Mind, Body, World- Foundations of Cognitive Science, 2013a

3.10 A Classical Architecture for Cognition
The physical symbol system hypothesis defines classical cognitive science. This
school of thought can be thought of as the modern derivative of Cartesian philosophy.
It views cognition as computation, where computation is the rule-governed
manipulation of symbols. Thus thinking and reasoning are viewed as the result of
performing something akin to logical or mathematical inference. A great deal of
this computational apparatus must be innate.
However, classical cognitive science crucially departs from Cartesian philosophy
by abandoning dualism. Classical cognitive science instead adopts a materialist
position that mechanizes the mind. The technical notion of computation is the
application of a finite set of recursive rules to a finite set of primitives to evolve a
set of finite symbolic structures or expressions. This technical definition of computation
is beyond the capabilities of some devices, such as finite state automata,
but can be accomplished by universal machines such as Turing machines or electronic
computers. The claim that cognition is the product of a device that belongs
to the same class of artifacts such as Turing machines or digital computers is the
essence of the physical symbol system hypothesis, and the foundation of classical
cognitive science.
Since the invention of the digital computer, scholars have seriously considered
the possibility that the brain was also a computer of this type. For instance, the
all-or-none nature of a neuron’s action potential has suggested that the brain is
also digital in nature (von Neumann, 1958). However, von Neumann went on to
claim that the small size and slow speed of neurons, in comparison to electronic
components, suggested that the brain would have a different architecture than an
electronic computer. For instance, von Neumann speculated that the brain’s architecture
would be far more parallel in nature.
Von Neumann’s (1958) speculations raise another key issue. While classical
cognitive scientists are confident that brains belong to the same class as Turing
machines and digital computers (i.e., all are physical symbol systems), they do not
expect the brain to have the same architecture. If the brain is a physical symbol
system, then what might its architecture be like?
Many classical cognitive scientists believe that the architecture of cognition
is some kind of production system. The model of production system architecture
was invented by Newell and Simon (Newell, 1973; Newell & Simon, 1961, 1972)
and has been used to simulate many psychological phenomena (Anderson, 1983;
Anderson et al., 2004; Anderson & Matessa, 1997; Meyer et al. 2001; Meyer & Kieras,
1997a, 1997b; Newell, 1990; Newell & Simon, 1972). Production systems have a
number of interesting properties, including an interesting mix of parallel and serial
processing.
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