Pinker sees language as an ability unique to humans, produced by evolution to solve the specific problem of communication among social hunter-gatherers.

Deaf babies "babble" with their hands as others normally do with voice, and spontaneously invent sign languages with true grammar rather than a crude "me Tarzan, you Jane" pointing system.

Pinker also distinguishes language from humans' general reasoning ability, emphasizing that it is not simply a mark of advanced intelligence but rather a specialized "mental module".

He distinguishes the linguist's notion of grammar, such as the placement of adjectives, from formal rules such as those in the American English writing style guide.

Webster accepts Pinker's argument that, for ideological motives, twentieth-century social scientists have minimized the extent to which human nature is influenced by genetics.