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

accounts (Broadbent, 1985; Rumelhart & McClelland, 1985). Similarly, an algorithmic
account of internal planning would be quite different from an embodied
account of controlled action, or of scaffolded, cognition. In spite of such technical
differences, though, it would be difficult to claim that one approach to cognitive science
provides procedural accounts, while another does not. All three approaches to
cognitive science are motivated to investigate at the algorithmic level.
At Marr’s (1982) computational level, cognitive scientists wish to determine the
nature of the information processing problems being solved by agents. Answering
these questions usually requires developing proofs in some formal language. Again,
all three approaches to cognitive science are well versed in posing computationallevel
questions. The differences between them are reflected in the formal language
used to explore answers to these questions. Classical cognitive science often
appeals to some form of propositional logic (Chomsky, 1959a; McCawley, 1981;
Wexler & Culicover, 1980), the behaviour of connectionist networks lends itself to
being described in terms of statistical mechanics (Amit, 1989; Grossberg, 1988;
Smolensky, 1988; Smolensky & Legendre, 2006), and embodied cognitive scientists
have a preference for dynamical systems theory (Clark, 1997; Port & van Gelder,
1995b; Shapiro, 2011).
Marr’s (1982) tri-level hypothesis is only one example of exploring cognition at
multiple levels. Precursors of Marr’s approach can be found in core writings that
appeared fairly early in cognitive science’s modern history. For instance, philosopher
Jerry Fodor (1968b) noted that one cannot establish any kind of equivalence between
the behaviour of an organism and the behaviour of a simulation without first specifying
a level of description that places the comparison in a particular context.
Marr (1982) himself noted that an even stronger parallel exists between the
tri-level hypothesis and Chomsky’s (1965) approach to language. To begin with,
Chomsky’s notion of an innate and universal grammar, as well as his idea of a
“language organ” or a “faculty of language,” reflect a materialist view of language.
Chomsky clearly expects that language can be investigated at the implementational
level. The language faculty is due “to millions of years of evolution or to principles of
neural organization that may be even more deeply grounded in physical law” (p. 59).
Similarly, “the study of innate mechanisms leads us to universal grammar, but also,
of course, to investigation of the biologically determined principles that underlie
language use” (Chomsky, 1980, p. 206).
Marr’s (1982) algorithmic level is mirrored by Chomsky’s (1965) concept of
linguistic performance. Linguistic performance is algorithmic in the sense that a
performance theory should account for “the actual use of language in concrete situations”
(Chomsky, 1965, p. 4). The psychology of language can be construed as being
primarily concerned with providing theories of performance (Chomsky, 1980). That
is, psychology’s “concern is the processes of production, interpretation, and the like,
350 Chapter 7