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

physical scene that is being viewed.”
Vera and Simon (1993) adopted this representational interpretation of affordances
because, by their definition, an affordance designates some worldly state of
affairs and must therefore be symbolic. As a result, Vera and Simon redefined the
sense-act links of direct perception as indirect sense-think-act processing. To them,
affordances were symbols informed by senses, and actions were the consequence of
the presence of motor representations. Similar accounts of affordances have been
proposed in the more recent literature (Sahin et al., 2007).
While Vera and Simon’s (1993) use of designation to provide a liberal definition
of symbol permits a representational account of anti-representational theories,
it does so at the expense of neglecting core assumptions of classical models. In
particular, other leading classical cognitive scientists adopt a much more stringent
definition of symbol that prevents, for instance, direct perception to be viewed as
a classical theory. Pylyshyn has argued that cognitive scientists must adopt a cognitive
vocabulary in their theories (Pylyshyn, 1984). Such a vocabulary captures
regularities by appealing to the contents of representational states, as illustrated
in adopting the intentional stance (Dennett, 1987) or in employing theory-theory
(Gopnik & Meltzoff, 1997; Gopnik & Wellman, 1992).
Importantly, for Pylyshyn mere designation is not sufficient to define the
content of symbols, and therefore is not sufficient to support a classical or cognitive
theory. As discussed in detail in Chapter 8, Pylyshyn has developed a theory
of vision that requires indexing or designation as a primitive operation (Pylyshyn,
2003c, 2007). However, this theory recognizes that designation occurs without representing
the features of indexed entities, and therefore does not establish cognitive
content. As a result, indexing is a critical component of Pylyshyn’s theory—but
it is also a component that he explicitly labels as being non-representational and
non-cognitive.
Vera and Simon’s (1993) vagueness in defining the symbolic has been a central
concern in other critiques of their position. It has been claimed that Vera and Simon
omit one crucial characteristic in their definition of symbol system: the capability
of being a universal computing device (Wells, 1996). Wells (1996) noted in one
example that devices such as Brooks’ behaviour-based robots are not capable of
universal computation, one of the defining properties of a physical symbol system
(Newell & Simon, 1976). Wells argues that if a situated action model is not universal,
then it cannot be a physical symbol system, and therefore cannot be an instance of
the class of classical or symbolic theories.
The trajectory from Winograd’s (1972a) early classical research to his pioneering
articulation of the embodied approach (Winograd & Flores, 1987b) and the route
from Winograd and Flores’ book to Vera and Simon’s (1993) classical account of
situated action to the various responses that this account provoked raise a number
of issues.
Marks of the Classical? 323