Sībawayhi’s Kitāb devotes a large section to the analysis of different typologies of verbal valency in Arabic. This analysis is unprecedented in other linguistic traditions in both extent and depth, and largely outperforms later Arab grammarians’ treatment in its peculiar concern for what would be called thematic roles or actants in contemporary linguistics, which has shown a growing interest in this matter for the last decades.
Valency in the Kitāb is analyzed from a prevalent logic-semantic perspective which strikingly differs from the sharper distinction of the level of lafẓ and maʿnā, which became normative for later grammarians. In particular, Sībawayhi accurately distinguishes verbs that ‘pass over’ (taʿaddā) one or more objects (mafʿūl) and/or subjects/agents (fāʿil), which refers to the semantic-thematic role of the arguments rather than to their ‘surface’ realization as fāʿil or mafʿūl. This analysis is an interesting earliest example of the type of classification of verb classes, which has become a central issue in some contemporary lexicalist approaches to grammar. The paper presents a taxonomy of verb classes detected by Sībawayhi and a discussion of implications of such an early treatment of verbal valency for both the history of linguistics and current linguistic analyses of Arabic.