Najm al-Dīn 'Alī ibn 'Umar al-Qazwīnī al-Kātibī (died AH 675 / 1276 CE) was a

Persian Persian may refer to: * People and things from Iran, historically called ''Persia'' in the English language ** Persians, the majority ethnic group in Iran, not to be conflated with the Iranic peoples ** Persian language, an Iranian language of the ...

Islamic philosopher and

logician Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from premises ...

of the

Shafi`i The Shafii ( ar, شَافِعِي, translit=Shāfiʿī, also spelled Shafei) school, also known as Madhhab al-Shāfiʿī, is one of the four major traditional schools of religious law (madhhab) in the Sunnī branch of Islam. It was founded by ...

school. A student of

Athīr al-Dīn al-Abharī Athīr al‐Dīn al‐Mufaḍḍal ibn ʿUmar ibn al‐Mufaḍḍal al‐Samarqandī al‐Abharī, also known as Athīr al‐Dīn al‐Munajjim (d. in 1265 or 1262 Shabestar, Iran) was an Iranian muslim polymath, philosopher, astronomer, astrol ...

. His most important works are a treatise on logic, ''Al-Risala al-Shamsiyya'', and one on

metaphysics Metaphysics is the branch of philosophy that studies the fundamental nature of reality, the first principles of being, identity and change, space and time, causality, necessity, and possibility. It includes questions about the nature of conscio ...

and the natural sciences, ''Hikmat al-'Ain''. He helped establish the Maragha observatory along with Nasir al-Din al-Tusi and several other astronomers.

Logic

His work on logic, the ''al-Risāla al-Shamsiyya'' (''Logic for Shams al-Dīn''), was commonly used as the first major text on logic in madrasahs, right down until the twentieth century and is "perhaps the most studied logic textbook of all time". Al-Katibi's logic was largely inspired by the formal Avicennian system of temporal modal logic, but is more elaborate and departs from it in several ways. While Avicenna considered ten modalities and examined six of them, al-Katibi considers many more modalized propositions and examines thirteen which he considers 'customary to investigate'.

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* 1276 deaths 13th-century Iranian mathematicians Islamic philosophers Alchemists of the medieval Islamic world Year of birth unknown Iranian chemists 13th-century Iranian philosophers Iranian logicians 13th-century Iranian astronomers {{philosopher-stub

Logic

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