Natural and Artificial Cognition: On the Proper Place of Reason Abstract
We explore the psychological foundations of Logic and Artificial Intelligence, touching on representation, categorisation, heuristics, consciousness, and emotion. Specifically, we challenge Dennett’s view of the brain as a syntactic engine that is limited to processing symbols according to their structural properties. We show that cognitive psychology and neurobiology support a dual-process model in which one form of cognition is essentially semantical and differs in important ways from the operation of a syntactic engine. The dual-process model illuminates two important events in Logic and Artificial Intelligence, namely the emergence of non-monotonicity and of embodiment, events that changed the traditional paradigms of ‘Logic = the study of deductive inference’ and ‘Symbolic AI’.
Daniel Dennett articulates a widely-shared view when he asserts:
…brains are just very complicated physical organs; whatever they react to must be some physical change or difference in the stimuli they encounter. In short, as physical mechanisms they can only be syntatic[sic]engines, responding only to structural or formal properties. According to the traditional distinction in linguistics, a sentence’s form or syntax is one thing and its meaning or semantics is another. Now how does the brain manage to get semantics from syntax? It couldn’t. (Dennett 1984 p28)
Few philosophers of mind have been as influential in recent times as Dennett. Nevertheless, our purpose is to demolish his claim. We shall accomplish this in two steps. First, we show that a key inference in his argument does not follow. Second, we provide an alternative view, based on the convergence of evidence from several subdisciplines of cognitive science.
Dennett’s argument has a weak link. We may accept his premiss, namely that brains, being physical organs, react only to physical changes in stimuli. But this does not oblige us to accept the conclusion, namely that brains can respond only to the form of a sentence. The error lies in Dennett’s rejection of non-symbolic mental representations. If it be granted that the brain processes representations other than symbols (as well as symbols, of course), then it can no longer be maintained that a response to a structural property of such a representation is a response to the form of a sentence. The remainder of this paper is devoted to the development of a model of cognition in which non-symbolic representations play a vital role. As a result, a new perspective will be gained on recent trends in Artificial Intelligence.