The “lost” Yaḥyā ibn ʿAdī treatises recently discovered in the Tehran codex Marwī 19 include a record of a philosophical debate instigated by the Ḥamdānid prince Sayf-al-Dawla. More precisely, Marwī 19 contains Yaḥyā’s adjudication of a dispute between an unnamed Opponent and Yaḥyā’s younger relative Ibrāhīm ibn ʿAdī (who also served as al-Fārābī’s assistant), along with Ibrāhīm's response to Yaḥyā’s adjudication, and Yaḥyā’s final word. At issue was a problem of Aristotelian exegesis: should “body” be understood as falling under the category of substance or under the category of quantity? The unnamed Opponent argues that body is a species of substance; Ibrāhīm argues that technically speaking, body is a species of quantity, and hence an accident; and Yaḥyā judges that body is a species of substance, though for very different reasons than the Opponent gives. For the first time, the Arabic text of this exchange is edited and translated into English. Also provided is an Introduction that sets the debate in historical context, and discusses in particular the possible influence of John Philoponus. The debate is interesting and important not only because of the philosophical ramifications of the issues under discussion, but because it constitutes evidence of dialectical practice among Arabic-speaking philosophers from the middle of the 10th century.

Most scholars of Islamic intellectual history now agree on the distortedness of the traditional Western portrayal of al-Ġazālī (d. 1111) as the defender of Muslim orthodoxy whose Incoherence of the Philosophers (Tahāfut al-falāsifa) was such a powerful critique that it caused the annihilation of philosophical activity in Islamic civilization. Some in fact are coming to the conclusion that al-Ġazālī's importance in the history of Islamic philosophy and theology derives as much from his assiduous incorporation of basic metaphysical ideas into central doctrines of Sunnī kalām, as from his far more celebrated bashing of the falāsifa. What is less well known is that al-Ġazālī's role in the ‘‘philosophizing” of Sunnī theology was not a lonely struggle by a single genius, but part of a broader trend that seems to have begun during Avicenna’s lifetime and that picked up speed in the first and second generations after Avicenna's death in 1037, with the work of al-Ġazālī's teacher, the Aš‘arite al-Gˇuwaynī (d. 1085), as well as of the Māturīdite al-Bazdawī (d. 1099), work that was carried forward by dozens of subsequent members of those two major Sunnī theological schools. It is clear, in fact, that the dividing line between the Sunnī theologians commonly referred to in the later Islamic tradition as mutaqaddimūn (‘‘early” or ‘‘ancient”), and those referred to as muta’aḫhḫirūn (‘‘late” or ‘‘modern”), lies not with al-Ġazālī but with Avicenna himself, and that the turn in Sunnī kalām was therefore Avicennian, not Ġazālian.

Did classical kalām debates about how thing (šay') and existent (maw[gcaron]ūd) relate to each other pave the way for Avicenna's distinction between essence (māhiyya) and existence (wu[gcaron]ūd)? There are some indications that the concept of thingness (šay'iyya) may have played a bridging role between the mutakallimūn's discussions and those of Avicenna. Nevertheless, Avicenna's appeals to thingness occur most densely in passages devoted to analyzing the relationship between efficient and final causes, an entirely Aristotelian topic. A philological question arises: should these passages be emended to read causality (sababiyya) in place of thingness (šay'iyya)? I argue that the balance of evidence compels us to retain thingness. For Avicenna, thingness is the respect in which the final cause is prior to the efficient cause (as well as to the formal and material causes); existence, by contrast, is the respect in which the efficient cause is prior to the final cause. In fact, over the course of Avicenna's career a progression from the kalām problematic of šay' v. maw[gcaron]ūd to his own problematic of māhiyya v. wu[gcaron]ūd can be detected in his discussions of efficient and final causation.