In the 1980s generative grammar recognized that functional material is able to project syntactic structure in conformity with the X-bar-format. This insight soon led to a considerable increase in the inventory of functional projections. The basic idea behind this line of theorizing, which goes by the name of cartography, is that sentence structure can be represented as a template of linearly ordered positions, each with their own syntactic and semantic import.

In recent years, however, a number of problems have been raised for this approach. For example, certain combinations of...