 One more clarification: ambiguity is a property of either sentences or perhaps the speech acts in which the sentences are used. But ambiguity of a sentence or sentences uttered does not necessarily result in any unclarity regarding what was expressed or meant by the speaker. There is no guarantee that unambiguous utterances will result in full univocal clear understanding either. In some syntactic contexts, the ambiguity won’t show up at all: ‘I want to see you duck’ is a case in which the NP interpretation of ‘duck’ is simply unavailable (especially with no comma after ‘you’). In many cases our best theory predicts an ambiguity in the sentence used, without predicting confusion over how the utterance ought to be interpreted. 