 al-Farabi |  Arabic and Islamic Philosophy, disciplines in: metaphysics |  Arabic and Islamic Philosophy, disciplines in: philosophy of language and logic |  Arabic and Islamic Philosophy, historical and methodological topics in: Greek sources |  Arabic and Islamic Philosophy, historical and methodological topics in: influence of Arabic and Islamic Philosophy on the Latin West |  Aristotle, General Topics: logic |  demonstration: medieval theories of |  Ibn Sina [Avicenna] |  logic, history of: modal logic |  logic: ancient |  logic: modal |  modality: medieval theories of |  syllogism: medieval theories of 