In Doing without Concepts, Machery (Reference Machery2009) claims that philosophers and psychologists are not talking about the same thing when they use the term concept, and that this is a consequence of their having differing explanatory interests. But there are reasons to reject Machery's division between philosophical and psychological subject matters regarding concepts. First, we should recognize the significant influence that philosophical and psychological theorizing have had on each other. For instance, prototype theorists have been inspired by philosophical critiques of definitions, theory-theorists have drawn upon philosophical accounts of natural kind terms, and developmental psychologists have prioritized addressing the philosophical challenge of explaining how learning enriches a conceptual system. Likewise, philosophers have been deeply influenced by psychological work on typicality effects, essentialist thinking, and conceptual change in childhood (to name just a few examples). Second, even where philosophers and psychologists do have differing explanatory agendas, the same can be said of just about any two fields in cognitive science and in science generally. Linguists and psychologists have differing explanatory aims too, as do cognitive psychologists and neuro-psychologists – not unlike biologists and chemists. This hardly shows that theorists in these fields aren't talking about the same thing (e.g., NPs, conditioning, or DNA). Third, there is a payoff to identifying a single subject matter that underlies the efforts in philosophy, psychology, and other areas of cognitive science. The result is greater theoretical unification – a prized explanatory virtue.
Now concept is a term of art. But we would suggest that Machery gets off on the wrong foot by characterizing concepts as “bodies of information.” Instead, concepts should be taken to be mental symbols that have semantic structure (which fixes the propositional content of thoughts via a compositional semantics) and processing structure (which explains how concepts figure in various mental processes). Rather than saying that prototypes, exemplars, and theories constitute fundamentally different types of concepts, it is better to locate such bodies of information in a concept's processing structure. On this approach, the concept DOG is akin to a word in a sentence, and its structure includes a prototype, a theory, and so forth (Laurence & Margolis Reference Laurence, Margolis, Margolis and Laurence1999). The principal advantage to viewing concepts in this way is that it makes sense of how philosophers and psychologists can be talking about the same thing, while illuminating the fertile cross-disciplinary interactions that the study of concepts enjoys. And though we (two philosophers) are promoting the idea that concepts are mental symbols, this is not an exclusively philosophical viewpoint. Versions of it are endorsed by many cognitive scientists (e.g., Carey Reference Carey2009; Jackendoff Reference Jackendoff2002; Pinker Reference Pinker1997; Pylyshyn Reference Pylyshyn2007; Sperber & Wilson Reference Sperber and Wilson1995).
Is our account of concepts a hybrid theory? Yes and no. It does bring together prototypes, exemplars, and theories by saying that they are bound to the same mental symbols. The concept DOG, for example, sometimes activates a prototype, sometimes exemplars, and sometimes a theory. But a concept need not have each type of processing structure, and the activation of one part does not require activating other parts. Machery argues that the heterogeneity hypothesis has the explanatory advantage of accounting for the diverse psychological processes that are associated with higher cognitive capacities. But a theory that unites diverse processing structure through links to a common mental symbol can handle this diversity just as well.
Machery asks why theorists who reject the heterogeneity hypothesis do not concede that the various bodies of information (the prototype, theory, etc.) amount to distinct yet co-referential concepts of fundamentally different types – his own view (2009, p. 64). But what justifies Machery's claim that, on his account, a dog prototype, a dog exemplar, and a dog theory are co-referential? To the extent that these representational structures have referents, the referents are hardly likely to be the same. For example, a dog-prototype would refer to things that are similar to the central tendency that the prototype describes, while a dog-theory would cover things that are at odds with the central tendency (e.g., the offspring of two dogs that doesn't look anything like typical dogs). By contrast, on our account, the issue of concept identity is easily handled in terms of the type identity of the mental symbol that unifies these various knowledge structures. This symbol's identity is a matter of what it refers to, plus features of the representation's vehicle for distinguishing among co-referential concepts with differing cognitive significance (Margolis & Laurence Reference Margolis and Laurence2007).
As realists about concepts, we also do not find Machery's case for eliminativism compelling. For one thing, we would argue that concepts as we understand them do constitute a natural kind by Machery's criteria. But also, Machery's standard for the reality of psychological kinds is too high. If his standard were enforced – if a kind has to play an important role in many scientific generalization beyond those that characterize it – we'd have to give up on many core psychological constructs, such as module, computation, and representation. But while these high-level kinds may not satisfy Machery's criteria for realism, they play a key role in describing the mind's operations and helping scientists to empirically investigate its overall organization. Moreover, Machery's standard probably cannot even be maintained for his fundamentally different types of concepts; for example, numerous distinct types of structures tend to get lumped together under the heading of a theory. And though we lack the space to press the point here, Machery's approach to elimination would also have dire consequences outside of psychology. Arguably, we would have to give up most high-level kinds, including cell, vertebrate, and chemical element.
In sum, a realist account of concepts as mental symbols with both semantic and processing structure addresses the explanatory concerns that Machery raises while avoiding the problems connected to his eliminativism. Taking psychological and philosophical theories of concepts to be about a single subject matter allows for far greater theoretical unification, placing concepts at the center of a broad investigation into the nature of cognitive processes, cognitive development, meaning, justification, and the mind's relation to the world.
You have
Access
In Doing without Concepts, Machery (Reference Machery2009) claims that philosophers and psychologists are not talking about the same thing when they use the term concept, and that this is a consequence of their having differing explanatory interests. But there are reasons to reject Machery's division between philosophical and psychological subject matters regarding concepts. First, we should recognize the significant influence that philosophical and psychological theorizing have had on each other. For instance, prototype theorists have been inspired by philosophical critiques of definitions, theory-theorists have drawn upon philosophical accounts of natural kind terms, and developmental psychologists have prioritized addressing the philosophical challenge of explaining how learning enriches a conceptual system. Likewise, philosophers have been deeply influenced by psychological work on typicality effects, essentialist thinking, and conceptual change in childhood (to name just a few examples). Second, even where philosophers and psychologists do have differing explanatory agendas, the same can be said of just about any two fields in cognitive science and in science generally. Linguists and psychologists have differing explanatory aims too, as do cognitive psychologists and neuro-psychologists – not unlike biologists and chemists. This hardly shows that theorists in these fields aren't talking about the same thing (e.g., NPs, conditioning, or DNA). Third, there is a payoff to identifying a single subject matter that underlies the efforts in philosophy, psychology, and other areas of cognitive science. The result is greater theoretical unification – a prized explanatory virtue.
Now concept is a term of art. But we would suggest that Machery gets off on the wrong foot by characterizing concepts as “bodies of information.” Instead, concepts should be taken to be mental symbols that have semantic structure (which fixes the propositional content of thoughts via a compositional semantics) and processing structure (which explains how concepts figure in various mental processes). Rather than saying that prototypes, exemplars, and theories constitute fundamentally different types of concepts, it is better to locate such bodies of information in a concept's processing structure. On this approach, the concept DOG is akin to a word in a sentence, and its structure includes a prototype, a theory, and so forth (Laurence & Margolis Reference Laurence, Margolis, Margolis and Laurence1999). The principal advantage to viewing concepts in this way is that it makes sense of how philosophers and psychologists can be talking about the same thing, while illuminating the fertile cross-disciplinary interactions that the study of concepts enjoys. And though we (two philosophers) are promoting the idea that concepts are mental symbols, this is not an exclusively philosophical viewpoint. Versions of it are endorsed by many cognitive scientists (e.g., Carey Reference Carey2009; Jackendoff Reference Jackendoff2002; Pinker Reference Pinker1997; Pylyshyn Reference Pylyshyn2007; Sperber & Wilson Reference Sperber and Wilson1995).
Is our account of concepts a hybrid theory? Yes and no. It does bring together prototypes, exemplars, and theories by saying that they are bound to the same mental symbols. The concept DOG, for example, sometimes activates a prototype, sometimes exemplars, and sometimes a theory. But a concept need not have each type of processing structure, and the activation of one part does not require activating other parts. Machery argues that the heterogeneity hypothesis has the explanatory advantage of accounting for the diverse psychological processes that are associated with higher cognitive capacities. But a theory that unites diverse processing structure through links to a common mental symbol can handle this diversity just as well.
Machery asks why theorists who reject the heterogeneity hypothesis do not concede that the various bodies of information (the prototype, theory, etc.) amount to distinct yet co-referential concepts of fundamentally different types – his own view (2009, p. 64). But what justifies Machery's claim that, on his account, a dog prototype, a dog exemplar, and a dog theory are co-referential? To the extent that these representational structures have referents, the referents are hardly likely to be the same. For example, a dog-prototype would refer to things that are similar to the central tendency that the prototype describes, while a dog-theory would cover things that are at odds with the central tendency (e.g., the offspring of two dogs that doesn't look anything like typical dogs). By contrast, on our account, the issue of concept identity is easily handled in terms of the type identity of the mental symbol that unifies these various knowledge structures. This symbol's identity is a matter of what it refers to, plus features of the representation's vehicle for distinguishing among co-referential concepts with differing cognitive significance (Margolis & Laurence Reference Margolis and Laurence2007).
As realists about concepts, we also do not find Machery's case for eliminativism compelling. For one thing, we would argue that concepts as we understand them do constitute a natural kind by Machery's criteria. But also, Machery's standard for the reality of psychological kinds is too high. If his standard were enforced – if a kind has to play an important role in many scientific generalization beyond those that characterize it – we'd have to give up on many core psychological constructs, such as module, computation, and representation. But while these high-level kinds may not satisfy Machery's criteria for realism, they play a key role in describing the mind's operations and helping scientists to empirically investigate its overall organization. Moreover, Machery's standard probably cannot even be maintained for his fundamentally different types of concepts; for example, numerous distinct types of structures tend to get lumped together under the heading of a theory. And though we lack the space to press the point here, Machery's approach to elimination would also have dire consequences outside of psychology. Arguably, we would have to give up most high-level kinds, including cell, vertebrate, and chemical element.
In sum, a realist account of concepts as mental symbols with both semantic and processing structure addresses the explanatory concerns that Machery raises while avoiding the problems connected to his eliminativism. Taking psychological and philosophical theories of concepts to be about a single subject matter allows for far greater theoretical unification, placing concepts at the center of a broad investigation into the nature of cognitive processes, cognitive development, meaning, justification, and the mind's relation to the world.
ACKNOWLEDGMENT
Eric Margolis would like to thank Canada's Social Sciences and Humanities Research Council for supporting this research.