Focus and scope in child language

Languages vary in the ways in which words for conjunction and words for disjunctionare interpreted in sentences with negation. To explain the cross-linguistic differences,we propose that words for conjunction and disjunction are interpreted as positive polarity items (PPIs) in some languages (e.g., Mandarin) but not in other languages(e.g., English). If this is correct, then languages should converge on the sameintepretations when the polarity sensitivity of conjunction and disjunction is cancelled.One linguistic context that is known to cancel the polarity sensitivity of the English PPI some is in the predicate phrase of sentences with focus operators. We apply thisdiagnostic to the expressions for disjunction and conjunction in Mandarin and inEnglish. The expectation is that universal principles of semantic interpetation will become operative when conjunction and disjunction words appear in the predicate phrase of focus operators. Since conjunction words and disjunction words are notanalyzed as PPIs in this linguistic context, the meaning that is assigned to these wordsshould be the same in all human languages, including child language. By investigating both adult and child English and Mandarin, we show that focus operators do indeedcancel the polarity sensitivity of conjunction words and disjunction words intypologically different languages, and this permits us to witness the invariant logicalmeanings assigned to these locial connectives in human languages.