[…] the identification of grammatical and semantic units has met with a number of objections [...]. The most important are these: (a) Some morphs are meaningless (“empty morphs”, e.g. 'to' with infinitives, the -'o'- of 'drunkometer'). [...] But none of these objections seems sufficient. (a) “Empty” morphs are an artifact of an Item-and-Arrangement grammar; in an IP grammar, they are not “empty”, but are the segmental markers of a transformation process.
- Weinreich (1963), Pag. 117