Abstract
The foregoing considerations support the conjecture that prototypes are semi-compositional in the sense that there exist unboundedly many combinations of nouns with non-exceptional adjectives, which satisfy the rule default-to-prototype and hence are compositional. Presumably there also exist unboundedly many combinations of nouns with exceptional adjectives, which violate DP and hence are non-compositional. An analysis of the connection between productivity and compositionality has been suggested by Robbins. He argues that, for the explanation of productivity, one need not assume that conceptual meanings always compose—it is enough that they compose in infinitely many cases. Since semi-compositionality entails the existence of unboundedly many non-compositional cases, non-compositionality cannot be dealt away with a finite list of idiomatic exceptions, but is a genuine feature of prototype semantics in natural language.