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

We have seen that the structures a physical symbol system manipulates have
two different lives, syntactic and semantic. Because of this, there is a corollary to
the formalist’s motto, which might be called the semanticist’s motto: “If you understand
the semantics, then you can take the syntax for granted.” That is, if you have
a semantic interpretation of a physical symbol system’s symbolic expressions, then
you can use this semantic interpretation to predict the future behaviour of the
system—the future meanings that it will generate—without having to say anything
about the underlying physical mechanisms that work to preserve the semantics.
We have seen that one of the fundamental properties of a physical symbol system
is designation, which is a relation between the system and the world that provides
interpretations to its symbolic expressions (Newell, 1980; Newell & Simon, 1976).
More generally, it could be said that symbolic expressions are intentional—they are
about some state of affairs in the world. This notion of intentionality is rooted in
the philosophy of Franz Brentano (Brentano, 1995). Brentano used intentionality to
distinguish the mental from the physical: “We found that the intentional in-existence,
the reference to something as an object, is a distinguishing characteristic of
all mental phenomena. No physical phenomenon exhibits anything similar” (p. 97).
To assume that human cognition is the product of a physical symbol system is
to also assume that mental states are intentional in Brentano’s sense. In accord with
the semanticist’s motto, the intentionality of mental states can be used to generate a
theory of other people, a theory that can be used to predict the behaviour of another
person. This is accomplished by adopting what is known as the intentional stance
(Dennett, 1987).
The intentional stance uses the presumed contents of someone’s mental states
to predict their behaviour. It begins by assuming that another person possesses
intentional mental states such as beliefs, desires, or goals. As a result, the intentional
stance involves describing other people with propositional attitudes.
A propositional attitude is a statement that relates a person to a proposition
or statement of fact. For example, if I said to someone “Charles Ives’ music anticipated
minimalism,” they could describe me with the propositional attitude “Dawson
believes that Charles Ives’ music anticipated minimalism.” Propositional attitudes
are of interest to philosophy because they raise a number of interesting logical problems.
For example, the propositional attitude describing me could be true, but at the
same time its propositional component could be false (for instance, if Ives’ music
bore no relationship to minimalism at all!). Propositional attitudes are found everywhere
in our language, suggesting that a key element of our understanding of others
is the use of the intentional stance.
In addition to describing other people with propositional attitudes, the intentional
stance requires that other people are assumed to be rational. To assume that a
person is rational is to assume that there are meaningful relationships between the
Elements of Classical Cognitive Science 83