Ijma
Ijmāʿ (إجماع) is an Arabic term referring ideally to the consensus of the ummah (the community of Muslims, or followers of Islam). In reality, ijma referred only to the consensus of traditional Islamic scholars (Arabic ulema) on particular points of Islamic law .
The hadith of Muhammad which states that "My community will never agree upon an error" is often cited as support for the validity of ijma. Sunni Muslims regard ijma as the third fundamental source of Sharia law, after the divine revelation of the Qur'an, the prophetic practice or Sunnah. The analogical reasoning or qiyas is described as fourth sourcein Sunni ISlam , whereas Shi'a Islam uses 'aql (intellect).Many conservative Muslim writers have claimed that the use of ijma' makes Islamic law compatible with democracy.
Various proponents of liberal movements within Islam criticize the traditional view that ijma' is only a consensus among traditional Islamic scholars (Arabic ulema). They claim that truly democratic consensus should involve the entire community rather than a small and conservative clerical class.