Cognitive Modularity, Biological Modularity, and Evolvability

Cognitive Modularity, Biological Modularity, and Evolvability

Cognitive Modularity, Biological Modularity, and Evolvability Claudia Lorena Garcıa´ Abstract Instituto de Investigaciones Filosoficas,´ Universidad Nacional I examine an argument that has recently appeared in the cog- Autonoma´ de Mexico´ nitive science literature in favor of thinking that the mind is [email protected] mostly (or even exclusively) composed of Fodorian-type cog- nitive modules; an argument that concludes that a mind that is massively composed of classical cognitive mechanisms that are cognitively modular is more evolvable than a mind that is not cognitively modular (or that is scarcely cognitively modu- lar), since a cognitive mechanism that is cognitively modular is likely to be biologically modular, and biologically modular characters are more evolvable. I argue that the notion of cog- nitive modularity needed to make this argument plausible will have to be understood (at least partly) in terms of the biologi- cal notion of variational independence, as follows: a cognitive feature is cognitively modular only if few or no other morpho- logical changes (cognitive and not) are significantly correlated with variations of that feature arising in members of the rele- vant population as a result of ontogeny. I also argue that most of the connotations contained in a cluster of notions of classical cognitive modularity (e.g., domain specificity, encapsulation, functional specialization, etc.) are, as far as we know, irrele- vant to the argument, and that only the presence of selective impairments—also known as cognitive dissociations—can be considered as strong indicators of the type of modularity that genuinely enhances evolvability. Keywords biological modularity, cognitive evolvability, cognitive modu- larity, double dissociations, massive modularity September 15, 2006; accepted 62 Biological Theory 2(1) 2007, 62–73. c 2007 Konrad Lorenz Institute for Evolution and Cognition Research Claudia Lorena Garcıa´ There is an argument that has recently been deployed in fa- (a) it is domain-specific; i.e., it admits inputs only from vor of thinking that the mind is mostly (or even exclusively) a certain informational domain; composed of cognitive modules; an argument that makes use (b) its operation is mandatory since its operation (or its of some ideas and concepts of evolutionary and of develop- ceasing to operate) does not depend upon the subject mental biology. In a nutshell, the argument concludes that a deciding or wanting the mechanism to operate (or to mind that is massively composed of cognitive mechanisms cease to operate); that are cognitively modular (henceforth, c-modular) is more (c) other parts of the mind have limited access to the evolvable than a mind that is not c-modular (or that is scarcely representations or information that the mechanism is c-modular), since a cognitive mechanism that is c-modular is using to compute its output; likely to be biologically modular (henceforth, b-modular), and (d) the mechanism operates very fast; b-modular characters are more evolvable (e.g., Sperber 2001; (e) it is informationally encapsulated since its has no Carruthers 2005). In evolutionary biology, the evolvability of (or limited) access to most of the information that is a character in an organism is understood as the “organism’s accesible to other parts of the mind; capacity to facilitate the generation of non-lethal selectable (f) it has “shallow” outputs that are informationally poor; phenotypic variation from random mutation” with respect to (g) it is associated to a fixed neural architecture; that character (Gerhart and Kirschner 2003). (h) it exhibits specific breakdown patterns; and Here I will argue that the notion of cognitive modular- (i) it is innate. ity needed to make this argument plausible will have to be understood in terms of the biological notion of variational in- Fodor thought that, in some ways, he was following an older dependence; that is, it will have to be understood in such a way school of thought in psychology, which fell into disrepute for that a cognitive feature is c-modular only if few or no other a long time and which he dubbed “vertical faculty psychol- morphological changes (cognitive and not) are significantly ogy,” initiated by Franz Joseph Gall (1758–1828), and which, correlated with variations of that feature arising in members of according to Fodor, defended that there is no such a thing as a the relevant population as a result of ontogeny.1 Furthermore, general faculty of understanding; rather, “the intellectual ap- I will show that at present there are no reasons—either empiri- titudes . are distinguished by their subject matter” (Fodor cal or otherwise—to think that the connotations contained in a 1983: 15)—or, to put it in Fodor’s terminology, each apti- cluster of notions of cognitive modularity widely accepted in tude is subserved by a distinct, domain-specific faculty. Fodor some of the mainstream currents of thought in classical cogni- thought that his proposal that our sensory capacities and at tive science, are relevant to the argument—with one possible least some aspects of the linguistic capacity are modular, is exception. In order to argue for this, I will have to examine the partially within the spirit of Gall’s views. question as to whether there are any strong theoretical con- But other authors after Fodor have emphasized, rejected nections between (1) those connotations, and (2) notions of or added other characteristics as interestingly associated to modularity accepted in biology, specially in evolutionary and c-modularity; they also have differed from him in the extent to in developmental biology, that are thought to be most relevant which they think that the mind is modular. Those authors who to arguments to the effect that biological modularity enhances think that the mind is mostly (or even exclusively) c-modular evolvability. are called “massive modularists.” For example, Cosmides and Tooby (1997: 80, 92, 93) are massive modularists who empha- size domain specificity, and add functional specialization and genetic specification as necessary conditions for c-modularity, 1. Cognitive Modularity while they tend reject or ignore the rest. Annette Karmiloff- In the contemporary literature in evolutionary psychology, Smith is probably not inclined to be a massive modularist, cognitive ethology, developmental psychology, cognitive neu- and thinks that domain specificity, mandatoriness, encapsu- ropsychology, and other cognitive disciplines, one can often lation and speed are necessary conditions of c-modularity find a discussion as to whether—and how many, and in what (Karmiloff-Smith 1992: 4–6), while rejecting that innateness sense—the cognitive mechanisms that constitute the minds of is a necessary condition because she thinks that certain abilities animals and of humans are c-modular. It is virtually true, how- can become modularized as a result of learning. Additionally, ever, that no two authors in these cognitive disciplines handle although Sperber (1994: 48), a massive modularist, used to the same notion of cognitive modularity. think that domain specificity, encapsulation, and genetic spec- The most influential notion of c-modularity was initially ification were necessary conditions of c-modularity, recently introduced by Jerry Fodor (1983), who proposed that a classi- he seems more inclined to reject domain specificity and to think cal computational mechanism is c-modular when (and to the that encapsulation and functional specificity (or specialization) extent that) it has one or more of the following characteristics:2 are the only key elements required to talk about c-modularity Biological Theory 2(1) 2007 63 Cognitive Modularity, Biological Modularity, and Evolvability in the cognitive sciences (Sperber 2001). Carruthers (2005), changeable genetic information” (Riedl 1977: 360). He pro- another massive modularist, agrees that domain specificity is posed a theory of “genome systemization,” which “demands not a necessary condition of c-modularity, while claiming that feedback loops of cause and effect both from the genome to encapsulation, independent operation, and functional special- the phenome and in the reverse direction. Such feedbacks can ization are some of the necessary conditions. accelerate adaptation only in the direction in which gene in- Here I will not examine the debates concerning which teractions have imitated the patters of functional interactions characteristics one should include in a theoretically interesting in the phenome” (Riedl 1977: 361). and useful notion of c-modularity.3 Instead, I will examine the On the other hand, Gould (1977) suggested that dissocia- question as to what notion of c-modularity is needed to make ble developmental processes are necessary in order for hete- plausible the aforementioned argument for the view that the rochronic change to take place; that is, change in the relative mind is mostly c-modular. rates or timing of development of different cell lines. Later, Now, as we have seen so far, the consensus among Bonner (1988: 174) coined the concept of gene net, which massive modularists tends to be that one should understand stands for “a grouping of a network of gene actions and their c-modularity in terms of one or more of the following char- products into descrete units during the course of development.” acteristics: encapsulation, domain specificity, functional spe- He thought that the existence of these nets during ontogeny— cialization, innateness, and the presence of specific patterns of especially the ontogeny of complex organisms—is what makes cognitive breakdown.4 Thus one should ask the question as to possible both the success of the process of development as well whether massive modularists are understanding c-modularity as constituting an explanation as to how “complex developing in a way that is conducive to making plausible the argument organisms can change in evolution” (175). As we shall see, for the evolvability of c-modules—an argument that, accord- Wagner and others have in some form or another taken these ing to at least some of them, is key to upholding the massive ideas—but especially the idea of gene nets—in order to for- modularity hypothesis (Sperber 2001; Carruthers 2005).

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