Logic in Islamic philosophy
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'''[[Logic]]''' played an important role '''in [[early Islamic philosophy]]'''. [[Islamic law]] placed importance on formulating standards of [[Logical argument|argument]], which gave rise to a novel approach to logic in [[Kalam]], as seen in the method of ''[[qiyas]]''. This approach, however, was later displaced to some extent by ideas from [[Greek philosophy]] and [[Hellenistic philosophy]] with the rise of the [[Mu'tazili]] school, who highly valued [[Aristotle]]'s ''[[Organon]]''. Aristotelian logic was itself later displaced by [[Avicennism#Avicennian logic|Avicennian logic]] in the [[Islamic Golden Age|medieval Islamic world]].
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 schools of logic, especially Avicennian logic, also played a central role in the subsequent development of European logic during the [[Renaissance]].
Important developments made by Muslim logicians included the first forms of non-Aristotelian logic, notably Avicennian logic, and the introduction of [[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 [[scientific method|scientific method of open inquiry]] to disprove claims, the [[ijtihad]], which could be generally applied to many types of questions.
==History==
According to the [[Routledge Encyclopedia of Philosophy]]:
{{quote|"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 [[terms]], [[proposition]]s and [[syllogism]]s as formulated in Aristotle's [[Categories (Aristotle)|Categories]], [[De Interpretatione|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."}}
{{quote|"Since logic was viewed as an organon or instrument by which to acquire knowledge, logic in the Islamic world also incorporated a general theory of argumentation focused upon epistemological aims. This element of Islamic logic centred upon the theory of demonstration found in Aristotle's Posterior Analytics, since demonstration was considered the ultimate goal sought by logic. Other elements of the theory of argumentation, such as [[dialectic]]s and [[rhetoric]], were viewed as secondary to demonstration, since it was held that these argument forms produced [[cognitive]] states inferior in certitude and stability to demonstration. The philosopher's aim was ultimately to demonstrate necessary and certain [[truth]]; the use of dialectical and rhetorical arguments was accounted for as preparatory to demonstration, as defensive of its conclusions, or as aimed at communicating its results to a broader audience."}}
===Logic in Islamic law and theology===
Early forms of [[Analogy|analogical reasoning]], [[inductive reasoning]] and categorical [[syllogism]] were introduced in [[Fiqh]] (Islamic jurisprudence), [[Sharia]] (Islamic law) 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 a logical [[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, which [[Ibn Hazm]] (994-1064) disagreed with, arguing that ''Qiyas'' does not refer to inductive reasoning, but refers to categorical syllogism 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 0198240430.</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=Iqbal>[[Muhammad Iqbal]], ''[[The Reconstruction of Religious Thought in Islam]]'', "The Spirit of Muslim Culture" ([[cf.]] [http://www.allamaiqbal.com/works/prose/english/reconstruction] and [http://www.witness-pioneer.org/vil/Books/MI_RRTI/chapter_05.htm])</ref> He wrote that the "first sources of all human knowledge are the soundly used senses and the intuitions of reason, combined with a correct understanding of a language." He also criticized some of the more traditionalist theologians who were opposed to the use of [[logic]] and argued that the first generations of [[Muslim]]s did not rely on logic. His response was that the early Muslims had witnessed the [[revelation]] directly, whereas the Muslims of his time have been exposed to contrasting beliefs, hence the use of logic is necessary in order to preserve the true teachings of [[Islam]].<ref>Seyyed [[Hossein Nasr]] and [[Oliver Leaman]] (1996), ''History of Islamic Philosophy'', pp. 107-109, [[Routledge]], ISBN 0415056675.</ref>
Ibn Hazm's ''Fisal'' (''Detailed Critical Examination'') also stressed the importance of sense perception as he realized that human [[reason]] can be flawed, and thus criticized some of the more rationalist theologians who placed too much emphasis on reason. While he recognized the importance of reason, since the [[Qur'an]] itself invites [[Introspection|reflection]], he argued that this reflection refers mainly to [[sense]] data, since the principles of reason are themselves derived entirely from sense [[experience]]. He concludes that reason is not a faculty for independent [[research]] or [[discovery]], but that that sense perception should be used in its place, an idea which forms the basis of [[empiricism]].<ref>[http://www.muslimphilosophy.com/hazm/ibnhazm.htm Ibn Hazm], ''Islamic Philosophy Online''.</ref>
[[Al-Ghazali]] (Algazel) (1058–1111) had an important influence on the use of logic in [[theology]], as he was the first to apply the [[Avicennism#Avicennian logic|Avicennian system]] of [[Temporal logic|temporal]] [[modal logic]] to Islamic theology.<ref name=Britannica/> Despite the logical sophistication of [[al-Ghazali]], the rise of the [[Ash'ari]] school from the 12th century slowly suffocated original work on logic in western Islamic regions such as the [[Maghreb]] and [[al-Andalus]], but logic continued to be studied in eastern Islamic regions such as the [[Levant]], [[Egypt]] and [[History of Iran|Persia]].
[[Ibn al-Nafis]] (1213-1288) wrote two major works dealing with logic in Islamic theology. ''Theologus Autodidactus'' was a fictional story dealing with many Islamic topics. Through its story, Ibn al-Nafis attempted to establish that the human [[mind]] is capable of [[Deductive reasoning|deducing]] the natural, philosophical and religious [[truth]]s of Islam through logical thinking.<ref name=Roubi/> In ''A Short Account of the Methodology of Hadith'', he demonstrated the use of logic in the classification of the [[hadith]]s into four categories: decidedly true (''maclūm al-sidq''), probably true (''yuz annu bihi'l-sidq''), probably false (''yuz annu bihi'l-kadhb'') and decidedly false (''maclūm al-kadhb'').<ref>Nahyan A. G. Fancy (2006), "Pulmonary Transit and Bodily Resurrection: The Interaction of Medicine, Philosophy and Religion in the Works of Ibn al-Nafīs (d. 1288)", p. 67-73, ''Electronic Theses and Dissertations'', [[University of Notre Dame]].[http://etd.nd.edu/ETD-db/theses/available/etd-11292006-152615]</ref>
===Aristotelian logic===
Most early Muslim logicians during the 8th and 9th centuries produced commentaries on [[Organon|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.<ref name=Britannica/>
[[Averroes|Ibn Rushd]] (Averroes) (1126–1198) was the last major logician from [[al-Andalus]], who wrote the most elaborate commentaries on Aristotelian logic. He was also the last major Aristotelian logician from the Islamic world.<ref name=Britannica/> Though his commentaries on Aristotelian logic had little influence in the Islamic world, his commentaries had a strong influence on [[Middle Ages|medieval Europe]] after the [[Latin translations of the 12th century]], and [[Averroism]] played an important role in establishing the Aristotelian tradition as the most popular form of logic in [[Europe]].
The last major logician to write a commentary on Aristotelian logic was [[Ibn al-Nafis]] (1213-1288), though he himself was not an Aristotelian logician. He wrote the ''Al-Wurayqat'' (''The Little Papers''), a commentary on [[Aristotle]]'s ''[[Organon]]'' and ''[[Rhetoric (Aristotle)|Rhetoric]]''.<ref name=Roubi>Dr. Abu Shadi Al-Roubi (1982), "Ibn Al-Nafis as a philosopher", ''Symposium on Ibn al-Nafis'', Second International Conference on Islamic Medicine: Islamic Medical Organization, Kuwait ([[cf.]] [http://www.islamset.com/isc/nafis/drroubi.html Ibn al-Nafis As a Philosopher], ''Encyclopedia of Islamic World'').</ref>
===Analogical inference, conditional syllogism, poetic syllogism===
Though [[al-Farabi]] (Alfarabi) (873–950) was mainly an Aristotelian logician, he introduced a number of non-Aristotelian elements of logic. He discussed the topics of future [[contingent]]s, the [[number]] and [[relation]] of the [[Category|categories]], the relation between [[logic]] and [[grammar]], and non-Aristotelian forms of [[inference]]. He is credited for categorizing logic into two separate groups, the first being "[[idea]]" and the second being "[[logical argument|proof]]".<ref name=Britannica/>
Al-Farabi also introduced the theories of [[conditional syllogism]] and [[Analogy|analogical inference]], which were not part of the Aristotelian tradition.<ref>Seymour Feldman (1964), "Rescher on Arabic Logic", ''The Journal of Philosophy'' '''61''' (22), p. 724-734 [726].</ref> Another addition al-Farabi made to the Aristotelian tradition was his introduction of the concept of [[Poetics|poetic]] [[syllogism]] in a commentary on Aristotle's ''[[Poetics (Aristotle)|Poetics]]''.<ref>{{citation|title=The Islamic roots of the poetic syllogism|journal=
College Literature|date=February 1996|last=Ludescher|first=Tanyss|url=http://findarticles.com/p/articles/mi_qa3709/is_199602/ai_n8749610 |accessdate=2008-02-29}}</ref>
===Avicennian logic===
{{main|Avicennism#Avicennian logic|l1=Avicennian logic}}
{{Avicenna}}
[[Avicenna|Ibn Sina]] (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'', p. 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> After the [[Latin translations of the 12th century]], Avicennian logic also influenced early [[Middle Ages|medieval European]] logicians such as [[Albertus Magnus]],<ref>Richard F. Washell (1973), "Logic, Language, and Albert the Great", ''Journal of the History of Ideas'' '''34''' (3), p. 445-450 [445].</ref> though Aristotelian logic later became more popular in Europe due to the strong influence of [[Averroism]].
Avicenna developed an early theory on [[hypothetical syllogism]], which formed the basis of his early [[risk factor]] analysis.<ref name=Goodman/> He also developed an early theory on [[propositional calculus]], which was an area of logic not covered in the Aristotelian tradition.<ref>Lenn Evan Goodman (1992), ''Avicenna'', p. 188, [[Routledge]], ISBN 041501929X.</ref> The first criticisms on Aristotelian logic were also written by Avicenna, who developed an original theory on [[Temporal logic|temporal]] [[Modal logic|modal]] [[syllogism]].<ref name=Britannica>[http://www.britannica.com/ebc/article-65928 History of logic: Arabic logic], ''[[Encyclopædia Britannica]]''.</ref> He also contributed inventively to the development of [[inductive reasoning|inductive logic]], being 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 0195135806.</ref>
[[Fakhr al-Din al-Razi]] (b. 1149) criticised Aristotle's "[[Syllogism|first figure]]" and formulated an early system of inductive logic, foreshadowing the system of inductive logic developed by [[John Stuart Mill]] (1806-1873).<ref name=Iqbal/> 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", which refers to the reduction of all modalities ([[necessity]], [[Logical possibility|possibility]], [[contingency]] and [[impossibility]]) to the single mode of necessity.<ref>Dr. Lotfollah Nabavi, [http://public.ut.ac.ir/html/fac/lit/articles.html Sohrevardi's Theory of Decisive Necessity and kripke's QSS System], ''Journal of Faculty of Literature and Human Sciences''.</ref> [[Ibn al-Nafis]] (1213-1288) wrote a book on Avicennian logic, which was a commentary of Avicenna's ''Al-Isharat'' (''The Signs'') and ''Al-Hidayah'' (''The Guidance'').<ref name=Roubi/> Another systematic refutation of Greek logic was written by [[Ibn Taymiyyah]] (1263-1328), who wrote the ''ar-Radd 'ala al-Mantiqiyyin'' (''Refutation of Greek Logicians''), in which he gave a [[Logical argument|proof]] for [[Inductive reasoning|induction]] being the only true form of [[argument]], which had an important influence on the development of the [[scientific method]] of [[observation]] and [[experiment]]ation.<ref name=Iqbal/> The ''Sharh al-takmil fi'l-mantiq'' written by Muhammad ibn Fayd Allah ibn Muhammad Amin al-Sharwani in the 15th century was the last major Arabic work on logic.<ref>[[Nicholas Rescher]] and Arnold vander Nat, "The Arabic Theory of Temporal Modal Syllogistic", in George Fadlo Hourani (1975), ''Essays on Islamic Philosophy and Science'', p. 189-221, [[State University of New York Press]], ISBN 0873952243.</ref>
===Fuzzy logic===
{{main|Fuzzy logic}}
In 1965, [[Lotfi Asker Zadeh]] founded [[fuzzy set]] theory as an extension of the classical notion of [[set]] and he founded the field of [[Fuzzy Mathematics]].
Later in 1973, Zadeh founded the field of [[Fuzzy logic]]. This was the first major contribution to logic from the Islamic world after more than five centuries.
==Major figures in Islamic logic==
*[[Al-Kindi]] (''Alkindus'') (805–873)
*[[Al-Farabi]] (''Alfarabi'') (873–950)
*[[Avicenna|Ibn Sina]] (''Avicenna'') (980–1037)
*[[Ibn Hazm]] (994-1064)
*[[Al-Ghazali]] (''Algazel'') (1058–1111)
*[[Averroes|Ibn Rushd]] (''Averroes'') (1126–1198)
*[[Fakhr al-Din al-Razi]] (1149-1210)
*[[Shahab al-Din Suhrawardi]] (''Sohrevardi'') (1155-1191)
*[[Ibn al-Nafis]] (1213-1288)
*[[Ibn Taymiyyah]] (1263-1328)
*Muhammad ibn Fayd Allah ibn Muhammad Amin al-Sharwani (15th century)
*[[Lotfi Asker Zadeh]] (b. 1921)
==See also==
*[[Early Islamic philosophy]]
*[[History of logic]]
*[[Logic]]
*[[Mill's Methods]]
==References==
{{reflist}}
==Resources==
*[http://www.rep.routledge.com/article/H017 Logic in Islamic philosophy], [[Routledge Encyclopedia of Philosophy]]. Routledge, 1998. (Alternatively, see [http://www.muslimphilosophy.com/ip/rep/H017 Logic in Islamic philosophy])
*[http://www.formalontology.it/islamic-philosophy.htm Ancient Islamic (Arabic and Persian) Logic and Ontology], at Raul Corazzon's ''Ontology. A resource guide for philosophers''.
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[[Category:History of logic]]