Yet the concept of ‘compositionality’ itself remains ill-defined, an issue this book addresses. Positioning compositionality as a cornerstone in linguistic theory, it argues that, contrary to widely held beliefs, there exist non-compositional languages, which shows that the concept of compositionality has empirical content. The author asserts that the existence of syntactic structure can flow from the fact that a compositional grammar cannot be delivered without prior agreement on the syntactic structure of the constituents.