The Arabic term ijtihad means “the utmost effort an individual can put forth in an activity.” In a legal sense, it refers to independent reasoning, a scholar's careful and complete use of mental abilities to find a solution to a legal problem.
During the early years of Islamic society, when religious law was being formulated, qualified jurists practiced a type of ijtihad, known as ra'y. In cases where the Qur'an and sunnah did not provide clear guidelines for a decision, jurists used ra'y to render legal decisions that were intended to serve the interests of the Muslim community.
As religious law developed, ra'y came to be considered insufficiently rigorous to ensure that legal judgments were in keeping with the Qur'an and sunnah. At the same time, the meaning and scope of ijtihad became more clearly defined. Ijtihad was limited to a systematic method of interpreting the law on the basis of authoritative texts (the Qur'an and sunnah). According to this method, the ruling of the Qur'an and sunnah may be extended to a new problem as long as the precedent and the new situation share the same cause.
The practice of ijtihad became a religious duty and a mujtahid (one qualified to practice ijtihad) who failed to use it was thought to have sinned. According to Islamic legal theory and practice, a jurist must meet certain requirements to become a mujtahid. The individual must have a thorough knowledge of Arabic, the Qur'an, and the sunnah, as well as of legal theory and precedent.
By the beginning of the 900s, the Sunni jurists believed that all major matters of religious law had been addressed. Following established legal precedents and traditions, or taqlid, became more important than ijtihad. Unlike the Sunnis, however, Shi'i Muslims continued to emphasize the importance of ijtihad. Although both branches of Islam accept the Qur'an as the primary source of law, they rely on different sets of prophetic traditions. While the Sunnis believe in consensus as the source of truth after the time of the Prophet, Twelver Shi'is consider the sayings and writings of the twelve imams to be infallible. Accordingly, Twelvers acknowledge human reasoning and intellect as a legal source that supplements the Qur'an and other revealed texts.
During the 1600s, Sunni reformers began to criticize taqlid and called for greater practice of ijtihad in legal matters. They argued that jurists should not rely on the practices developed by generations of religious scholars. Instead, they should establish doctrine and rules of behavior by interpreting the original and sacred sources of Islam—the Qur'an and the sunnah.
In recent years, Muslim reformers have advocated the replacement of taqlid with ijtihad as a way to confront legal issues raised by contact with modern Western society. In practice, Islamic jurists have typically revised the law in response to specific issues, making virtually no attempt to build a new legal philosophy on which to base necessary changes to existing Islamic law. As a result, some scholars question whether their efforts can even be considered ijtihad. See also Law; Shafi'i .