“Though this be madness, yet there is method in't”: The mamnū min al- arf (Diptotes) in Arabic Grammatical Tradition

This article discusses theories designed by medieval Arabic grammarians to explain one of the most puzzling topics in Arabic grammar, mamnū min al- arf (diptotes). The mainstream theory of mamnū min al- arf probably took on its definitive form in the early 4th/10th century; it differs from Sībawayhi's (d. ca 180/796) theory, yet consists of a generalisation of features found in the latter. A later modification, which retained its basic elements, was presented to the mainstream theory probably during the 7th/13th century. A radically different theory was presented by al-Suhaylī (d. 581/1185), who harshly criticised the mainstream theory as inadequate and arbitrary.