Islands, Learnability and the Lexicon

Island constraints on extraction are not universal. In Slavic languages they are stronger than in English, and in Scandinavian languages they are weaker. At least this is so for extraction from clausal complements to verbs, which I will focus on in this paper. As a first approximation (inaccurate but adequate for purposes of this section): all complement clauses are islands in Slavic, only WH-clauses are islands in English, and not even WH-clauses are islands in Scandinavian. We can conclude that island constraints are not fully innate; at least some children have to learn at least some facts about extractability. We can also establish, by reference to the Subset Principle, WHICH children have to do the learning.1 It must be the children learning a more generous language like Swedish, rather than those learning a more restricted language like Polish. To determine who learns we consider who has the necessary data to learn from. Given the assumption (standard though not undisputed) that learners have no access to systematic negative input,2 it follows that language-specific facts about islands must be learnable from positive data alone, i.e., by hearing sentences of the language. So it must be the Swedish learners and the English learners who discover from their input that it is possible to extract from complement clauses. The Polish learners (and hence ALL children) must believe innately that complement clauses are islands.3 In general: the strongest island constraints must be innate, and they must be progressively weakened by learners who encounter constructions that disobey them.