BEHAVIORAL AND BRAIN SCIENCES (2011) 34, 113–167 doi:10.1017/S0140525X10000919 Pre´cis of The Origin of Concepts Susan Carey Department of Psychology, Harvard University, Cambridge, MA 02138 [email protected] Abstract: A theory of conceptual development must specify the innate representational primitives, must characterize the ways in which the initial state differs from the adult state, and must characterize the processes through which one is transformed into the other. The Origin of Concepts (henceforth TOOC) defends three theses. With respect to the initial state, the innate stock of primitives is not limited to sensory, perceptual, or sensorimotor representations; rather, there are also innate conceptual representations. With respect to developmental change, conceptual development consists of episodes of qualitative change, resulting in systems of representation that are more powerful than, and sometimes incommensurable with, those from which they are built. With respect to a learning mechanism that achieves conceptual discontinuity, I offer Quinian bootstrapping. TOOC concludes with a discussion of how an understanding of conceptual development constrains a theory of concepts. Keywords: bootstrapping; concept; core cognition; developmental discontinuity; innate primitive 1. Introduction determines the content of any given mental symbol (i.e., what determines which concept it is, what determines The human conceptual repertoire is a unique phenom- the symbol’s meaning). (In the context of theories of enon, posing a formidable challenge to the disciplines of mental or linguistic symbols, I take “content” to be the cognitive sciences. How are we to account for the roughly synonymous with “meaning.”) The theory must human capacity to create concepts such as electron, also specify how it is that concepts may function in cancer, infinity, galaxy, and wisdom? thought, by virtue of what they combine to form prop- A theory of conceptual development must have three ositions and beliefs, and how they function in inferential components. First, it must characterize the innate rep- processes. TOOC assumes, and ultimately argues for, a resentational repertoire: the representations that are the dual factor theory of concepts. The two factors are some- input to subsequent learning processes. Second, it must times called “reference” and “narrow content.” The con- describe how the initial stock of representations differs tents of our mental representations are partly constituted from the adult conceptual system. Third, it must charac- by the set of entities they refer to. Some theories, (e.g., terize the learning mechanisms that achieve the trans- information semantics) claim that reference is determined formation of the initial into the final state. by causal connections between mental symbols and the The Origin of Concepts (Carey 2009; henceforth entities in their extensions. To the extent this is so, all TOOC) defends three theses. With respect to the initial current psychological theories of concepts are partly on state, contrary to historically important thinkers such as the wrong track: Conceptual content is not exhausted by the British empiricists (Berkeley 1732/1919; Locke prototypes, exemplar representations, or theories of the 1690/1975), Quine (1960) and Piaget (1954), as well as entities in their extensions. The last chapter of TOOC many contemporary scientists, the innate stock of primi- reviews and endorses some of the arguments for infor- tives is not limited to sensory, perceptual, or sensorimotor mation semantics. Contrary to philosophical views that representations; rather, there are also innate conceptual deny that meanings are even partly determined by representations. With respect to developmental change, what’s in the mind, however, TOOC argues that some contrary to what has been written by continuity theorists aspects of inferential role are content determining such as Fodor (1980), Pinker (1994), Macnamara (1986), (narrow content). The challenge for psychologists is speci- and others, conceptual development involves discontinu- fying what aspects of mental representations at least partly ities, resulting in systems of representation that are more determine their meaning, distinguishing these from those powerful than, and sometimes incommensurable with, aspects that are simply what we believe about the rep- those from which they are built. With respect to a learning resented entities. This is sometimes called distinguishing mechanism that achieves conceptual discontinuity, I offer Quinian bootstrapping. SUSAN CAREY, Henry A. Morss, Jr., and Elizabeth 2. Relations between theories of conceptual W. Morss Professor of Psychology at Harvard Univer- development and theories of concepts sity, has written extensively on conceptual develop- ment, with case studies of number representations, intuitive physics, and intuitive biology. Her work was Obviously, our theory of conceptual development must recognized by election to the National Academy of mesh with our theory of concepts. Concepts are mental Sciences in 2002 and the David E. Rumelhart Prize symbols, the units of thought. As with all mental represen- in 2009. tations, a theory of concepts must specify what it is that # Cambridge University Press 2011 0140-525X/11 $40.00 113 Carey: Pre´cis of The Origin of Concepts concepts from conception. One goal of TOOC is to explore middle-distant objects, including representations of causal how understanding of conceptual development requires a and spatial relations among them (TOOC, Ch. 2, 3, and dual factor theory of concepts, and it suggests how we 6); one whose domain is agents, including their goals, com- might approach characterizing which aspects of concep- municative interactions, attentional states, and causal poten- tual role are content determining. Considerations of con- tial (TOOC, Ch. 5 and 6); and the one whose domain is ceptual development constrain a theory of narrow content. numbers, including parallel individuation, analog magnitude TOOC also addresses a gap in the psychological litera- representations of the approximate cardinal values of sets, ture on concepts. In cognitive psychology, concepts are and set-based quantification (TOOC, Ch. 4 and 7). taken to be representations of categories, and category learning is a large topic within the experimental literature 3.1. Conceptual content on concepts and categories. Paradoxically, this literature does not try to account for the origin of the features that Two logically independent and empirically distinct prop- enter into the learning models it explores. erties of core cognition representations lead me to attri- This was not always so. In theorizing about concepts, the bute them conceptual content. First, contrary to British empiricists made accounting for acquisition a empiricist proposals, they cannot be reduced to spatiotem- central concern. They, like many modern thinkers, poral or sensory vocabulary. One cannot capture concepts assumed that all concept learning begins with a primitive such as goal, agent, object,orapproximately 10 in terms of sensory or perceptual vocabulary. That project is doomed primitives such as locations, paths of motion, shapes, and by the simple fact that it is impossible to express the mean- colors. Second, they have a rich, central, conceptual role. ings of most lexical items (e.g., “cause,” “good,” “seven,” The representations in core cognition are centrally acces- “gold,” “dog”) in terms of perceptual features. In response, sible, represented in working memory models, and some theorists posit a rich stock of developmental primi- support decision and control mechanisms leading to tives, assuming that the definitional primitives that struc- action such as reaching. For example, infants make a ture the adult conceptual repertoire, and the working memory model of the individual crackers in developmental primitives over which hypothesis testing each of two buckets and guide their choice of which is performed early in development, are one and the same bucket to crawl to from quantitative computations using set. A moment’s reflection shows that definitional primi- those models. A variety of quantitative computations are tives are poor candidates for developmental primitives. defined over working memory representations of sets of For example, the definition of gold within modern chem- objects. Preverbal infants can sum continuous quantities istry might be element with atomic number 79. Clearly, or compare models on the basis of one-to-one correspon- the primitives element and atomic number are not innate dence and categorically distinguish singletons from sets of conceptual features. Or take the features that determine multiple individuals. Moreover, young infants represent the prototype structure of bird concepts (flies, lays eggs, objects relative to the goals of agents, and infants’ rep- has wings, nests in trees, has a beak, sings, etc.). Subjects resentations of physical causality are constrained by their provide distinctive values for such features when asked conceptualization of the participants in a given interaction to list the features of birds, and overlap in terms of these (as agents capable of self-generated motion or as inert same features predicts prototypicality within the category objects). Thus, the conceptual status of the output of a bird. That is, this feature space definitely underlies adult given core cognition system is confirmed by its conceptual prototypicality structure. Yet these features are not interrelations