Causal Theories of Mental Content

Introduction

Contemporary causal theories of mental content have predecessors dating back to John Locke (Cummins 1989), Aristotle's De Anima, or even to Plato's Theatetus . All such theories develop in the context of some or other representational theory of mind ( RTM ). Contemporary causal theories of mental representation have developed in the theoretical on context of explanation in Cognitive Science. To better understand these theories it is helpful to view their intended role as a explanatory primitive in computation explanations in Cognitive Science.

Cognitive Science seeks to explain the cognitive capacities of humans, animals, and possibly machines. However, the primary thrust of research in Cognitive Science is directed towards explaining human cognitive abilities. More recently theorists have devoted attention to consciousness and emotion.

The classic approach to explaining cognitive capacities within cognitive science has two foundational theses; The "Computational Theory of Cognition" ( CTC ) and the "Representational Theory of Intentionality" ( RTI ). Together these theses dictate the explanatory structure off Cognitive Science. The CTC characterizes cognition as the computation of complex functions on representational states, where computation consists in performing operations defined over the syntactic structures (kinds) of representational states. The RTI asserts that mental states have intentionality (are about the world/have content) in virtue of a representation relation holding between the world and those states. There are three conceptually distinct (though not necessarily temporally distinct) stages. CTC / RTI portrays cognizers as receiving input through sensory organs and/or memory and generating outputs in the form of memories, inputs to other processes, and/or motor response commands.

Cognitive Scientists hotly debate the exact nature of the computational processes involved in cognition. On the one hand, many theorists favor Turing -compatible computation and its development in contemporary computer science and mathematics On the other hand, many theorists favor dynamically described state transitions (ex. Connectionism ). A similar theoretical dichotomy fosters debate in the literature on representation. The two general theoretical approaches towards a theory of representation are " Nomic Covariation " and "Functional Role Semantics". Neither theoretical approach regarding the representation relation presupposed by the RTI has gained general acceptance. However, there are several agreed-upon constraints for a theory of representation. First, the representation relation must be consistent with the physicalistic nature of Cognitive Science. Second, the relation must be present and explanatory in accepted explanations within Cognitive Science. (an appropriate characterization of "accepted" explanations is somewhat controversial). Philosophers particularly would also like to see the accepted theory of representation explain many of the widely accepted properties of belief. Block (1986) and Fodor (1988) provide excellent discussions of the potential problems, the solutions to which many Philosophers hope to find in a theory of mental representation.

Theories

One theoretic approach to articulating the representation relation, Nomic Covariation , postulates a simple causal relationship between the object or property and the state that represents the object or property. The other approach, Functional Role Semantics, hypothesizes that a state has content in virtue of the state's occupying a particular position in a complex web of causal relationships characterizing the cognizer 's functioning (a theory of its psychology). Candidate content-fixing causal relationships include causal relationships within the cognizer (i.e., relations between brain states) and/or without (i.e., relations to the distal environment). Both functional role and Nomic Covariation theories satisfy the (above) first, physicalistic constraint by hypothesizing that a cognizer 's states represent the distal environment solely as a result of the specific sorts of causal connections had by those states. The theories diverge in terms of the specific causal relationships each emphasizes.

Nomic Covariation

Nomic covariation theories hypothesize a causal connection between an object or property in the world and the state that represents that object or property within the cognizer . Information theory as well as work within a sub-field of psychology called psychophysics inspire contemporary Nomic Covariance theorists. Covariation theories, as a result, seem to satisfy the second constraint upon theories of representation, i.e., that the relation must be present and explanatory in accepted explanations within Cognitive Science. For example, Hubel and Wiesel (1977) investigate the representational content of cells in the striate (visual) cortex by monitoring the activity of those cells looking for nomic preferential relationships between the activity of these cells and the presence of properties in the visual field. A system's states represent those objects and/or properties of the distal world with which they covary according to Nomic Covariation theories. Specifically, Nomic covariation theories assign contents to states via some version of the following definition (Cummins 1989, Fodor 1988):

State, Sb, represents B iff the system tokens Sb when, only when, and because of B.

The intuitive appeal of Nomic Covariation stems from the idea that a cognizer represents an object or property by being causally "in tune" with that object or property. Further, Nomic Covariationists such as Jerold Fodor advocate this approach because it assigns content to individual states, Sb independent of how the cognizer operates upon those states (inferences it can make) and/or the content of other states with which Sb might interact. Fodor refers to this assignment of content as " Punctate Content, or "atomic content." Among the advantages claimed by Fodor for punctate content is that it allows for content identity across individuals who have quite different theories regarding some object or property. Similarly, punctate content provides the only theory whereby people can refer to real objects even when they have great numbers of false beliefs about them. For instance, Fodor claims (1992) that Aristotle thought about and talked about the same things we refer to by "stars" even though he falsely believed stars to be relatively close and rotating around the Earth on glassy spheres. A final perceived advantage for Nomic Covariation approaches lies in that they provide a clear-cut mechanism through which a cognizer can come to know about an object or property in the world in virtue of its representational capacities. A cognizer that represents an object or property in the environment does so insofar as it can reliably detect its presence.

Problems for Nomic Covariation

Within Philosophy particularly, but throughout Cognitive Science, theorists raise three standard objections to Nomic Covariation theories. The first objection challenges the ability of covariation theories to explain the representational capacities of states with regard to objects/properties beyond low-level perceptual properties ( e.x. color), especially very abstract, high-level objects and properties like justice or electron. Nomic covariationists suppose that law-like covariation determines the content of states representing properties ranging from low-level properties like red or zero-crossing, to ordinary, medium sized objects and properties like table or cow. States represent properties and objects of a higher level of abstraction, like electron, in virtue of their being defined in terms of the representational properties of lower level states. ( Fodor 1988)

Robert Cummins (1989) objects to this strategy, claiming that covariation of states with objects/properties requires either implicitly or explicitly represented heuristic information in the system. Thus, nomic covariation will not explain the representational properties of any states but the primitive representational states. All higher level concepts from dog to democracy must get meaning through definition. At first glance, it seems plausible to suppose that states that represent high-level theoretical properties like electron get their meaning through definition in terms of lower level properties. After all, such properties and objects often have theoretical definitions. However, the failure of such semantic reductions has shaped the history of Western Philosophy and Mathematics (Quine 1952). Worse still, the lower the level of abstraction, the more ordinary the concept, the less readily one accepts that one knows its meaning because one has an explicit definition for it. For example, covariation 's critics ask why, if the state one uses to represent crow gets its meaning from being defined in terms of lower level properties, why do one have difficulty in articulating that definition in any but the most superficial sense? Psychological research also appears to run contrary to semantic reductionism in that it indicates that object recognition and categorization are strongly influenced by perceptual features, the exact make-up of which is somewhat fluid.

According to Cummins, mental states achieve covariation with cats because we already have explicitly represented or implicit knowledge about cats (ex. they are domesticated felines). Further, the insight that covariation is not the simple, unmediated causal relationship between the property/object and the state, but rather the result of often complex causal interactions within the system, suggests that Nomic Covariation is really just another instance of its competitor, Functional Role Semantics.

The second, and most widely discussed problem for Nomic Covariation theories is called the "Disjunction Problem". According to covariationists , a state represents an object or property if the system tokens (enters into) that state when confronted with the object or property and ONLY WHEN confronted with that property. However, suppose that cognizer tokens a state, Sc, in all of it's cat interactions. According to the WHEN clause of the covariationsist definition, the cognizer 's state appears to represent cathood . Unfortunately, one night the cognizer tokens an Sc when seeing a ferret in the darkness. The ONLY WHEN clause of the definition prima facie dictates that Sc never really represented cat. Rather, the cognizer has always represented a property that we can only describe using the disjunction, "cat or ferret".

The disjunction problem poses difficulties for Nomic Covariation theories in two ways: First, the theory seems to dictate counterintuitive representational contents for states. If one has beliefs about cats, ( e.x. cats are domesticated felines that have a number of distinct breeds), then Nomic Covariation seems to dictate that those beliefs have always been about things having the property of being either a cat or a ferret. Second, the disjunction problem seems to demonstrate that Nomic Covariation cannot account for misrepresentation, since any seeming case of misrepresentation by a cognizer becomes a correct representation of a disjunctive property under Nomic Covariation . In other words, one never mistakenly believes that one sees one's mother at the corner, one always correctly believes that "mother/other" is at the corner.

Theorists have explored a number of solutions to the disjunction problem. All of these solutions rely upon some form of the idealization strategy: A given solution will separate cases of the tokening (occurrence) of a state into two groups, one in which content is already fixed and representational error can occur (normal conditions), and the second class (ideal circumstances) in which content is fixed by perfect covariation . There are several important versions of this solution:

Ideal Conditions

Advocates of the ideal conditions solution to the disjunction problem suggest one represents "mother" and not "mother/other" despite occasionally mistaking others for mothers because under ideal perceptual conditions (i.e., in good light, at close distance, etc.) one can distinguish mothers from others. Idealization in mainstream science is both the inspiration behind the covariationist 's idealization strategy and its source of tacit support. In normal cases of scientific idealization theorists ignore certain negligible parameters in real systems to formulate a law. The resulting law, though not strictly true of any actual system, proves predictively adequate, and quantifies a real relation in actual physical systems.

Consider the following example. Real gases are not composed of Newtonian molecules. Real gas

molecules, that is, are not point masses, nor are their collisions perfectly elastic. Likewise, heat is not the only energy source present in gases. In most cases, however, other parameters (like electromagnetic forces) prove negligible. One can idealize away from such negligible parameters to quantify the inverse relationship between, on the one side, the pressure and volume

of a gas, and on the other side, the temperature and number of moles. Idealizing away from other parameters results in the ideal gas law: PV = nRT .1

The move toward idealization in response to the disjunction problem attempts to emulate noncontroversial cases of scientific idealization like the above-described ideal gas law. The basic idealization move defines representation as follows:

A state Sb represents Bs as Bs iff under ideal circumstances the system tokens a Sb when, only when, and because Bs are present.

On the idealization line, Sb represents cats as cats since, under ideal circumstances, the cognizer tokens Scs when, only when, and because instances of cathood are present. State Sc does not represent cat or ferret because under ideal circumstances ferrets do not cause the cognizer to token Sc. Such an idealization from error, admits the covariationist , breaks down in abnormal circumstances. Nevertheless, the idealization allows psychological laws to capture a real relation (the representation relation) in actual systems. Moreover, since most cases are close to ideal circumstances, psychological laws utilizing idealized nomic covariation prove predictively adequate.

The nomic covariationist 's ideal conditions solution divides tokenings of a state by a system into content-imbuing (ideal) and content-fixed (malfunctioning/atypical) classes. Covariationists assert that one legitimately idealizes away from error because cases of error are coextensive with the cases of malfunction and/or atypical situations from which one legitimately idealizes. For example, if one pulls a weighted spring hard enough to bend or break the spring, it will no longer obey the standard harmonic oscillation equation. Such spring systems do not undermine the the basic physics of dampened harmonic oscilatory systems because the circumstances are such that the spring system cannot operate qua spring system. The same holds for cognitive malfunctions: One's tokening of a Sc as a result of a amphetamine induced psychosis does not introduce disjunctive content because amphetamine induced psychosis is a case of mental malfunction.

Of course, all ferret caused tokenings of Sc will not trace their origins to malfunction. One could token a Sc as a result of the same cat-like features prompting tokenings of Sc for cats. Dismissing such look-alike cases as malfunctioning requires one also dismiss cat cases as malfunctions. All cognition becomes malfunction, if one focuses exclusively upon malfunction. Consider another example.

Subjects normally see a series of wedges in the above picture. In fact, the picture contains a series of straight rows of alternating black and wide squares separated by a thin grey "mortar" line. Psychologist call this the café wall illusion. The illusion demonstrates the effect of some simple image processing occurring at the retina combined with some complex processing in the cortical cells of the striate cortex. The incoming image is filtered by the center-surround operator of the retina (similar to a Laplacian or difference-of- Gaussians operator). If the receptive field of the operator is larger than the mortar width, a set of diagonal bands, similar to Fraser's twisted cords, will appear in place of the mortar line. One can see that the long wedge is actually composed of many individual wedges that are integrated across to produce a long continuous wedge. These findings lead one to conclude that the apparent tilt of the mortar lines is caused by orientation-sensitive simple cells in the striate cortex. These locally tilted components cause a global impression of tilt along the mortar lines. The cells interact with one another to interpret the diagonal bands produced by the retina as a single continuous line, tilted in the direction of the diagonal bands.

The covariationist has a response to such normal functioning cases. When the pressure upon a gas exceeds atmospheric level (1.013 x 105 N/ m2 ), or when its temperature becomes too great, the negligible parameters ignored by the idealized gas law become non-negligible. The predictive accuracy of the idealized gas law plummets. One cannot say that the gas malfunctions. Yet, these cases do not count against the idealized gas law because the circumstances are atypical. The nomic covariationist likewise claims that circumstances are perceptually atypical, that is, less than ideal, when the system tokens a Sc in response to a ferret.

Difficulties arise for the ideal conditions solution when one tries to specify what would count as ideal conditions for a given case in a precise, and non-question-begging manner. For example, in the movie "The Crying Game" an Irish man trying to escape from the IRA becomes romantically involved with a woman. However, much to the surprise of the Irish man (and the audience) this woman is actually a man. The reaction of the Irish man clearly shows he misrepresented the gender of his romantic partner. Yet, the Irish man did see his partner in good light, at close distance, etc.. The natural solution to this difficulty attempts to take advantage of the idea that there are conditions under which such a sex difference would not escape notice. However, in specifying such conditions as ideal conditions for this case, one must be guided in a circular manner by one's knowledge of the property that the state actually represents.

Additionally, critics (Wallis 1994 and 1994a ) also argue that appealing to idealization to defeat the disjunction problem is strongly and negatively disanalogous with successful uses of idealization is science.

Learning Periods

Fred Dretske (1981), has suggested that content gets fixed for a state during a learning period. In this period, cognizer develops a perfect causal connection between the state and the object or property with the help of an instructor who provides examples and corrections. Once the learning period ends, the cognizer 's state has a fixed content and tokenings of the state in cases where the object or property is not present count as misrepresentations.

Fodor (1988) and others have criticized this approach on two grounds. First, there seems to be no principled distinction between learning and non-learning periods, hence no grounds for calling some tokenings of the state content imbuing and others representing or misrepresenting. Second, even if one could specify a learning period, there seems to be no principled distinction between the univocal and disjunctive causal connections. Here critics ask why one might suppose that the causal connection created in the learning period is between, for example, cats and Sc and not between cat/possum and Sc?

Teleological Accounts:

Advocates of a teleological solution to the disjunction problem, such as Ruth Millikan (1983 and 1986), suggest that evolutionary history determines content. For example, a frog captures and eats any ambient moving dot in its visual field. As a result, hungry frogs eat ball-
bearings rolled in front of them. Advocates of the teleological account claim that frogs misrepresent ball-bearings as flies because the function of a frog's visual cells is determined by the uses of those cells responsible for a frog's ability to propagate it's genome, i.e., uses involving fly capturing.

Fodor (1988) criticizes teleological accounts on the ground that evolution does not select with sufficient precision to account for typical univocal content claims. If a frog represents ambient dots as fly or ball-bearing in a fly-rich, ball-bearing-poor environment, then that disjunctive representational content would account for the frog's ability to propagate it's genome. Hence, evolutionary history will not favor fly over fly or ball-bearing as the content of frog visual cells.

Two other objections to teleological accounts appear in the literature. First, most artifacts ( e.x. , compact discs, SUVs , etc.) in the human environment were not present during a significant portion of human evolutionary history. As a result, advocates of teleological solutions to the disjunction problem must explain a huge percentage of the representational capacities of humans, including the representations of many ordinary objects like chairs or beer, by definition. Second, (Cummins 1989) because teleological accounts appeal to the evolutionary history of a cognizer to explain representational abilities, any seeming representational abilities without such a history would not have representational content on the teleological account. For example, if a molecule for molecule duplicate of Millikan where to spontaneously appear, it would seem to have all of her cognitive/representational abilities of Millikan . Yet, on Millikan 's account, her exact double would not have any states with representational content. In other words, one cannot appeal to the adaptational significance of a state to explain its representational content, since in order for the state to have adaptational significance it must play a part in the cognitive capacities the system, and hence already have representational content.

Asymmetric Dependence

Fodor 's (1990) asymmetric dependence theory suggests another twist on the general idealization strategy. In addition to a nomic connection between a state, Sc, and an object/property, cathood , asymmetric dependence defines representation in terms of two counterfactual scenarios: If, say, possums cause Scs , then (1) breaking the possum to Sc connection does not break the cat to Sc and (2) breaking the cat to Sc connection does break the possum to Sc connection. As above, potentially troublesome cases get ruled out because there is a counterfactual set of conditions in which subjects can distinguish cats from possums. Critics (Cummins, 1989 and Wallis 1995) argue that asymmetric dependence theories fares no better than other versions of nomic covariation . One difficulty is that the brain recognizes higher level concepts through the detection of features. As a consequence, it appears that there is no asymmetric dependence between cases, or worse, it goes the wrong way from fake to representation. For instance, if I find my car by looking for features x,y,z , then I can break the car to Scar connection by altering the appearance of my car. But that will not break the look-alike to Scar connection (violating 2). If, on the other hand, I break the look-alike to Scar connection, then it seems I do break the car to Scar connection (violating 1). Similar stories can be told in terms of the normal, albeit somewhat noisy, functioning of cells in the visual system. (Wallis 1995).

Criticisms of the Idealiation Strategy

Functional Role Semantics

Whereas nomic covariationists focus upon a single causal connection in fixing content, advocates of Functional Role Semantics (Block 1986 and 1987, Field 1977 and 1978, Harman 1987), suggest that the overall network of causal relations into which a state can enter fixes its content. Often times causal roles are specified functionally/computationally. Functional Role Semantics is also known as Conceptual Role Semantics, Procedural Semantics, or Inferential Role Semantics. There are two versions of this approach designated "wide" or "long-armed" and "narrow" or "short-armed". Narrow functional role theorists limit the causal relations that determine content to those occuring between mental states. Wide theorists allow connections to the distal environment and even social contexts to delimit the content of a state.

Functional role theories have several attractive features. First, they do not need bifurcated accounts of representational content since all states get their content in the same manner, via their functional role. Hence, functional role theorists avoid explaining the representation of high-level properties by defining them in terms of low-level properties. Second, functional role theorists can easily accommodate the observation that changes in beliefs can result in changes in representational content, since changing beliefs will often change the functional roles of states. Finally, functional role theorists can capture the intuition that in trying to understand the representational content of another cognizer 's state, one is constrained by the heuristic that the overall set of content ascriptions must "make sense," i.e., be consistent with the supposition that overall, the cognizer 's interactions with the world are intelligent or rational.

Objection 1: Semantic Holism

Theorists typically raise three distinct but related objections to all versions of Functional Role Semantics. First, to identify particular states in disparate individuals as states having the same representational content, Functional Role Semantics prima facie requires that the states have identical functional roles. Fodor (1992, 1987) among others has termed this view "Holism," about content (also "Semantic Holism"). For example, suppose that it appears that both Bill and Bob believe that "Wallis' article is enlightening." That is, they both point to the same article, proclaim that it is enlightening, assign it in their class, etc.. However, the causal roles of their respective states differ in a single respect; Bill believes "Wallis is a pompous know-it-all," while Bob believes "Wallis is a precocious windbag." Prima facie, Functional Role Semantics dictates that Bill's belief that "Wallis' article is enlightening," has a different content than Bob's. Similarly, people with disparate cognitive or perceptual abilities seem to have disparate representational contents. Thus, the theory appears to imply that the average human has a different concept of traffic light than color blind humans.

Functional role semanticists generally adopt one of two responses to the above objection. One response strategy would prune the number and/or kind of causal or computational connections necessary for belief/content identity, thereby allowing for belief/content identity across individuals with somewhat different causal/computational roles. In the above case, differences in beliefs that are peripheral to the belief that "Wallis' article is enlightening" would not necessarily constitute the basis for content non-identity.

While the just-rehearsed response has intuitive appeal, critics ( Fodor 1988) point to the potential difficulties in distinguishing core (central) beliefs or other causal links from peripheral ones in a manner that is not hopelessly unsystematic and ad hoc. For instance, what causal connections (beliefs, desires, dispositions to take action, etc..) constitute the core of one's belief that the colorless, tasteless, odorless liquid before one is water. Need one know, to take a case, of the existence of deuterium oxide (heavy water), make appropriate inferences with regard to D2O , discriminate between D2O and H2O, etc.. In the case of beliefs and inferences, one common suggestion for distinguishing core from peripheral beliefs and inferences includes only analytic beliefs and corresponding inferences in the set of core beliefs and inferences. Analytic truths are conceptual truths, those things that are true solely in virtue of the nature of the concept. Such a suggestion requires a real distinction between analytic beliefs and non-analytic (synthetic) beliefs. Many philosophers believe that Quine (1953/1970) has effectively undermined the robustness of such a distinction. Similarly, Stich (1983) argues that judgements of belief/content identity are not as intuitively precise as advocates of the analytic distinction would seem to predict.

The second response to the prima facie difficulty of intuitively identical content across differing functional roles claims that while such beliefs are in fact non-content-identical, they are strongly content similar. The key concept here is the notion that belief identity is not a binary notion, but ranges from completely non-identical to completely identical (Cummins 1989). The strength (or weakness) of this response lies in its ability to accommodate the intuition that Bill's and Bob's beliefs have the same content while simultaneously acknowledging the theoretical constraint that differences in functional roles dictate differences in content.

Critics of Functional Role Semantics (ex. Fodor , 1988) argue that a graded notion of content identity, in addition to being counterintuitive, undermines the ability to formulate psychological generalizations and subsume particular cases under those generalizations. Cognitive Science, they claim, would be reduced to the unworkable notion that Bill's and Bob's beliefs are, say, 97% content similar to the belief that Wallis' article is enlightening and hence can be, say, 97% subsumed under generalizations regarding the belief that Wallis' article is enlightening. Furthermore, Fodor (1992 and 2001) claims colloquial notions of belief similarity like, "His notion of mental representation is similar to mine," as well as their theoretical counterparts presuppose a notion of belief identity that he claims cannot be provided by holistic theories in any cases where beliefs diverge.

Objection 2: Content Fixing, Error, and Univocal Contents

A closely related objection to that of holism is the argument that functional role theories have no non-arbitrary way either of fixing content, distinguishing representational error from veridical representation, and/or they result in non- univocal content ascriptions or multiple content ascriptions applying simultaneously to a given state. For example, suppose that there are two worlds: one, call it Earth1 in which there is no water, but in which D2O (or some chemically different, but phenomenally similar substance) is plentiful; the other, call it Earth2 , where H2O is plentiful, but there is no D2O . Bob grows up on Earth1 , where he forms beliefs, etc. about "water" as a result of interacting with D2O . Bill grows up on Earth2 , where he develops the exact same set of beliefs, etc. about "water" as Bob, but based upon interacting with H2O. If one is a narrow functional role theorist (using only causal connections "internal" to the cognizer ), then the two men must have identical belief content when thinking about "water". They either form beliefs, make inferences, etc., using states that represent what we would describe using the disjunction, "H2O or D2O ", or their states represent both H2O and also D2O (as distinct entities) simultaneously. Most philosophers consider the latter even less intuitively plausible than the former.

Long arm or two factor theories can distinguish Bill's and Bob's beliefs since they include causal connections to environmental objects and/or properties. However, suppose that Bob also has the beliefs that "water is H2O," that "I live on Earth2 ," and " Earth2 has only H2O on it's surface." Is Bob representing "water" as D2O , but forming a false belief about the chemical structure of D2O ? Or, is he representing "water" as H2O and forming false beliefs about the D2O he finds in his environment. Critics assert that Functional Role Semantics lacks the resources to disambiguate such scenarios.

Finally, Fodor and LePore (1992), Fodor and McLaughlin (19891), and Fodor and Plysyhyn (1988) raise the objection that Functional Role Semantics seems to violate truths about the structure of language and thought like compositionality and systemativity . Compositionality is the theory that the meaning of a complex expression in a language results from the meanings of its constitutive elements. Compositionality plays an central role in many linguistic theories, since its supposition for both language and thought provides a fairly straightforward explanation of the human ability to grasp an enormous number of different thoughts of varying complexity and their corresponding linguistic expressions. For instance, because we understand the individual elements like "cup" and "coffee", we understand the complex expressions "cup of coffee," "hot coffee," "coffee gives me the shakes," etc.. One explains our understanding by noting that the meaning of these complex sentences is built-up from the meaning of their constitutive elements.

Fodor and others claim that the functional role of a complex, non-idiomatic representation is not always a function of the functional roles of its parts. As a result, functional role theories like many connectionist representational schemes can represent "cup of coffee" without having the concepts and associated inferences of "cup" or "coffee". This alleged aspect of connectionist representation schemes would result in the possibility that one could represent and think about "cup of coffee," but could not represent or think about "iced coffee," "hot coffee," etc.. Nor could one understand of evaluate the sentence, "Coffee is the legal drug for which we exploit the people and natural resources of many third world countries." Connectionists and others ( Smolensky 1991 and 1991a ) have argued that connectionist systems can have constituents satisfying many of the criteria of compositionality without adopting traditional compositional representational frameworks.

Causal Theories of Mental Content and Cognitive Science

Cognitive Science proceeds in the absence of a resolution of the debate over theories of representation. However, the adoption of either Nomic Covariance Theories or Functional Role Semantics does shape the research of individual cognitive scientists. Many important debates in Cognitive Science have resulted from allegiance to one or the other causal theory. For example, one aspect of the connectionist vs turing compatible approaches is that advocates of connectionist frameworks tend to adopt Functional Role Semantics, while advocates of Turing -compatible frameworks tend to adopt nomic covariation . Similarly, the debate over the nature of mental imagery was drawn along covariance vs functional role lines. It is widely supposed that the adoption of one or the other theory of mental content by the majority of cognitive scientists will have a profound impact on the field.

References

Block, N. (1986) "Advertisement for a Semantics for Psychology," Midwest Studies in Philosophy 9:283-328.

Block, N. (1987) "Functional Role and Truth Conditions," Proceedings of the Aristotelian Society suppl. 61: 157-181.

Cummins, R (1989) Meaning and Mental Representation. Cambridge: MIT Press.

Cummins, R. (1996) Representations, Targets, and Attitudes. Cambridge: MIT Press.

Dretske , F. (1981) Knowledge and the Flow of Information. Cambridge: MIT Press.

Field, H. (1977) "Logic, Meaning, and Conceptual Role," Journal of Philosophy 74: 379-409.

Fodor , J. (1988) Psychosmeantics . Cambridge: MIT Press.

Fodor , J. and Pylyshyn , Z. ( 1988b ). " Connectionism and Cognitive Architecture: A Critical

Analysis," in Cognition. 28: 3-71.

Fodor , J. (1990) A Theory of Content and Other Essays. Cambridge: MIT Press.

Fodor , J. and McLaughlin, B. (1991). " Connectionism and the Problem of Systematicity :

Why Smolensky 's Solution Doesn't Work," Connectionism and the Philosophy of Mind. Boston: Kluwer Academic Publishers.

Fodor , J. and LePore , E. (1992) Holism: A Shoppers' Guide. Oxford: Blackwell.

Fodor , J. (2001) The Mind Doesn't Work That Way. Cambridge: MIT Press.

Harman, G. (1987) "(Non- solipsistic ) Conceptual Role Semantics". New Directions in Semantics, ed. Lepore , E. London: Academic Press.

Hubel, D. and Wiesel, T. (1977) " Ferrier Lecture: Functional Architecture of Macaque Monkey Visual Cortex." Proc. R. Soc. Lond . 198:1-59.

Millikan , R. (1983) Language, Thought and other Biological Categories. Cambridge: MIT Press.

Millikan , R. (1986) "Thought Without Laws: Cognitive Science Without Content." Philosophical Review 95:47-80.

Quine, W. (1953) From a Logical Point of View. Cambridge: Harvard University Press.

Quine, W. (1960) Word and Object. Cambridge: MIT Press.

Smolensky , P. (1991). " Connectionism , Constituency, and the Language of Thought," in G.

Rey and B. Loewer ( eds .) Meaning in Mind. Cambridge: Blackwell.

Smolensky , P. ( 1991a ). "The Constituent Structure of Connectionist Mental States: A Reply

to Fodor and Pylyshyn ," in T. Horgan and J. Tienson ( eds .) Connectionism and the

Philosophy of Mind. Boston: Kluwer Academic Publishers.

Stich , S. (1983) From Folk Psychology to Cognitive Science. Cambridge: MIT Press

Wallis, C. (1994) "Ceteris Paribus Laws and Psychological Explanation," Philosophy of Science Association 1994. 1: 388-397.

Wallis, C. ( 1994a ) "Representation and the Imperfect Ideal," Philosophy of Science. 61: 407-428.

Figure 1 Elements of computational explanations of cognitive capacities in Cognitive Science