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

thinking was logic, then thinking machines—machines that could do logic—existed
in the late nineteenth century.
The logic machines of the nineteenth century were, in fact, quite limited in ability,
as we see later in this chapter. However, they were soon replaced by much more
powerful devices. In the first half of the twentieth century, the basic theory of a general
computing mechanism had been laid out in Alan Turing’s account of his universal
machine (Hodges, 1983; Turing, 1936). The universal machine was a device
that “could simulate the work done by any machine. . . . It would be a machine to
do everything, which was enough to give anyone pause for thought” (Hodges, 1983,
p. 104). The theory was converted into working universal machines—electronic
computers—by the middle of the twentieth century (Goldstine, 1993; Reid, 2001;
Williams, 1997).
The invention of the electronic computer made logicism practical. The computer’s
general ability to manipulate symbols made the attainment of machine intelligence
seem plausible to many, and inevitable to some (Turing, 1950). Logicism was
validated every time a computer accomplished some new task that had been presumed
to be the exclusive domain of human intelligence (Kurzweil, 1990, 1999). The
pioneers of cognitive science made some bold claims and some aggressive predictions
(McCorduck, 1979): in 1956, Herbert Simon announced to a mathematical modelling
class that “Over Christmas Allen Newell and I invented a thinking machine”
(McCorduck, 1979, p. 116). It was predicted that by the late 1960s most theories in
psychology would be expressed as computer programs (Simon & Newell, 1958).
The means by which computers accomplished complex information processing
tasks inspired theories about the nature of human thought. The basic workings
of computers became, at the very least, a metaphor for the architecture of human
cognition. This metaphor is evident in philosophy in the early 1940s (Craik, 1943).
My hypothesis then is that thought models, or parallels, reality—that its essential
feature is not ‘the mind,’ ‘the self,’ ‘sense data’ nor ‘propositions,’ but is symbolism,
and that this symbolism is largely of the same kind which is familiar to us in
mechanical devices which aid thought and calculation. (Craik, 1943, p. 57)
Importantly, many modern cognitive scientists do not see the relationship between
cognition and computers as being merely metaphorical (Pylyshyn, 1979a, p. 435):
“For me, the notion of computation stands in the same relation to cognition as
geometry does to mechanics: It is not a metaphor but part of a literal description of
cognitive activity.”
Computers are special devices in another sense: in order to explain how they
work, one must look at them from several different perspectives. Each perspective
requires a radically different vocabulary to describe what computers do. When cognitive
science assumes that cognition is computation, it also assumes that human
cognition must be explained using multiple vocabularies.
22 Chapter 2