The Dynamical Hypothesis in Cognitive Science: A Review Essay of Mind As Motion

Abstract

Sometimes it is hard to know precisely what to think about the Dynamical Hypothesis (hereafter, DH), the new kid on the block in cognitive science and described succinctly by the slogan "cognitive agents are dynamical systems" (Van Gelder, 1998). Is the DH a radically new approach to understanding human cognition? (No.) Is it providing deep insights that traditional symbolic artificial intelligence overlooked? (Certainly.) Is it providing deep insights that recurrent connectionist models, circa 1990, had overlooked? (Probably not.) Is time, as instantiated in the DH, necessary to our understanding of cognition? (Certainly.) Is time, as instantiated in the DH, sufficient for understanding cognition? (Certainly not.) The DH is often touted as being a revolutionary alternative to the traditional Physical Symbol System Hypothesis (PSSH, renamed in Mind As Motion, the Computational Hypothesis) (Newell and Simon, 1976) that was the bedrock of artificial intelligence for 25 years. We disagree. First, as pointed out by the authors themselves, the use of dynamics as a framework to comprehend the brain and cognition is not new. In the early 1950’s, for example, W. Ross Ashby wrote a wonderful little treatise called Design for a Brain (1952) based on the recurrent, dynamical nature of the brain. The whole field of cybernetics (Wiener, 1948), developed during the late 1940’s, was also deeply concerned with feedback and stability in complex evolving systems. The explicit goal of these authors and others was to develop a general framework within which biological and cognitive systems could be studied and understood. These efforts, while vision in scope, did not bear fruit, in part because the systems they hoped to understand – in particular, human brain function and cognitive activities – were extraordinarily complex and there were no realistic means of empirically testing the ‘hypotheses’ generated by this approach to cognition.