Of course, the brain is a biological organ, and above we have noted another
aspect of the biological foundations of language: the claim that the language
faculty is a product of humangenetic endowment. Species-specificity is consistent
with such a claim, but we might ask how we could obtain additional empirical
evidence for it. One source of such evidence may be provided by the study of
genetically caused disorders of language. If the availability of the language faculty
(and the consequent ability to acquire a grammar) is indeed genetically controlled,
then we would expect failures of this genetic control to result in language
disorders. It is, therefore, of considerable interest that there is a group of
language-impaired people who suffer from Specific Language Impairment
(SLI), a language disorder which must be clearly distinguished from the disorders
introduced above, which are acquired as the result of damage to the brain. This