Proponents of such views tend to subscribe, however, to defenses rooted in one or another feature of language. On syntactically-inspired views—the perspectives most indebted to the Vitruvian account—there is at least one architectural grammar or set of rules for guiding proper assemblage of parts and orientation, relation, and combination of whole architectural objects. Some late twentieth century architectural theory embraced a grammar framework (Alexander et al. 1977; Hillier and Hanson 1984); such a view also underwrites a formalist vision for CAAD (Mitchell 1990).  Adherents of the view (Summerson 1966) assign themselves the central task of identifying such rules. Even if this is achieved, though, a greater puzzle is whether there are identifiably preferable syntaxes—and what the criteria should look like. 