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

symbols. However, as connectionism matured, it was necessary for its researchers
to spell out the details of the alternative algorithms embodied in their networks
(Dawson, 2004). If these algorithms could not be extracted from networks, then
“connectionist networks should not be viewed as theories of human cognitive functions,
or as simulations of theories, or even as demonstrations of specific theoretical
points” (McCloskey, 1991, p. 387). In response to such criticisms, connectionist cognitive
scientists have developed a number of techniques for recovering algorithms
from their networks (Berkeley et al., 1995; Dawson, 2004, 2005; Gallant, 1993; Hanson
& Burr, 1990; Hinton, 1986; Moorhead, Haig, & Clement, 1989; Omlin & Giles, 1996).
What are the elements of connectionism, and how do they relate to cognitive
science in general and to classical cognitive science in particular? The purpose of
the remainder of this chapter is to explore the ideas of connectionist cognitive science
in more detail.
4.2 Associations
Classical cognitive science has been profoundly influenced by seventeenth-century
Cartesian philosophy (Descartes, 1996, 2006). The Cartesian view that thinking is
equivalent to performing mental logic—that it is a mental discourse of computation
or calculation (Hobbes, 1967)—has inspired the logicism that serves as the foundation
of the classical approach. Fundamental classical notions, such as the assumption
that cognition is the result of rule-governed symbol manipulation (Craik, 1943)
or that innate knowledge is required to solve problems of underdetermination
(Chomsky, 1965, 1966), have resulted in the classical being viewed as a newer variant
of Cartesian rationalism (Paivio, 1986). One key classical departure from Descartes
is its rejection of dualism. Classical cognitive science has appealed to recursive rules
to permit finite devices to generate an infinite variety of potential behaviour.
Classical cognitive science is the modern rationalism, and one of the key ideas
that it employs is recursion. Connectionist cognitive science has very different
philosophical roots. Connectionism is the modern form of empiricist philosophy
(Berkeley, 1710; Hume, 1952; Locke, 1977), where knowledge is not innate, but is
instead provided by sensing the world. “No man’s knowledge here can go beyond
his experience” (Locke, 1977, p. 83). If recursion is fundamental to the classical
approach’s rationalism, then what notion is fundamental to connectionism’s empiricism?
The key idea is association: different ideas can be linked together, so that if
one arises, then the association between them causes the other to arise as well.
For centuries, philosophers and psychologists have studied associations empirically,
through introspection (Warren, 1921). These introspections have revealed
the existence of sequences of thought that occur during thinking. Associationism
attempted to determine the laws that would account for these sequences of thought.
Elements of Connectionist Cognitive Science 133