When categories go back to parts of speech

Faced with the complexity of natural languages, contemporary categorial grammars have significantly increased the number of their basic categories. With such a theoretical choice, the notion of category becomes a black box which no longer clarifies the dependent relationships linking the different sorts of expres­sions. Furthermore, no new definition of basic category is provided, nor any expli­cit introduction criteria. Focusing on Lambek’s pregroup grammar, this paper points out the consequences of the proliferation of basic categories. The accounts of infinitives and relative clauses will show the ad hoc use of new basic categories and the need for ad hoc grammatical rules. Paradoxically, we obtain an anachro­nistic model which uses a very up-to-date algebraic method with categories work­ing as the traditional parts of speech.