Pinker criticizes a number of common ideas about language, for example that children must be taught to use it, that most people's
grammar is poor, that the quality of language is steadily declining, that the kind of linguistic facilities that a language provides (for example, some languages have words to describe light and dark, but no words for colors) has a heavy influence on a person's possible range of thoughts (the
Sapir–Whorf hypothesis), and that nonhuman animals have been taught language (see
Great ape language). Pinker sees language as an ability unique to humans, produced by
evolution to solve the specific problem of communication among social hunter-gatherers. He compares language to other species' specialized adaptations such as
spiders' web-weaving or
beavers' dam-building behavior, calling all three "
instincts". By calling language an instinct, Pinker means that it is not a human invention in the sense that
metalworking and even
writing are. While only some human cultures possess these
technologies, all cultures possess language. As further evidence for the universality of language, Pinker—mainly relying on the work of
Derek Bickerton—notes that children spontaneously invent a consistent grammatical speech (a
creole) even if they grow up among a mixed-culture population speaking an informal trade
pidgin with no consistent rules. 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. Language (speech) also develops in the absence of formal instruction or active attempts by parents to correct children's grammar. These signs suggest that rather than being a human invention, language is an innate human ability. 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. He argues that because rules like "
a preposition is not a proper word to end a sentence with" must be explicitly taught, they are irrelevant to actual communication and should be ignored. Pinker attempts to trace the outlines of the language instinct by citing his own studies of language acquisition in children, and the works of many other linguists and psychologists in multiple fields, as well as numerous examples from popular culture. He notes, for instance, that specific types of brain damage cause specific impairments of language such as
Broca's aphasia or
Wernicke's aphasia, that specific types of grammatical construction are especially hard to understand, and that there seems to be a
critical period in childhood for language development just as there is a critical period for vision development in cats. Much of the book refers to Chomsky's concept of a
universal grammar, a meta-grammar into which all human languages fit. Pinker explains that a universal grammar represents specific structures in the human brain that recognize the general rules of other humans' speech, such as whether the local language places adjectives before or after nouns, and begin a specialized and very rapid learning process not explainable as reasoning from
first principles or pure logic. This learning machinery exists only during a specific critical period of childhood and is then disassembled for thrift, freeing resources in an energy-hungry brain. ==Reception==