Is logic innate?

Arguments are presented supporting logical nativism: the conjecture that humans have an innate logic faculty. In making a case for logical nativism, this article concentrates on children's acquisition of the logical concept of disjunction. Despite the widespread belief to the contrary, the interpretation of disjunction in human languages is arguably the same as it is in classical logic, namely inclusive–or. The argument proceeds with empirical support for the view that the inclusive–or is the meaning of disjunction in human languages, from studies of child language development and from cross-linguistic research. Evidence is presented showing that young children adhere to universal semantic principles that characterize adult linguistic competence across languages. Several a priori arguments are also offered in favour of logical nativism. These arguments show that logic, like Socratic virtue and like certain aspects of language, is not learned and cannot be taught — thus supporting a strong form of innateness.