The above classification of bid'a types is normal in classical Shari'a literature, being accepted by the four schools of orthodox fiqh. There have been only two significant exceptions to this understanding in the history of Islamic thought: the Zahiri school as articulated by Ibn Hazm, and one wing of the Hanbali madhhab, represented by Ibn Taymiya, who goes against the classical ijma' on this issue, and claims that all forms of innovation, good or bad, are un-Islamic.
Why is it, then, that so many Muslims now believe that innovation in any form is unacceptable in Islam? One factor has already been touched on: the mental complexes thrown up by insecurity, which incline people to find comfort in absolutist and literalist interpretations. Another lies in the influence of the well-financed neo-Hanbali madhhab called Wahhabism, whose leaders are famous for their rejection of all possibility of development.
In any case, armed with this more sophisticated and classical awareness of Islam's ability to acknowledge and assimilate novelty, we can understand how Muslim civilisation was able so quickly to produce novel academic disciplines to deal with new problems as these arose.
