It is well-known that disjunctive sentences “A or B” are ambiguous between an inclusive and exclusive disjunction. Recent work has discovered populations in which “A or B” is ambiguous between an inclusive disjunction and a conjunction. These populations include speakers of Warlpiri, American Sign Language (ASL), and English speaking children. So-called `free-choice’ inferences also show that the ambiguity is available in adult speakers of English as well. In all attested cases of this ambiguity, the conjunctive reading is overwhelmingly preferred over the disjunctive reading. This is not true with the more familiar inclusive/exclusive ambiguity.
This talk will review some of these findings, some of which come from our lab. We will argue that the conjunctive reading, when it’s available, is the result of a scalar implicature. However, this implicature differs from other implicatures in many ways: not only is the implicature strongly preferred, it is also acquired in the child earlier, it is faster to process, and it is easier to detect in embedded positions. We will discuss possible sources of this difference: one has to do with the alternatives used in the computation, and the other has to do with the pragmatics of questions and answers.