What Is the Language of Thought Hypothesis?

What is the Language of Thought Hypothesis?

LOTH is an empirical thesis about the nature of thought and thinking.

According to LOTH, thought and thinking are done in a mental language,

i.e. in a symbolic system physically realized in the brain of the relevant

organisms. In formulating LOTH, philosophers have in mind primarily the

variety of thoughts known as 'propositional attitudes'. Propositional

attitudes are the thoughts described by such sentence forms as 'S believes

that P', 'S hopes that P', 'S desires that P', etc., where 'S' refers to

the subject of the attitude, 'P' is any sentence, and 'that P' refers to

the proposition that is the object of the attitude. If we let 'A' stand

for such attitude verbs as 'believe', 'desire', 'hope', 'intend', 'think',

etc., then the propositional attitude statements all have the form: S As

that P.

LOTH can now be formulated more exactly as a hypothesis about the nature

of propositional attitudes. It can be characterized as the conjunction of

the following three theses (A), (B) and (C):

(A) Representational Theory of Mind (RTM): (cf. Field 1978: 37, Fodor

1987: 17)

(1) Representational Theory of Thought: For each propositional attitude A,

there is a unique and distinct (i.e. dedicated)[1] psychological relation

R, and for all propositions P and subjects S, S As that P if and only if

there is a mental representation #P# such that

(a) S bears R to #P#, and

(b) #P# means that P.

(2) Representational Theory of Thinking: Mental processes, thinking in

particular, consists of causal sequences of tokenings of mental

representations.

(B) Mental representations, which, as per (A1), constitute the direct

"objects" of propositional attitudes, belong to a representational or

symbolic system which is such that (cf. Fodor and Pylyshyn 1988:12-3)

(1) representations of the system have a combinatorial syntax and

semantics: structurally complex (molecular) representations are

systematically built up out of structurally simple (atomic) constituents,

and the semantic content of a molecular representation is a function of

the semantic content of its atomic constituents together with its

syntactic/formal structure, and

(2) the operations on representations (constituting, as per (A2), the

domain of mental processes, thinking) are causally sensitive to the

syntactic/formal structure of representations defined by this

combinatorial syntax.

(C) Functionalist Materialism. Mental representations so characterized

are, at some suitable level, functionally characterizable entities that

are realized by the physical properties of the subject having

propositional attitudes (if the subject is an organism, then the realizing

properties are presumably the neurophysiological properties in the brain

or the central nervous system of the organism).

The relation R in (A1), when RTM is combined with (B), is meant to be

understood as a computational/functional relation. The idea is that each

attitude is identified with a characteristic computational/functional role

played by the mental sentence that is the direct "object" of that kind of

attitude. (Scare quotes are necessary because it is more appropriate to

reserve 'object' for a proposition as we have done above, but as long as

we keep this in mind, it is harmless to use it in this way for LOT

sentences.) For instance, what makes a certain mental sentence an

(occurrent) belief might be that it is characteristically the output of

perceptual output systems and input to an inferential system that

interacts decision-theoretically with desires to produce further sentences

or actions. Or equivalently, we may think of belief sentences as those

that are accessible only to certain sorts of computational operations

appropriate for beliefs, but not to others. Similarly, desire-sentences

(and sentences for other attitudes) may be characterized by a different

set of operations that define a characteristic computational role for

them. In the literature it is customary to use the metaphor of a

"belief-box" (cf.