Sharh al-Isharat
Sharh al-Isharat (Explanation of the Signals) is Nasir al-Din al-Tusi’s philosophical commentary on Avicenna’s Al-Isharat wa al-Tanbihat (Remarks and Admonitions). It was written to defend Avicenna against the criticisms of Fakhr al-Din al-Razi.
Nasir al-Din al-Tusi (1201–1274) was a Persian polymath and vizier, often called the third teacher after Aristotle and Farabi. Avicenna’s Al-Isharat wa al-Tanbihat is his last and most influential work, dealing with logic, natural philosophy, theology, and metaphysics. It is mature and deliberately abstract, meant more as a guide for students to form correct premises and conclusions than as a fully worked-out argument.
Sharh al-Isharat is al-Tusi’s collection of writings detailing and defending Avicenna’s ideas against Razis. The debate over Avicenna’s philosophy continued into the 14th century with Qutb al-Din al-Razi’s al-Muhakamat. The work and its surrounding discussions became a central domain for Peripatetic philosophy, inspiring many later commentaries.
Al-Isharat was widely read in philosophical circles, with numerous commentaries, glosses, and summaries. While many early commentators wrote in Arabic, no Persian medieval translation of Al-Isharat is recorded. Al-Tusi’s own writings rebut Razis’ critiques and helped revive Avicenna’s philosophy in the East, making Sharh al-Isharat a landmark that influenced later thinkers, including Qutb al-Din al-Razi.
This page was last edited on 2 February 2026, at 20:28 (CET).