Beginning in the 17th centure, scholars taken by the idea that language was the medium in which thought was conducted. First, they agreed that thought was exceptionally powerful, in the sense that there were no limits to the creation of ideas. In other words, man was in principle capable of an infinite variety of different thoughts. “reason is a universal instrument which can operate in all sorts of situations” (Descartes, 1637, p. 47). Second, language was a medium in which thought could be expressed, because it too was capable of infinite variety. Descartes expressed this as follows: “For it is a very remarkable fact that there are no men so dull-witted and stupid, not even madmen, that they are incapable of stringing together different words, and composing them into utterances, through which they let their thoughts be known” (p. 47). Modern linguists describe this as the creative aspect of language (Chomsky, 1965, 1966). “An essential property of language is that it provides the means for expressing indefinitely many thoughts and for reacting appropriately in an indefinite range of new situations” (Chomsky, 1965, p. 6).
The creativity of language is important to modern cognitive science, because it is assumed that this creativity is the product of a finite system. This idea was clearly expressed by Humboldt (1836/1999): “For language is quite peculiarly confronted by an unending and truly boundless domain, the essence of all that can be thought. It must therefore make infinite employment of finite means” (p. 91). While Humboldt’s theory of language has been argued to presage many of the key properties of modern generational grammars (Chomsky, 1966), it failed to detail a specific answer to the foundational question that it raised: how can a finite system produce the infinite? Modern generative grammars, in which a finite set of rules can produce infinite variety when they are applied recursively, can be seen as providing the answer that evaded Humboldt.