Nanzan Linguistics: Special Issue 5, 95-107 ©2008 Vincenzo Moscati WHEN CHILDREN ARE STRONGER THAN ADULTS Vincenzo Moscati University of Siena 1. Introduction Ambiguity is a pervasive feature of human languages revealed in a variety of different domains and logic composition is arguably one of them. The problem is evident if we take into consideration sentences containing more than one logic operator. One example is given by sentences containing a negative operator and a quantificational element in subject position, as in sentence (1) below: (1) Every horse didn’t jump over the fence. a. Every horse is such as it did not jump over the fence. b. Not every horse jumped over the fence. This sentence can be used to describe two different states of the world, illustrated in the paraphrases in (1a-b). According to the first interpretation (1a), it describes a situation in which none of the horses of a given set was able to cross an obstacle. The alternative meaning (1b), instead, refers to a different situation in which only some of the horses jumped over the fence. Whatever theoretical solution we adopt for deriving both (1a) and (1b), what is important here is the fact that the hearer of (1) must be able to map this sequence of words onto two distinct logic representations. Given that multiple logic representations are possible for a single sentence, one question to answer for development theories is whether children grasp all the meanings of logical ambiguous sentences. However, not all sentences with two operators are ambiguous. In fact language might adopt special strategies to avoid ambiguity by means of specific constraints in force on scope assignment. Another issue for developmental theories is to determine whether children are sensitive to language specific rules able to restrict the set of possible interpretations. This point can be illustrated considering the case of polarity items. For example, English existential quantifiers split into two set of items: negative polarity items as any (Ladusaw 1979) and the complementary set constituted by positive polarity items as some. Contrary to (1), sentence (2) is unambiguous in English and the standard explanation for the impossibility of (2a) relies on the polarity of some (Szabolcsi 2004):