It is theoretically possible that structural ambiguity could be filtered out of natural languages. In (3)-(8) unambiguous paraphrases in English were given; perhaps structurally unambiguous paraphrases in English are always available. But it is unclear whether precise rules could be given which would effect this filtering. One can see why logicians might prefer artificial languages: they are constructed from the ground up in such a way that structural ambiguity is impossible.