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Modularity as an issue for cognitive science
Cognition, 10 (1481) 231-242 @ Elsevier Sequoja %A., Lausanne - Printed in The Netherlands
241
Modularity as an issue for cognitive scietmce DANIEL
N. OSHcfGON
Massachusetts Institl
*
te of Technology
Several decades of research within disciplines now counted among the cognitive sciences has prepared a serious issue for investigation. The issue concerns the degree of modular structure exhibited by the system of faculties comprising the human intellectual repertoire. To clarify the modularity question it helps to construe faculties as putative kinds; so construed, faculties are maximal collections of psychologi,d. *_I1 p-recesses and structures that function in accord with a relatively small set of interlocking and explanatory principles. This view of faculties harbors two potential complexities that may be mentioned here and then put aside. First, it is commonplace to observe that mental process :s and structures may be manifest at several distinct Ievels of ‘reduction’, including the neurophysiological, the psychological, and the functional; so it is possible that processes or structur-zs grouped together at one level may fall info different faculties at another. In the latter ctise, it will be necessary to relativize one’s claims about faculties to particular reductive. levels.’ Second, it is logically possible for there to be no faculties at all in the desired sense. That is, the human nervolls system may offer up no coherent class of processes or structures susceptible to explanatory analysis by a relatively small set of principles. It has thus been a nontrivial achievement of the cognitive sciences to uncover a surprising degree of coherence in several areas of human ability, in particular, in language and vision; whatever prin-, ciples explain the regularities so far uncovered, it is plausible to assume that one or more faculties are implicated. These qualifications aside, the modularity question may be stated in gross form as follows; How many human faculties are there? An answer to this latter question will rest on answers to more refined questions concerning the principles governing various processes, structures, and functions. Faculties may be individuated on the basis of the incompatibility of the principles governing each. To clarify, let C1 and C2 be two classes of processes and *Reprintrequests should be sent to D. Qsherson, 2OC-124 (DSRE), MIT, Cambridge, Mass., 02139, U.S.A. ’ See Osherson and Wasow (1976) for discussion. Anothr ; potential complication: The acquisitional mechanisms for various faculties need nott, by logic, partition themselves in the same fashion as the acquired faculties, although one would susplect that a congruence obtains in fact.
242
DankfiX Osheron
structures that conform to two sets of interlocking and explanatory principles, P1 and P2, respectively. If the properties of C1 can be proved hot to be deducible from Pz, and likewise for C2 and P, , then distinct faculties are (provisionally) revealed. Note that to establish a claim for distinct faculties, it is not sufficient L- exhibit classes of processes or structures for which distinct explanatory principles exist; for, although the theories may be distinct, they might nonetheless be equivalent in the sense that it may be possible to reformulate one or both as a more general account of both kinds of phenomena. It is thus required .to provide a formal argument that processes and structures governed by one set of principles cannot be governed by the other. The next ten years of research may well see definite, if limited, progress in answering the modularity question. Explanatory principles are beginning to emerge in several subfields of linguistics, in visual pattern recognition (as in the work of Ullman (1979)), and in inductive logic (as in the work of Horwith (1981)). AS theories in these and other areas are articulated more and more precisely, relevant principles can be compared in the manner suggested above. No doubt initial comparisons will reveal a cloudy picture of partial overlap and independence among the several subsystems comprising putative faculties. With explicit claims about modularity in hand, however, we can hope for steady clarification. Of the several inquiries that might be undertaken by cognitive scientists over the next decade, investigation of the modularity issue seems to me to be among the most feasible and intrinsically interesting. References Horwich, Paul 11981) fiobubility and Evidence,Cambalclge. Cambridge University Press. @*herson, D-niel and Wasow, Thomas (1976) Species specificity and task specificity in the study of knguage: a methodological note. Cog., 4, 203-214. Ulhnan, Shimon (1979) TheInterpret&ionof VisualMotion. Cambridge, MIT Press.
241
Modularity as an issue for cognitive scietmce DANIEL
N. OSHcfGON
Massachusetts Institl
*
te of Technology
Several decades of research within disciplines now counted among the cognitive sciences has prepared a serious issue for investigation. The issue concerns the degree of modular structure exhibited by the system of faculties comprising the human intellectual repertoire. To clarify the modularity question it helps to construe faculties as putative kinds; so construed, faculties are maximal collections of psychologi,d. *_I1 p-recesses and structures that function in accord with a relatively small set of interlocking and explanatory principles. This view of faculties harbors two potential complexities that may be mentioned here and then put aside. First, it is commonplace to observe that mental process :s and structures may be manifest at several distinct Ievels of ‘reduction’, including the neurophysiological, the psychological, and the functional; so it is possible that processes or structur-zs grouped together at one level may fall info different faculties at another. In the latter ctise, it will be necessary to relativize one’s claims about faculties to particular reductive. levels.’ Second, it is logically possible for there to be no faculties at all in the desired sense. That is, the human nervolls system may offer up no coherent class of processes or structures susceptible to explanatory analysis by a relatively small set of principles. It has thus been a nontrivial achievement of the cognitive sciences to uncover a surprising degree of coherence in several areas of human ability, in particular, in language and vision; whatever prin-, ciples explain the regularities so far uncovered, it is plausible to assume that one or more faculties are implicated. These qualifications aside, the modularity question may be stated in gross form as follows; How many human faculties are there? An answer to this latter question will rest on answers to more refined questions concerning the principles governing various processes, structures, and functions. Faculties may be individuated on the basis of the incompatibility of the principles governing each. To clarify, let C1 and C2 be two classes of processes and *Reprintrequests should be sent to D. Qsherson, 2OC-124 (DSRE), MIT, Cambridge, Mass., 02139, U.S.A. ’ See Osherson and Wasow (1976) for discussion. Anothr ; potential complication: The acquisitional mechanisms for various faculties need nott, by logic, partition themselves in the same fashion as the acquired faculties, although one would susplect that a congruence obtains in fact.
242
DankfiX Osheron
structures that conform to two sets of interlocking and explanatory principles, P1 and P2, respectively. If the properties of C1 can be proved hot to be deducible from Pz, and likewise for C2 and P, , then distinct faculties are (provisionally) revealed. Note that to establish a claim for distinct faculties, it is not sufficient L- exhibit classes of processes or structures for which distinct explanatory principles exist; for, although the theories may be distinct, they might nonetheless be equivalent in the sense that it may be possible to reformulate one or both as a more general account of both kinds of phenomena. It is thus required .to provide a formal argument that processes and structures governed by one set of principles cannot be governed by the other. The next ten years of research may well see definite, if limited, progress in answering the modularity question. Explanatory principles are beginning to emerge in several subfields of linguistics, in visual pattern recognition (as in the work of Ullman (1979)), and in inductive logic (as in the work of Horwith (1981)). AS theories in these and other areas are articulated more and more precisely, relevant principles can be compared in the manner suggested above. No doubt initial comparisons will reveal a cloudy picture of partial overlap and independence among the several subsystems comprising putative faculties. With explicit claims about modularity in hand, however, we can hope for steady clarification. Of the several inquiries that might be undertaken by cognitive scientists over the next decade, investigation of the modularity issue seems to me to be among the most feasible and intrinsically interesting. References Horwich, Paul 11981) fiobubility and Evidence,Cambalclge. Cambridge University Press. @*herson, D-niel and Wasow, Thomas (1976) Species specificity and task specificity in the study of knguage: a methodological note. Cog., 4, 203-214. Ulhnan, Shimon (1979) TheInterpret&ionof VisualMotion. Cambridge, MIT Press.