Darwinian Functionalism: A Cognitive Science Paradigm

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Anderson (1990) has argued that cognitive science is in need of a shift in emphasis away from modeling mental architecture in favor of an evolutionary or "adaptionist" perspective on human cognition. The implication is that cognitive psychology's neostructuralist research paradigm is giving way to a neofunctionalist one. It is also a signal that cognitivism has progressed through what Kuhn (1970) labeled normal science and is currently experiencing a crisis of nonconfidence. A shift in emphasis is necessary because cognitivism is in danger of degenerating into a kind of mentalism where unconstrained model building leads to an ever increasing need for new models to account for the anomalies resulting from new data (Amsel, 1989; Knight, 1990). Ultimately an unrestrained emphasis on explanation will overwhelm a discipline with more answers than there were questions to begin with. What is needed is not more answers in the form of more models, but better questions.

If psychological theory is fragmented and incoherent it is because we have not been asking good (well-formed) questions. We have not been asking good questions because we have not had a theoretical basis from which to deduce expectancies. A return to functionalism, in the form of evolutionary psychology, has the potential for providing a hypothetico-deductive theoretical base that achieves prediction, explanation through meaningful organization, and in addition has an aesthetic quality that has historically characterized successful theorizing in science. What follows is an exposition of Darwinian functionalism as the elusive paradigm required to achieve Thomas Kuhn's criterion for a science--to achieve psychology as science.

Arnold Buss (1973) suggested that advances in genetics, evolutionary theory, and ethology had made possible a comprehensive theory which for the first time could effectively organize all of psychology around it. The missing ingredient seems to have been supplied by cognitive science with its unique perspective on the brain as a thinking machine. The functioning of cognitive mechanisms supplied the common ground for rapprochement. As James (1890) said in his Principles of Psychology, "the only thing which psychology has a right to postulate at the outset is the fact of thinking itself". The last 20 years of cognitive science research have been spent developing a viable language for the description of mental modeling. Cosmides and Tooby (1987) were in a position to declare that, "there is emerging a new method, here called evolutionary psychology, which is made possible by the simultaneous maturation of evolutionary biology, paleoanthropology, and cognitive psychology".

Darwinian Functionalism

Even if all the hawks in the world were to vanish, their image would still sleep in the soul of the chick. Joseph Campbell.

At the heart of evolutionary psychology is the question of function. It makes little sense to question an organism's structure without a consideration of how it functions. In like manner a consideration of how something functions can only be understood within the context of what it was designed to do. The functionalism of James and Dewey emphasized the importance of defining something in terms of what it does. Darwinian functionalism goes a step further and recognizes the inseparability of function and design. Understanding design makes it possible to ask meaningful questions regarding function and guides the study of structure. The internal mechanics of a telephone and the ways in which it can be used are meaningless apart from the knowledge that humans are a socially intelligent species with a need for information. The logical deduction from this knowledge is that an enhanced ability to communicate will be selected for and as a consequence will form an integral part of any social ecology.

Evolutionary design provides the knowledge base from which theoretical constructs, in the form of cognitive mechanisms, can be deduced (Anderson, 1990; Cosmides & Tooby, 1987). It is for this reason that the first premise of Darwinian functionalism is that behavior is the product of evolved cognitive mechanisms. As numerous others have pointed out it makes little sense to speak of evolved behavior. Behavior did not evolve any more than vision evolved. The brain and the eye have evolved and vision is the consequence. Similarly, behavior must be conceptualized as the result of evolved cognitive mechanisms in the functioning brain. Whether we refer to these mechanisms as mental organs (Chomsky, 1980), stimulus analyzers (Mackintosh, 1977), stimulus detectors (Eibl-Eibesfeldt, 1989), psychological mechanisms (Cosmides & Tooby, 1987), P-cognitions (Margolis, 1987), or Kant's a priori (innate) categories of thought (Hergenhahn, 1986), the emphasis is on the filtering of information through these devices for the purpose of structuring perception (Gregory, 1983).

A theory is an algorithmic description of how cognitive mechanisms function. To build this theory requires an understanding of the evolution of cognitive mechanisms as adaptations--adaptations reflecting the demand characteristics of particular physical and social ecologies. Meaningful questions in the form of postulates or hypotheses can be deduced from the theory and translated into the if/then logical consequences associated with experimentation. A particularly good example of this process is provided by social exchange theory (Cosmides, 1989; Cosmides & Tooby, 1989b) where knowledge of the constraints inherent in a paleolithic social environment revealed that humans must have evolved unique abilities to process information if they were to be successful in solving their adaptive problems and that the design features of these evolved cognitive mechanisms must operate on a cost-benefit representation of the exchange interaction and be able to perform an inferential procedure which enhances the probability of detecting cheating on a social contract. From the algorithmic description of the cognitive mechanisms which govern human reasoning about social exchange, Cosmides (1989) designed an elaborate series of experiments to test the sometimes anomalous predictions regarding how humans use logic to solve problems. The interested reader is referred to this theory and the accompanying experiments as a model for research which exemplifies the principles outlined in this article and inherent in Darwinian functionalism.

As a paradigm for research Darwinian functionalism can be conceptualized as a five phase process: (1) naturalistic observation, (2) prediction of evolutionary contingencies, (3) hypothetico-deductive …