The presence or absence of Principle A of the Binding Theory can be explained by a requirement at the syntax semantics interface. Principle A effects surface in the presence of unmodified self, where there is a requirement for the subject and object to be identical; this requirement triggers self-incorporation into the predicate. In contrast, modified self -incorporation is blocked in the syntax, giving rise to an asymmetric part-of relation. Given that self-incorporation is absent, we predict that Principle A effects do not surface, and this is exactly what we find.
