Estrategias de aprendizaje y de enseñanza

An old but still contemporary question about the interpretation of"goals" is whether or not they are best characterised as internal states or external attributes of anagent. This debate dates from the early days of behaviourism in psychology. Most AI researchers and cognitivescientists had until recently espoused the view that intentional states (like belief and desire)usefully could be represented in computers. See (Brachman & Levesque, 1985; Dennett, 1978 Ch. 7;Dennett, 1987 Ch. 6). This view contradicted many of the tenets of behaviourism.

Over the last decade, however, there have been renewed criticisms ofreceived notions of representation in general and of goals and plans in particular. Forinstance, some connectionists have

argued that the use of pointer referenced data-structures must be kept toa strict minimum (Agre, 1988 pp. 182-188). However, the author knows of no cogent argument to theeffect that no internal

representation is used. For instance, although Brooks (1991b) entitledhis paper "Intelligence without representation", he later says that he merely rejects "traditional AIrepresentation schemes" and representations of goals. Hence he is merely suggesting differentrepresentational schemes. Brooks and his colleagues emphasise the importance of interaction between anagent and its environment in determining behaviour, as if this was not obvious to everyone else. In asimilar vein, R. W. White (1959) writes:

Dealing with the environment means carrying on a continuing transactionwhich gradually changes one's relation to the environment. Because there is noconsummatory climax, satisfaction has to be seen as lying in a considerable series oftransactions, in a trend of behavior rather than a goal that is achieved. (p. 322)

These are words that one would expect to find in recent texts on so called"situated activity". (But see (Maes, 1990b) for apostasy within this community.)

A stance needs to be taken in relation to such arguments, since they dobear on the representation of goals. However, this thesis is not the place for asurvey of these fundamental arguments. Instead, one of the clearest positions on these matters isdescribed and evaluated: (Dennett, 1987). Dennett's work is chosen instead of that of AIresearchers such as (Agre, 1988; Agre & Chapman, 1987; Brooks, 1991a), because in my opinion hisarguments are much more sophisticated than theirs. However, his work and that of hisphilosophical sparring partners ( e.g., Fodor, Churchland, and Clark) are very technical and intricate. Dennetthimself characterises the literature as follows: "the mix of contention and invention in theliterature [on propositions] [...] puts it practically off limits to all but the hardy specialists, which isprobably just as well. Others are encouraged to avert their gaze until we get our act together."(Dennett, 1987 p. 205). I nevertheless succumb to the temptation of having a cursory glance at thisliterature.

The Intentional Stance contains a particular class of arguments concerning (1) theinterpretation of intentional terminology and (2) the different ways information canbe stored, manipulated, and used in a system. It is important to view these two classes of argumentas potentially standing separately. G. Ryle (1956) argued that motives are a particular sortof reason for acting (based on a kind of disposition), and neither an occurrence nor a cause of action. Dennett (1987) has developed Ryle's arguments.

Dennett claims that intentional terms in general are simply used bypeople as tools to predict and interpret behaviour on the basis of knowledge of their beliefs anddesires, and not as terms referring to internal mental states, events, or processes. His claim is partlybased on the belief that people do not have access to (nor, presumably, theories about) the design ofeach others minds, and hence that

lay people cannot adopt a "design stance" with respect to one another. Itis also based on analogies between intentional terms and physical "abstracta", things that are notreal but useful for prediction (e.g., gravity). Just as to be five foot tall is not to be in a particularinternal state, to believe that Jon is happy is not to be in a particular state either. Yet either concept canbe used predictively.

Dennett further argues that (propositional) representations should notbe used to model

psychological mechanisms, but to model the worlds in which they shouldoperate. One of Dennett's main justifications of this claim is that he believes thatrepresentationalist theories cannot cope with inconsistencies in beliefs. In particular, he thinks it is difficult forthem to explain behaviour when it breaks down, when it appears irrational. For in such cases, it oftenseems as if a person believes things which are inconsistent. Some of Dennett's more technical argumentshave to do with

philosophical difficulties in specifying the relationship betweenintentional structures—which are in the mind—and their referents—which may be external to the mind(Dennett, 1987). Dennett takes the example of a calculator which though it embodies rules of mathematics,it does not refer to them or use symbols (except in the input and output stages). He claims thatmuch mental processing might be of "that nature".

Dennett's arguments provide a useful reminder that one should not assumethat there is no problem in using intentional representations when designing cognitivesystems. A related but distinct thesis, which is in some respect more general than Dennett's, is thatthe concepts of ordinary

language are often both imprecise and inconsistent and that they must beused with caution. For instance, our concepts of personal identity and life do not permit us to decide whether tele-

transportation—the process of copying a person's molecularcomposition, destroying it, and building a "new" one—involves killing the individual or not. However, thisdoes not imply that we cannot benefit from progressively reformulating these terms. The reformulationscan be judged more on the basis of practical scientific usefulness than consistency with previousterminology (compare Kuhn). Dennett is well aware of the role of conceptual analysis; nevertheless,as is argued below, his proposal to eradicate intentional constructs from designs of systemsseems premature.

In principle, Dennett could give up his proposal to eradicateintentional constructs from designs while maintaining the thesis that intentional constructs can beinterpreted behaviouristically, on the basis that they buy one predictive power, and even that they have somemeasure of "reality".

(Dennett, 1988 pp. 536-8, argues that his view is not strictlyinstrumentalist.) For, it does not follow from the fact that behaviouristic interpretation of terms is very usefuland that it is in a sense real ("abstracta") that representationalist interpretations are empiricallyfalse, philosophically untenable, or that they lead to poor designs: i.e. the two tenets need not be mutually exclusive.

R. S. Peters (1958) critically notes that Ryle lumps together amultifarious compilation of concepts under the dispositional umbrella term "motive". Dennett positsan even broader category of "intentional idioms". Dennett motivates his intentional stance not onlyas an account of beliefs, desires, and intentions, but of folk psychology in general, includingpreferences, goals, intentions, interests "and the other standard terms of folk psychology (Dennett,1987 p. 10). What regroups these terms together? Previous philosophical work answered this questionby saying that they (or at least some of them) were intentional in that they had components thatreferred to something. Dennett does not allow himself the luxury of grouping these terms in theconventional way, yet he refers to a category that is co-extensive with the traditional one, and it does notseem clear that he has a proper category which encompasses them. Intentional now means "folkpsychological", which means "useful for predicting and interpreting behaviour". But what aboutmoods, attitudes, personality traits, and other categories classified above? Although Dennett does notprovide an analysis of these categories, he boldly assumes that they are all to be distinguishedstrictly in terms of how they are used to predict behaviour. Yet, conceptual analysis suggests that someof these terms are not even "intentional" in the sense of previous philosophers. For example,currently some researchers believe that moods have little or no semantic content but can best be understoodin terms of the control they effect (Oatley, 1992; Sloman, 1992b).1 _{As was suggested by Sloman (1992b) and noted above,} control states differ in the precision or extent of their semanticcontent.

Moreover, although Dennett claims that taking the intentional stancebuys one predictive power, he does not provide us with rules to make these predictions, nor does helist this as a topic for future research.

It is not evident that models which use intentional constructs cannotaccount for inconsistencies in beliefs. For instance, in a society of mind theory (Minsky, 1986),it is not impossible for two agents to have different and incompatible beliefs and desires. It is notbecause many theories require that beliefs or preferences be consistent that representationalist AIneeds to be committed to the assumption of consistency. Even within a single module, preferences canbe intransitive or inconsistent. Dennett is very familiar with work in AI. Yet he onlyconsiders a small number of possible explanations of agent level inconsistency (Dennett, 1987 Ch. 4). He provides aninsufficient basis for making sweeping statements about all possible designs. Forinstance, he does not do justice to the broad thesis, developed in (Clark, 1989; Sloman, 1985b), thatit is possible to explain mental phenomena in terms of a number of virtual machines, which use many formsof knowledge

representation, some of which can be described adequately in technicallydefined terms of belief and desire.

1_{However, "moods" are notoriously very difficult to define, and itis possible that the concept is peculiar to}

English speaking cultures. In Québecois French, the closest termis "humeur" and it has a much narrower extension; in that language, there are only two linguisticvariations of 'mood': good mood and bad mood.

This line of argumentation suggests that an important problem withDennett's view is that it does not offer a very practicable methodology for cognitive scientists.Dennett believes that a lot of our knowledge of ourselves uses intentional constructs. Yet he does notwant to allow cognitive scientists to try to tap this knowledge (except in their statement ofthe requirements of the system). This constraint is easy for a philosopher to obey, if he is not in thebusiness of building models; but this is not so for a cognitive scientist. Even if the completeeradication of intentional terminology from cognitive models were ultimately needed—and that is by no meansobvious—it does not follow that cognitive scientists ought not gradually to try to refine and extendintentional constructs in their models. For it is possible that this gradual refinement can lead morerapidly to good models than the alternative which Dennett proposes. In other words, part of thedifficulty with Dennett is that he criticises "folk psychology" writ large on the basis of its purportedinability to give accurate accounts of mental processes. He unjustifiably assumes that the choice is betweena complete rejection of folk psychological categories at the design level and a complete acceptanceof folk psychology at that level. But why make such a dichotomy? Is it not possible to improve someof the categories? After all, scientific physics has progressed by using and improving folkcategories such as space and time. One of the most important difficulties with using folk psychologicalterms is that people use them in different ways. However, this does not prevent a theoretician fromanalysing these concepts and then defining the terms technically. In this thesis an illustration of thispoint is made: progress is made by providing a technical definition of the concept "goal". This definitionis not a lexical one (Copi, 1986 p. 173); i.e., it is not meant accurately to reflect the meaning of the term "goal" asused by laymen. 3.4. Conclusion

In this chapter the concept of goal was expounded. A provisionalhierarchy of control states was described. Goals are a subclass of motivators, and motivators. Thishierarchy needs to be improved, and ways of doing this were suggested. An elaborate notion of goals waspresented. The analysis suggests a richer concept of goal than has been previously supposed.Related work on purposive explanations was reviewed.