionary development of magic. Magic is regarded as more primitive and religion as its flowering. In contrast, I view sympathetic or contagious magic as a product of decadence from religion; I regard religion on the whole as the earlier condition. I find myself out of sympathy with decadence of this kind either in community life or in the education of children. [The difficulty in all of this is to clarify the sense in which ideas and images do participate in certain kinds of causal chains, although they have neither location nor material being, and to related this to their embodiment in material arrangements, like ink on paper or synaptically linked brain cells. The idea of Santa Claus, communicated through appropriate material networks, can persuade the ten-year-old to clean up his room.]
It is becoming fashionable today to collect narratives about previous incarnations, about travel to some land of the dead, and about existence in some such place, etc. It is, of course, true that many effects of my actions may persist beyond the time of "my" death. My books may continue to be read, but again, this karmic survival does not seem to be what my friends want me to believe. As I see it, after death, the pattern and organization of the living creature are reduced to very simple forms and do not come together again. I can write words on the blackboard and wipe them out. When wiped out, the writing is lost in an entropy of chalk dust. The ideas are something else, but they were never "on" the blackboard in the first place. It must be remembered that at least half of all ideation has no referent in a physical sense, whatsoever. It is the ground that every figure must have. The hole in the bagel defines the torus. When the bagel is eaten, the hole does not remain to me reincarnated in a doughnut. Another form of superstition, exemplified by astrology and divination and by the Jungian theory of synchronicity, seems to arise from the fact that human opinion is strongly biased against the probability of coincidence.

People are commonly surprised by coincidences that are not improbable, for coincidences are much more common than the layman expects. Few coincidences justify the pleased surprise with which they are greeted by those who want to find a supernatural base for them. If things turn out to coincide with our desires, or with our fears, or with other things, we are sure that this was no accident. Either “luck” was on our side or it was against us. Or perhaps our fears caused things to be as they are. And so on. But indeed the efficacy of prayer and/or meditation as a technique for changing ourselves would seem to give an experiential basis for superstitions of this kind. People do not easily distinguish between changes in the self and changes in the world around them. For the rest, I find it hard to be interested in coincidence. It is of interest that harbouring superstition of one kind may lead to another, notably, for example, Arthur Koestler, starting from Marxism, achieved a repudiation of that metaphysical belief and progressed to a belief in synchronicity. Facilis decensus Averno; the descent to hell is easy. Koestler then progressed to arguing for the inheritance of acquired characteristics in The Case of the Midwife Toad. To believe in heredity of this kind is to believe in the transmission of patterned information without a receptor. It is notable also that belief in certain kinds of superstition moves rapidly to a willingness to indulge in trickery to reinforce that belief. [Indeed, the ethnography of shamanism is replete with examples in which the shaman, genuinely believing in his or her magical powers, still uses elaborate and practiced sleight of hand to help out the supernatural. There is sometimes a confusion between different kinds of validity,] as when right brain notions, which have their own kind of validity, are treated as if they have the validity of left-brain thinking. To repudiate the established ways of thought and control is, however, a very different matter from criticizing elements in the counterculture. I can make a list of items in the counterculture with which I do not agree, as I have done here, because a lack of tight integration or consistency is one of their principal characteristics. To quote Kipling, “In the Neolithic Age!": "There are nine and sixty ways of constructing tribal lays, And—every—one—of—them—is—right!” But my objections to the established system are of a different order. I cannot make a list of the pieces. My objection is not to pieces but is a response to the entire way in which many otherwise sensible components of culture such as money or mathematics or experimentation have been fitted together.

More important than all the species of supernaturalist superstition listed above, I find that there are two basic beliefs, intimately connected which are both obsolete and dangerous, and which are shared by contemporary supernaturalists and by prestigious and mechanistic scientists. The mass of superstition now fashionable even among behavioural scientists and physicists springs from a combination of these two fundamental and erroneous beliefs. It is a strange fact that both of these beliefs are connected to the same giant of philosophic thought, René Descartes. Both beliefs are quite familiar.
The first is the idea that underlies the whole range of modern superstition, namely that there are two distinct explanatory principles in our world, "mind" and "matter". As such dichotomies invariably must, this famous Cartesian dualism has spawned a whole host of other splits as monstrous as itself: mind/body; intellect/affect; will/temptation; and so on. It was difficult in the seventeenth century to imagine any nonsupernatural explanation of mental phenomena, and at that time it was already apparent that the physical explanations of astronomy were going to be enormously successful. It was therefore quite natural to fall back upon age-old supernaturalism to get the problems of “mind out of the way”. This accomplished, the scientists could proceed with their “objective” inquiries, disregarding or denying the fact that the organs of sense, indeed our whole range of approaches to study of “matter,” are very far from being “objective”. Descartes‘ other contribution also bears his name and is taught to every child who enters a scientific lab or reads a scientific book. Of all ideas about how to think like a scientist, the idea of using intersecting coordinates, the so-called Cartesian coordinates, to represent two or more interacting variables or represent the course of one variable over time, has been among the most successful. The whole of analytic geometry sprang from this idea, and from analytic geometry the calculus of infinitesimals and the emphasis upon quantity in our scientific understanding. Of course, there can be no cavil at all that. And yet, by the pricking of my thumbs, I am sure that it was no accident that the same man who invented the coordinates, which are among the most materialistic and hard-nosed of scientific devices, also dignified dualistic superstition by asserting the split between mind an matter.
The two ideas are intimately related. And the relation between them is most clearly seen when we think of the mind/matter dualism as a device for removing one half of the problem for explanation from that other half which could more easily be explained. Once separated, mental phenomena could be ignored. This act of subtraction, of course, left the half that could be explained as excessively materialistic, while the other half became totally supernatural. Raw edges have been left on both sides and materialistic science has concealed this wound by generating its own set superstitions. The materialist superstition is the belief (not usually stated that quantity (a purely material notion) can determine pattern.

Tao né soprannaturale né meccanico - III

Tao in D major

Mount Pleasant Cemetery, Toronto, Ontario, Canada

il Te del Tao: XLV - L'IMMENSA VIRTÙ

image by uk-dave

XLV - L'IMMENSA VIRTÙ

La grande completezza è come spezzettamento
che nell'uso non si rompe,
la grande pienezza è come vuotezza
che nell'uso non si esaurisce,
la grande dirittura è come sinuosità,
la grande abilità è come inettitudine,
la grande eloquenza è come balbettio.
L'agitazione finisce nell'algore,
la quiete finisce nel calore:
la pura quiete è la regola del mondo.

Tao e motociclette: logica

Ora voglio continuare l'inseguimento del fantasma della razionalità, questo fantasma classico, noioso e complesso della forma soggiacente.

Stamattina ho parlato delle gerarchie del pensiero — del sistema. Adesso parlerò dei metodi per aprirsi un varco attraverso queste gerarchie: parlerò della logica.

Si usano due tipi di logica: la logica induttiva e la logica deduttiva. La prima parte dall'osservazione della macchina per arrivare a conclusioni generali. Per esempio: la moto supera una serie di cunette e ogni volta il motore perde colpi. Su un tratto di strada liscio corre senza perdere colpi, poi supera un'altra cunetta e il motore perde di nuovo colpi. Qui si può concludere logicamente che la perdita di colpi è causata dalle cunette.

La deduzione segue il processo inverso, ovvero parte da un conoscenza generale per prevedere un'osservazione specifica. Per esempio, se chi lavora sulla moto ha letto la descrizione gerarchica della struttura della moto stessa e sa che il clacson è alimentato esclusivamente dalla batteria, può dedurre logicamente che se la batteria è scarica il clacson non funzionerà. Questa è una deduzione.

Certi problemi, troppo complicati per il senso comune, possono essere risolti solo grazie a una lunga catena di ragionamenti, tanto induttivi che deduttivi, che fanno la spola tra la macchina osservata e la gerarchia  mentale della macchina descritta nei manuali. L'uso corretto di questi ragionamenti è codificato dal metodo scientifico.

A dire il vero non ho mai visto un problema di manutenzione della motocicletta abbastanza complesso da richiedere un vero e proprio metodo scientifico formale. I problemi di riparazione non sono tanto difficili. Quando penso al metodo scientifico formale a volte mi si presenta alla mente l'immagine di un enorme bulldozer — lento, tedioso, ingombrante, laborioso, ma invincibile. Ci vuole il doppio del tempo che non applicando le tecniche empiriche di un meccanico, ma puoi star sicuro che alla fine ce la farai.

Per seguire il metodo scientifico si tiene un quaderno di lavoro. Bisogna scriverci tutto con precisione, in modo da avere sempre il quadro della situazione. A volte basta annotare i problemi per chiarirsi le idee.

Gli enunciati logici da annotare sul quaderno sono da dividere in sei categorie:
1. Enunciato del problema. 2. Ipotesi sulle cause del problema. 3. Esperimenti destinati a verificare ciascuna ipotesi. 4. Risultati probabili degli esperimenti. 5. Risultati effettivi degli esperimenti. 6. Conclusioni sulla base dei risultati degli esperimenti.
Questa elaborazione non è diversa da quella delle esercitazioni di laboratorio di molte scuole e università, ma qui lo scopo non è solo quello di fare esercizi astratti. Lo scopo qui è di orientare il pensiero in modo preciso. Il vero scopo del metodo scientifico è quello di accertare che la natura non ti abbia indotto a credere di sapere quello che non sai. Non esiste un solo meccanico, scienziato o tecnico che non sia stato soggetto a quest'illusione tanto da stare istintivamente in guardia. È soprattutto per questo che i trattati scientifici e le istruzioni meccaniche sembrano così noiosi e pedanti. Le negligenze e le fantasie romantiche in campo scientifico fanno dei brutti scherzi, e la natura imbroglia già abbastanza da sola senza che gliene diamo noi l'occasione. Alla prima deduzione falsa riguardo al motore, ci si ritrova irrimediabilmente bloccati. Per quanto riguarda il punto 1 (Enunciato del problema), l'abilità principale consiste nel non dire assolutamente più di quanto non si sia sicuri di sapere. È molto meglio un'annotazione del tipo: «Problema: perché la motocicletta non funziona?», che sembra poco furba ma è corretta, che scrivere: «Problema: Cos'è che non va nell'impianto elettrico?» se non si è assolutamente sicuri che il guasto sia nell'impianto elettrico. La cosa giusta da scrivere è: «Problema: Cos'è che non va nella moto?» , e poi mettere al primo posto al punto 2: «Ipotesi Numero 1: Il guasto è nell'impianto elettrico». Si pensa al maggior numero di ipotesi possibile, poi si progettano gli esperimenti per verificarle e vedere quali sono vere e quali sono false.

Questo cauto approccio alle domande iniziali vi impedirà di imboccare la strada sbagliata risparmiandovi una settimana di lavoro o addirittura una impasse totale. Spesso le domande scientifiche sembrano a tutta prima poco furbe proprio per questa ragione, ma si formulano al fine di evitare errori poco furbi in seguito.

La sperimentazione (il punto 3) viene vista a volte dai romantici come la scienza nel suo complesso, perché è la più appariscente: loro si immaginano un mucchio di provette, attrezzature bizzarre e gente affaccendata a far scoperte. Non vedono l'esperimento come parte di un più vasto processo intellettuale, e confondono spesso esperimenti e dimostrazioni, i quali, in effetti, si somigliano. Uno scienziato da baraccone che, con una attrezzatura alla Frankenstein, faccia sensazionali ' esperimenti scientifici ', sa in anticipo i risultati dei suoi tramestii e quindi non fa affatto un lavoro scientifico. In compenso, un meccanico che suona il clacson della moto per vedere se la batteria è carica, fa, in modo informale, un vero e proprio esperimento scientifico, poiché verifica un'ipotesi facendo la domanda direttamente alla natura. Lo scienziato televisivo che borbotta tristemente: «L'esperimento è un fiasco; non siamo riusciti a ottenere quello che speravamo» è vittima di un copione scadente. Un esperimento che non ottenga i risultati previsti non è un fiasco. Lo è solo quando non fornisce alcuna conclusione valida, in un senso o nell'altro, rispetto alle ipotesi di partenza.

A questo punto l'abilità sta nel valersi di esperimenti che verifichino solo le ipotesi formulate, niente di meno e niente di più. Se il clacson suona, e il meccanico conclude che tutto l'impianto elettrico funziona, trae una conclusione illogica. Il suono del clacson dimostra solo che funzionano la batteria e il clacson. Per programmare un esperimento in modo adeguato, il meccanico deve porsi, in modo estremamente preciso, il problema delle cause: cioè di cosa provoca direttamente qualcos'altro. E questo lo può stabilire in base alle gerarchie. È nelle candele che l'impianto elettrico causa direttamente l'accensione del motore, e se non si fa una verifica in quel punto non si potrà mai sapere veramente se il guasto è di origine elettrica o no.

Per una verifica precisa il meccanico toglie le candele e le appoggia al motore in modo da stabilire un contatto elettrico, preme la leva dell'avviamento e guarda la candela in attesa di una scintilla azzurra. Se la scintilla non scocca, ci sono due possibilità: a) c'è un guasto elettrico; oppure b) il suo esperimento è mal fatto. Un meccanico esperto lo ripeterà ancora un paio di volte, verificherà i contatti e cercherà in tutti i modi di far scoccare la scintilla. Se non ci riesce, arriverà alla conclusione che a è corretto, cioè che c'è un guasto elettrico, e l'esperimento è concluso: egli ha verificato la sua ipotesi.

Per quanto riguarda il punto finale, le conclusioni, l'abilità sta nel non affermare più di quanto l'esperimento non abbia dimostrato. In questo caso, ad esempio, esso non ha dimostrato che, una volta riparato l'impianto elettrico, la motocicletta partirà. Ci può essere qualcos'altro che non funziona. Ma il meccanico sa per certo che la motocicletta non funzionerà finché non funzioni l'impianto elettrico, per cui formulerà la seguente domanda formale: «Problema: Cos'è che non va nell'impianto elettrico?».

Poi formulerà delle ipotesi in base a questa domanda e le verificherà. Facendo le domande giuste, scegliendo le verifiche giuste e traendo le giuste conclusioni il meccanico si farà strada attraverso i vari gradi della gerarchia  della motocicletta fin quando non troverà la causa o le cause specifiche del guasto al motore, e poi le sopprimerà in modo che non causino più il guasto.

Un osservatore inesperto vedrà solo il lavoro fisico, ma questo non è che l'aspetto più banale. La parte di gran lunga più impegnativa è l'attenta osservazione e il rigore operativo. Questo è il motivo per cui i meccanici al lavoro hanno un'aria così scostante: non vogliono essere distratti perché si stanno concentrando su immagini mentali, su gerarchie, e non sulla motocicletta nella sua materialità. Stanno usando gli esperimenti per allargare la gerarchia della loro conoscenza della motocicletta guasta e paragonarla alla gerarchia corretta che hanno in testa. Stanno guardando la forma soggiacente.

cognizione del Tao: storia e ipotesi

© Igor Morski

Gli autori proseguono l'analisi dei vari approcci alle scienze della cognizione esaminando il filone principale - il cognitivismo - e delineandone l'evoluzione storica e i punti centrali dell'ipotesi di base - la cognizione intesa come computazione di rappresentazioni espresse tramite simboli, nel cervello o in una macchina:

Symbols: The Cognitivist Hypothesis

The Foundational Cloud

Our exploration of cognitive science and human experience begins in this chapter with an examination of cognitivism - the center of our diagram - and its historical origins in the earlier, cybernetic era of cognitive science. The main idea to be presented … is that the analysis of mind undertaken by certain traditions of mindfulness/awareness provides a natural counterpart to present-day cognitivist conceptions of mind. This chapter presents the cognitivist perspective.

Let us begin by looking at the historical roots of present-day cognitivism. This short historical excursion is necessary, for a science that neglects its past is bound to repeat its mistakes and will be unable to visualize its development. Our excursion here is, of course, not intended to be a comprehensive history but only to touch on those issues of direct relevance for our concerns here. In fact, virtually all of the themes in present-day debates were already introduced in the formative years of cognitive science from 1943 to 1953. History indicates, then, that these themes are deep and hard to pursue. The "founding fathers" knew very well that their concerns amounted to a new science, and they christened this science with the new name cybernetics. This name is no longer in current use, and many cognitive scientists today would not even recognize the family connections. This lack of recognition is not idle. It reflects the fact that to become established as a science in its clear-cut cognitivist orientation, the future cognitive science had to sever itself from its roots, which were complex and entangled but also rich with possibilities for growth and development. Such a severance is often the case in the history of science: it is the price of passing from an exploratory stage to a full-fledged research program - from a cloud to a crystal. The cybernetics phase of cognitive science produced an amazing array of concrete results, in addition to its long-term (often underground) influence:

• The use of mathematical logic to understand the operation of the nervous system
• The invention of information-processing machines (such as digital computers), thereby laying the basis for artificial intelligence
• The establishment of the metadiscipline of systems theory, which has had an imprint in many branches of science, such as engineering (systems analysis, control theory), biology (regulatory physiology, ecology), social sciences (family therapy, structural anthropology, management, urban studies), and economics (game theory)
• Information theory as a statistical theory of signal and communication channels
• The first examples of self-organizing systems

This list is impressive: we tend to consider many of these notions and tools an integral part of our lives. Yet they were all nonexistent before this formative decade, and they were all produced by an intense exchange among people of widely different backgrounds. Thus the work during this era was the result of a uniquely and remarkably successful interdisciplinary effort. The avowed intention of this cybernetics movement was to create a science of mind. In the eyes of the leaders of this movement, the study of mental phenomena had been far too long in the hands of psychologists and philosophers. In contrast, these cyberneticians felt a calling to express the processes underlying mental phenomena in explicit mechanisms and mathematical formalisms.

One of the best illustrations of this mode of thinking (and its tangible consequences) was the seminal 1943 paper by Warren McCulloch and Walter Pitts, “A Logical Calculus of Ideas Immanent inNervous Activity.” Two major leaps were taken in this article: first, the proposal that logic is the proper discipline with which to understand the brain and mental activity, and second, the claim that the brain is a device that embodies logical principles in its component elements or neurons. Each neuron was seen as a threshold device, which could be either active or inactive. Such simple neurons could then be connected to one another, their interconnections performing the role of logical operations so that the entire brain could be regarded as a deductive machine.

These ideas were central for the invention of digital computers. At that time, vacuum tubes were used to implement the McCulloch-Pitts neurons whereas today we find silicon chips, but modem computers are still built on the same so-called von Neumann architecture that has been made familiar with the advent of personal computers. This major technological breakthrough also laid the basis for the dominant approach to the scientific study of mind that was to crystalize in the next decade as the cognitivist paradigm.

In fact, Warren McCulloch, more than any other figure, can serve as an exemplar of the hopes and the debates of these formative years. As can be gleaned from his collected papers in Embodiments of Mind, McCulloch was a mysterious and paradoxical figure whose tone was often poetic and prophetic. His influence seemed to wane during the later years of his life, but his legacy is being reconsidered as cognitive science becomes more aware that a thorough intertwining of the philosophical, the empirical, and the mathematical, which McCulloch's investigations exemplified, seems the best way to continue working.

His favorite description for his enterprise was "experimental epistemology" - an expression not favored by current usage. It is one of those remarkable simultaneities in the history of ideas that in the 1940s the Swiss psychologist Jean Piaget coined the expression "genetic epistemology" for his influential work, and the Austrian zoologist Konrad Lorenz started to speak of an "evolutionary epistemology."

There was, of course, considerably more to this creative decade. For instance, there was extensive debate over whether logic is indeed sufficient to understand the brain's operations, since logic neglects the brain's distributed qualities. (This debate continues today, and we will consider it in more detail later, especially as it relates to the question of "levels of explanation" in the study of cognition.) Alternative models and theories were put forth, which for the most part were to lie dormant until they were revived in the 1970s as an important alternative in cognitive science.

By 1953 the main actors of the cybernetics movement, in contrast to their initial unity and vitality, were distanced from each other, and many died shortly thereafter. It was mainly the idea of mind as logical calculation that continued.

Defining the Cognitivist Hypothesis

Just as 1943 was clearly the year in which the cybernetics phase was born, so 1956 was clearly the year that gave birth to cognitivism. During this year, at two meetings held at Cambridge and Dartmouth, new voices (such as those of Herbert Simon, Noam Chomsky, Marvin Minsky, and John McCarthy) put forth ideas that were to become the major guidelines for modern cognitive science.

The central intuition behind cognitivism is that intelligence - human intelligence included -so resembles computation in its essential characteristics that cognition can actually be defined as computations of symbolic representations. Clearly this orientation could not have emerged without the basis laid during the previous decade. The main difference was that one of the many original, tentative ideas was now promoted to a full-blown hypothesis, with a strong desire to set its boundaries apart from its broader, exploratory, and interdisciplinary roots, where the social and biological sciences figured preeminently with all their multifarious complexity.

What exactly does it mean to say that cognition can be defined as computation? As we mentioned a computation is an operation that is carried out or performed on symbols (on elements that represent what they stand for). The key notion here is that of representation or "intentionality," the philosopher's term for aboutness. The cognitivist argument is that intelligent behavior presupposes the ability to represent the world as being certain ways. We therefore cannot explain cognitive behavior unless we assume that an agent acts by representing relevant features of her situations. To the extent that her representation of a situation is accurate, the agent's behavior will be successful (all other things being equal).

This notion of representation is - at least since the demise of behaviorism - relatively uncontroversial. What is controversial is the next step, which is the cognitivist claim that the only way we can account for intelligence and intentionality is to hypothesize that cognition consists of acting on the basis of representations that are physically realized in the form of a symbolic code in the brain or a machine.

According to the cognitivist, the problem that must be solved is how to correlate the ascription of intentional or representational states (beliefs, desires, intentions, etc.) with the physical changes that an agent undergoes in acting. In other words, if we wish to claim that intentional states have causal properties, we have to show not only how those states are physically possible but how they can cause behavior. Here is where the notion of symbolic computation comes in.

Symbols are both physical and have semantic values. Computations are operations on symbols that respect or are constrained by those semantic values. In other words, a computation is fundamentally semantic or representational - we cannot make sense of the idea of computation (as opposed to some random or arbitrary operation on symbols) without adverting to the semantic relations among the symbolic expressions. (This is the meaning of the popular slogan "no computation without representation.") A digital computer, however, operates only on the physical form of the symbols it computes; it has no access to their semantic value. Its operations are nonetheless semantically constrained because every semantic distinction relevant to its program has been encoded in the syntax of its symbolic language by the programmers. In a computer, that is, syntax mirrors or is parallel to the (ascribed) semantics. The cognitivist claim, then, is that this parallelism shows us how intelligence and intentionality (semantics) are physically and mechanically possible. Thus the hypothesis is that computers provide a mechanical model of thought or, in other words, that thought consists of physical, symbolic computations. Cognitive science becomes the study of such cognitive, physical symbol systems.

To understand this hypothesis properly, it is crucial to realize the level at which it is proposed. The cognitivist is not claiming that if we were to open up someone's head and look at the brain, we would find little symbols being manipulated there. Although the symbolic level is physically realized, it is not reducible to the physical level. This point is intuitively obvious when we remember that the same symbol can be realized in numerous physical forms. Because of this nonreducibility it is quite possible that what corresponds to some symbolic expression at the physical level is a global, highly distributed pattern of brain activity. We will return to consider this idea later. For now the point to be emphasized is that in addition to the levels of physics and neurobiology, cognitivism postulates a distinct, irreducible symbolic level in the explanation of cognition. Furthermore, since symbols are semantic items, cognitivists also postulate a third distinctly semantic or representational level. (The irreducibility of this level too is intuitively obvious when we remember that the same semantic value can be realized in numerous symbolic forms.)

This multilevel conception of scientific explanation is quite recent and is one of the major innovations of cognitive science. The roots and initial formulation of the innovation as a broad scientific idea can be traced back to the era of cybernetics, but cognitivists have contributed greatly to its further rigorous philosophical articulation. We would like the reader to keep this idea in mind, for it will take on added significance when we tum to discuss the related - though still controversial - notion of emergence.

The reader should also notice that the cognitivist hypothesis entails a very strong claim about the relations between syntax and semantics. As we mentioned, in a computer program the syntax of the symbolic code mirrors or encodes its semantics. In the case of human language, it is far from obvious that all of the semantic distinctions relevant in an explanation of behavior can be mirrored syntactically. Indeed, many philosophical arguments can be given against this idea. Furthermore, although we know where the semantic level of a computer's computations comes from (the programmers), we have no idea how the symbolic expressions supposed by the cognitivist to be encoded in the brain would get their meaning.

Since our concern is with experience and cognition in its basic, perceptual modality, we will not take up such issues about language in detail here. Nonetheless, they are worth pointing out, since they are problems that lie at the heart of the cognitivist endeavor.

The cognitivist research program can be summarized, then, as answers to the following fundamental questions:

Question 1: What is cognition?

Answer: Information processing as symbolic computation-rule-based manipulation of symbols.

Question 2: How does it work?

Answer: Through any device that can support and manipulate discrete functional elements-the symbols. The system interacts only with the form of the symbols (their physical attributes), not their meaning.

Question 3: How do I know when a cognitive system is functioning adequately?

Answer: When the symbols appropriately represent some aspect of the real world, and the information processing leads to a successful solution of the problem given to the system.

10 Tao