The new version of the theory, called principles and parameters, replaced a single universal grammar for all the world’s languages with a set of “universal” principles governing the structure of language. These principles manifested themselves differently in each language. An analogy might be that we are all born with a basic set of tastes (sweet, sour, bitter, salty and umami) that interact with culture, history and geography to produce the present-day variations in world cuisine. The principles and parameters were a linguistic analogy to tastes. They interacted with culture (whether a child was learning Japanese or English) to produce today’s variation in languages as well as defined the set of human languages that were possible.

Languages such as Spanish form fully grammatical sentences without the need for separate subjects — for example, Tengo zapatos (“I have shoes”), in which the person who has the shoes, “I,” is indicated not by a separate word but by the “o” ending at the end of the verb. Chomsky contended that as soon as children encountered a few sentences of this type, their brains would set a switch to “on,” indicating that the sentence subject should be dropped. Then they would know that they could drop the subject in all their sentences.

The “subject-drop” parameter supposedly also determined other structural features of the language. This notion of universal principles fits many European languages reasonably well. But data from non-European languages turned out not to fit the revised version of Chomsky’s theory. Indeed, the research that had attempted to identify parameters, such as the subject-drop, ultimately led to the abandonment of the second incarnation of universal grammar because of its failure to stand up to scrutiny.