Editing Islamic philosophy (section)

== Logic ==
{{Main|Logic in Islamic philosophy}}

In early Islamic philosophy, [[logic]] played an important role. [[Sharia]] (Islamic law) placed importance on formulating standards of argument, which gave rise to a novel approach to logic in [[Kalam]], but this approach was later displaced by ideas from [[Greek philosophy]] and [[Hellenistic philosophy]] with the rise of the [[Mu'tazili]] philosophers, who highly valued [[Aristotle]]'s ''[[Organon]]''. The works of Hellenistic-influenced Islamic philosophers were crucial in the reception of Aristotelian logic in medieval Europe, along with the commentaries on the ''Organon'' by [[Averroes]]. The works of [[al-Farabi]], [[Avicenna]], [[al-Ghazali]] and other Muslim logicians who often criticized and corrected Aristotelian logic and introduced their own forms of logic, also played a central role in the subsequent development of European logic during the [[Renaissance]].

According to the ''[[Routledge Encyclopedia of Philosophy]]'':

{{Blockquote|For the Islamic philosophers, logic included not only the study of formal patterns of [[inference]] and their validity but also elements of the philosophy of language and even of [[epistemology]] and [[metaphysics]]. Because of territorial disputes with the Arabic grammarians, Islamic philosophers were very interested in working out the relationship between logic and language, and they devoted much discussion to the question of the subject matter and aims of logic in relation to reasoning and speech. In the area of formal logical analysis, they elaborated upon the theory of [[terminology|terms]], [[Proposition (philosophy)|proposition]]s and [[syllogism]]s as formulated in Aristotle's Categories, De interpretatione and Prior Analytics. In the spirit of Aristotle, they considered the syllogism to be the form to which all rational argumentation could be reduced, and they regarded syllogistic theory as the focal point of logic. Even poetics was considered as a syllogistic art in some fashion by most of the major Islamic Aristotelians.}}

Important developments made by Muslim logicians included the development of "Avicennian logic" as a replacement of Aristotelian logic. [[Avicenna]]'s [[system of logic]] was responsible for the introduction of [[hypothetical syllogism]], [[Temporal logic|temporal]] [[modal logic]] and [[Inductive reasoning|inductive logic]]. Other important developments in early Islamic philosophy include the development of a strict [[scientific citation|science of citation]], the [[isnad]] or "backing", and the development of a method to disprove claims, the [[ijtihad]], which was generally applied to many types of questions.

===Logic in Islamic law and theology===
Early forms of [[Analogy|analogical reasoning]], [[inductive reasoning]] and categorical [[syllogism]] were introduced in [[Fiqh]] (Islamic jurisprudence), [[Sharia]] and [[Kalam]] (Islamic theology) from the 7th century with the process of ''[[Qiyas]]'', before the Arabic translations of Aristotle's works. Later, during the [[Islamic Golden Age]], there was debate among Islamic philosophers, logicians and theologians over whether the term ''Qiyas'' refers to analogical reasoning, inductive reasoning or categorical syllogism. Some Islamic scholars argued that ''Qiyas'' refers to inductive reasoning. [[Ibn Hazm]] (994–1064) disagreed, arguing that ''Qiyas'' does not refer to inductive reasoning but to [[Syllogism|categorical syllogistic reasoning]] in a [[Reality|real]] sense and analogical reasoning in a [[metaphor]]ical sense. On the other hand, [[al-Ghazali]] (1058–1111; and, in modern times, [[Abu Muhammad Asem al-Maqdisi]]) argued that ''Qiyas'' refers to analogical reasoning in a real sense and categorical syllogism in a metaphorical sense. Other Islamic scholars at the time, however, argued that the term ''Qiyas'' refers to both analogical reasoning and categorical syllogism in a real sense.<ref>Wael B. Hallaq (1993), ''Ibn Taymiyya Against the Greek Logicians'', p. 48. Oxford University Press, {{ISBN|0-19-824043-0}}.</ref>

===Aristotelian logic===
The first original Arabic writings on logic were produced by [[al-Kindi]] (Alkindus) (805–873), who produced a summary on earlier logic up to his time. The first writings on logic with non-Aristotelian elements was produced by [[al-Farabi]] (Alfarabi) (873–950), who discussed the topics of future [[Contingency (philosophy)|contingent]]s, the [[number]] and relation of the [[Categories (Aristotle)|categories]], the relation between [[logic]] and [[grammar]], and non-Aristotelian forms of [[inference]].<ref name=Britannica>[https://www.britannica.com/ebc/article-65928 History of logic: Arabic logic], ''[[Encyclopædia Britannica]]''.</ref> He is also credited for categorizing logic into two separate groups, the first being "idea" and the second being "[[logical argument|proof]]".

[[Averroes]] (1126–1198), author of the most elaborate commentaries on Aristotelian logic, was the last major logician from [[al-Andalus]].

===Avicennian logic===
[[Avicenna]] (980–1037) developed his own system of logic known as "Avicennian logic" as an alternative to Aristotelian logic. By the 12th century, Avicennian logic had replaced Aristotelian logic as the dominant system of logic in the Islamic world.<ref>I. M. Bochenski (1961), "On the history of the history of logic", ''A history of formal logic'', pp. 4–10. Translated by I. Thomas, Notre Dame, [[Indiana University Press]]. ([[cf.]] [http://www.formalontology.it/islamic-philosophy.htm Ancient Islamic (Arabic and Persian) Logic and Ontology])</ref>

The first criticisms of Aristotelian logic were written by [[Avicenna]] (980–1037), who produced independent treatises on logic rather than commentaries. He criticized the logical school of Baghdad for their devotion to Aristotle at the time. He investigated the theory of [[definition]] and [[Classification theorems|classification]] and the [[Quantification (logic)|quantification]] of the [[Predicate (mathematical logic)|predicate]]s of categorical [[Proposition (philosophy)|proposition]]s, and developed an original theory on "[[Temporal logic|temporal]] [[Modal logic|modal]]" syllogism. Its premises included [[Grammatical modifier|modifier]]s such as "at all times", "at most times", and "at some time".

While [[Avicenna]] (980–1037) often relied on [[deductive reasoning]] in philosophy, he used a different approach in medicine. Ibn Sina contributed inventively to the development of [[inductive reasoning|inductive logic]], which he used to pioneer the idea of a [[syndrome]]. In his medical writings, Avicenna was the first to describe the [[Mill's Methods|methods of agreement, difference and concomitant variation]] which are critical to inductive logic and the [[scientific method]].<ref name=Goodman>Lenn Evan Goodman (2003), ''Islamic Humanism'', p. 155, Oxford University Press, {{ISBN|0-19-513580-6}}.</ref>

[[Ibn Hazm]] (994–1064) wrote the ''Scope of Logic'', in which he stressed on the importance of [[sense]] [[perception]] as a source of knowledge.<ref name=Herald>[http://www.islamherald.com/asp/explore/science/science_muslim_scientists.asp Science and Muslim Scientists] {{Webarchive|url=https://web.archive.org/web/20071020090525/http://www.islamherald.com/asp/explore/science/science_muslim_scientists.asp |date=2007-10-20 }}, Islam Herald.</ref> [[Al-Ghazali]] (Algazel) (1058–1111) had an important influence on the use of logic in theology, making use of Avicennian logic in [[Kalam]].<ref name=Britannica/>

[[Fakhr al-Din al-Razi]] (b. 1149) criticised Aristotle's "[[Syllogism|first figure]]" and developed a form of [[Inductive reasoning|inductive logic]], foreshadowing the system of inductive logic developed by [[John Stuart Mill]] (1806–1873). Systematic refutations of Greek logic were written by the [[Illuminationist philosophy|Illuminationist school]], founded by [[Shahab al-Din Suhrawardi]] (1155–1191), who developed the idea of "decisive necessity", an important innovation in the history of logical philosophical speculation,<ref>Another systematic refutation of Greek logic was written by [[Ibn Taymiyyah]] (1263–1328), the ''Ar-Radd 'ala al-Mantiqiyyin'' (''Refutation of Greek Logicians''), where he argued against the usefulness, though not the validity, of the [[syllogism]] See pp.&nbsp;253–54 of {{citation |publisher=Cambridge University Press |isbn=978-0-521-52069-0 |pages=247–65 |editor=Peter Adamson |editor2=Richard C. Taylor |last=Street |first=Tony |title=The Cambridge Companion to Arabic Philosophy |chapter=Logic |year=2005}}</ref> and in favour of [[inductive reasoning]].