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

physical symbol system hypothesis: “the necessary and sufficient condition for a
physical system to exhibit general intelligent action is that it be a physical symbol
system” (Newell, 1980, p. 170). By necessary, Newell meant that if an artifact exhibits
general intelligence, then it must be an instance of a physical symbol system. By
sufficient, Newell claimed that any device that is a physical symbol system can be
configured to exhibit general intelligent action—that is, he claimed the plausibility
of machine intelligence, a position that Descartes denied.
What did Newell (1980) mean by general intelligent action? He meant,
the same scope of intelligence seen in human action: that in real situations behavior
appropriate to the ends of the system and adaptive to the demands of the environment
can occur, within some physical limits. (Newell, 1980, p. 170)
In other words, human cognition must be the product of a physical symbol system.
Thus human cognition must be explained by adopting all of the different levels of
investigation that were described in Chapter 2.
3.7 Componentiality, Computability, and Cognition
In 1840, computer pioneer Charles Babbage displayed a portrait of loom inventor
Joseph Marie Jacquard for the guests at the famous parties in his home (Essinger,
2004). The small portrait was incredibly detailed. Babbage took great pleasure in
the fact that most people who first saw the portrait mistook it to be an engraving. It
was instead an intricate fabric woven on a loom of the type that Jacquard himself
invented.
The amazing detail of the portrait was the result of its being composed of 24,000
rows of weaving. In a Jacquard loom, punched cards determined which threads
would be raised (and therefore visible) for each row in the fabric. Each thread in the
loom was attached to a rod; a hole in the punched card permitted a rod to move,
raising its thread. The complexity of the Jacquard portrait was produced by using
24,000 punched cards to control the loom.
Though Jacquard’s portrait was impressively complicated, the process used to
create it was mechanical, simple, repetitive—and local. With each pass of the loom’s
shuttle, weaving a set of threads together into a row, the only function of a punched
card was to manipulate rods. In other words, each punched card only controlled
small components of the overall pattern. While the entire set of punched cards represented
the total pattern to be produced, this total pattern was neither contained
in, nor required by, an individual punched card as it manipulated the loom’s rods.
The portrait of Jacquard was a global pattern that emerged from a long sequence of
simple, local operations on the pattern’s components.
78 Chapter 3