LANGUAGE OF THOUGHT

Language of thought theories fall primarily into two views. The first view sees the language of thought as an innate language known as mentalese, which is hypothesized to operate at a level below conscious awareness while at the same time operating at a higher level than the neural events in the brain. The second view supposes that the language of thought is not innate. Rather, the language of thought is natural language. So, if a person is an English speaker, the language of thought would be English.

The language of thought hypothesis claims that when a person has a thought such as the thought `grass is green', the content of that thought is represented in that person's mind by a sentence. However, according to Jerry Fodor, this sentence is not a natural language sentence like English or Japanese. It is a sentence of an entirely different language - the innate language of thought. The name often given to this language of thought is mentalese. An important feature of mentalese is that it is not a language that we have to learn through experience -- rather, we are born with it. Furthermore, even though we are not directly aware of the language, it underlies all of our thought processes and has a similar structure to that of any of the natural languages. This is to say that mentalese, like English or French, is structured according to certain rules of syntax, which determine how sentences are to be formed in order to give them a semantic (or meaningful) content.

The language of thought hypothesis draws an analogy between thought and computation. Mentalese is equivalent to the computational language of a digital computer, while higher level cognitive functions are achieved through the construction and manipulation of mentalese sentences. Within a digital computer, input received from the outside world (from a video camera say) is converted into strings of symbols, which represents the input data. These symbols constitute the computer's internal language and carry meaning when structured in certain ways.

According to Fodor's language of thought hypothesis, the same is true of the mind. Input from the environment is converted into strings of mentalese symbols, which can then be operated upon by processes in the brain. An innate set of rules determines how sentences are to be structured, and how they are to be manipulated. So, the content of my thought `grass is green' is written in my brain as a string of mentalese symbols -- or in other words, a mentalese sentence. Furthermore, the basic symbols that make up the mentalese sentence `grass is green’ are like the words of a natural language in that their meanings remain constant. The mentalese symbol that stands for `grass' will always stand for `grass', while the mentalese symbol that stands for `green' will always stand for `green'.