Islam is not a centralized religion, so there is not a single power uniformly defining shari’ah for all Muslims. Ijtihad makes shari’ah a truly living tradition; while some aspects are fixed because of clarity in the sources of revelation or consensus amongst scholars, many other aspects depend on context. Thus fiqh may differ across times and cultures. Because realizing shari’ah is a ground-up process dependent upon thousands of scholars spread across the world, historically scholars have disagreed. In Sunni Islam, this resulted in four surviving different schools of fiqh, called madhhab (pl., madhahib), offering different approaches to determining fiqh. At one point in history there were more than seventy different schools in Sunni Islam! In Shia Islam there is one major and two minor schools of fiqh. On an issue that is not fixed, a scholar of one madhhab may have a different approach to understanding the application of shari’ah than a scholar of another madhhab, but both are generally considered correct because accepting multiple schools of fiqh means you must also accept a plurality of opinions. Thus on many issues, there is no one Islamic opinion according.