Ever wonder why we say that a baseball player "flied out to center" instead of "flew out to center"? Pinker explained that the meaning of the word 'fly' has changed as the word changed from a verb to the noun 'fly ball' and then back to a verb. Over that transformation, the suffix for the past tense has also changed.
Using the complexity of the German language to prove his assertions, Pinker argued that both the rules of grammar and the rote memorization of words play essential roles in the development of language.
While children use the rules of conjugation to create the correct forms of all regular verbs, he argued, they must memorize the forms of all irregular verbs. The most common irregular verbs, such as "be," "go" and "have," are never regularized because they are so common.
Pinker conceded that although change in the English language and the function of words is inevitable, he said that some degenerative transformations "ought to be resisted on aesthetic grounds."