Pragmatic tolerance: implications for the acquisition of informativeness and implicature.

Recent investigations of the acquisition of scalar implicature report that young children do not reliably reject a sentence with a weak scalar term, e.g. 'some of the books are red', when it is used as a description of a situation where a stronger statement is true, e.g. where all the books are red. This is taken as evidence that children do not interpret the sentence with the implicature that the stronger statement does not hold. We propose that (a) these tasks cannot differentiate between actual implicature derivation and mere sensitivity to violations of informativeness; and that (b) children's apparent failure is not due to lack of competence (whether with informativeness or implicature) but due to their tolerance of pragmatic violations. We report three studies with 5-to-6-year-old English-speaking children and adults employing utterances involving scalar and non-scalar expressions. These show that both age-groups are competent with informativeness, but also tolerant of pragmatic infelicity. These findings have implications for the well-established literature on whether children are aware of ambiguity in referential communication tasks.