Third Factors and the Performance Interface in Language Design

This paper shows that systematic properties of performance systems can play an important role within the biolinguistic perspective on language by providing third-factor explanations for crucial design features of human language. In particular, it is demonstrated that the performance interface in language design contributes to the biolinguistic research program in three ways: (i) it can provide additional support for current views on UG, as shown in the context of complex center-embedding; (ii) it can revise current conceptions of UG by relegating widely assumed grammatical constraints to properties of the performance systems, as pointed out in the context of lin-ear ordering; (iii) it can contribute to explaining heretofore unexplained data that are disallowed by the grammar, but can be explained by systematic properties of the performance systems.