Acceptability judgments constitute the primary source of data on which such theories have been built, despite being susceptible to various extra-grammatical factors. Through a review of experimental and corpus-based research on avariety of syntactic phenomena and an in-depth examination of two case studies, Elaine J.

Francis argues for two main positions. The first is that converging evidence from online comprehension tasks, elicited production tasks, and corpora of naturally-occurring discourse can help to determine the sourcesof variation in acceptability judgments and to narrow down the range of plausible theoretical interpretations. The second is that the interpretation of judgment data depends crucially on the theoretical commitments and assumptions made, especially with respect to the nature of the syntax-semantics interface and the choice of either a categorical or a gradient notion of grammaticality.

The theoretical frameworks considered in this book include derivational theories (e.g. Minimalism, Principlesand Parameters), constraint-based theories (e.g. Sign-based Construction Grammar, Simpler Syntax), competition-based theories (e.g.

Stochastic Optimality Theory, Decathlon Model), and usage-based approaches. The volume shows that while acceptability judgment data are typically compatible with theassumptions of various theoretical frameworks, some gradient phenomena are best captured within frameworks that permit soft constraints-non-categorical grammatical constraints that encode the conventional preferences of language users.