Every version of every language, therefore, provides its own distinctive window on human language capability in general. Whether spoken by hundreds of millions, like Chinese, or by a mere handful, like Arapaho, every human tongue offers an equally valuable glimpse of the Universal Grammar that is the common heritage of our entire species. Languages have many different systems of rules governing such matters as plurals, verb tenses, conditional and subjunctive statements, the significance of word order in sentences, and the uses of pitch and tone.
Some languages allow double negatives.
A newborn infant has no predisposition to choose any of these options, but possesses a natural ability to master any of them. In order to understand this universal language facility, Roeper has made a specialty of studying young children in the process of learning their native languages. Seymour has also made children's language the focus of his professional life, but he looks at the subject from another perspective. He does not entirely share the linguist's laissez faire attitude that there is no incorrect grammar, only deficits in language ability. As speech-language pathologists, we're forced to make certain decisions that something is sufficiently deviant from 'normal' that there is a need for some clinical intervention.