In orthodox Islam there are now four schools of jurisprudence showing allowable differences in the treatment of the canon law. Most absurdly they are sometimes described as “sects”: this they are not as the differences of opinion are fully recognised as all equally orthodox. The followers of Abu Hanifa form the most numerous of these schools, the other three being all more or less reactionary as compared with it. The contemporary Malik b. Anas (d. 179) was openly actuated by dislike of the admission of _istihsan_ and the recognition thereby given to “opinion” for this he substituted what he called _istislah_ or “public expediency,” allowing analogy to be set aside only when its logical conclusion would be detrimental to the community. The difference seems to be more a verbal correction than a material change, but the underlying motive is clear and indicates an orthodox reaction. At the same time he attached much greater weight to the evidence of tradition, adding to it also the principle of _ijma_ or “consensus,” which in his system meant the common usage of Madina. Undoubtedly Ibn Malik’s position was theoretically sound: the Islamic state had taken form at Madina and nothing could give so clear light on the policy of the Prophet and his companions as the local customary law of the mother city. At the same time Ibn Malik took tradition quite seriously, indeed, the critical and scientific treatment of tradition begins with his manual known as the _Muwatta_. To-day Ibn Malik’s school prevails in Upper Egypt and North Africa west of Egypt. The third authority _ash-Shafi`i_ (d. 204) takes an intermediate position between Abu Hanifa and Ibn Malik, interpreting _ijma_ as the general usage of Islam, and not of the city of Madina alone. The fourth authority, _Ahmad b. Hanbal_ (d. 241), shows an entirely reactionary position which reverted to a close adherence to Qur´an and tradition; it carried great weight amongst the orthodox, especially in Baghdad, but now survives only in remote parts of Arabia.