Nadeem F. Paracha in Dawn:
Though usually attributed to the beliefs of modern-day extremist movements in Islam, Islamic Fundamentalism (in the political context), is basically a firm belief in the theological musings of ancient Islamic jurists and scholars.
Islamic Fundamentalists all agree with Imam Ghazali’s dictum (in the twelfth century), that the ‘gates of ijtihad (rational debate) in Islam are now closed.’
After about three hundred years of open debate in the Islamic world between conservatives and the rationalists (Mu’tazilites), Ghazali insisted that a perfect synthesis (between the two) had been reached and that Islam’s social and spiritual philosophy had achieved completion.
The Mu’tazilites’ influence began declining during the rule of the ninth Abbasid caliph, Al-Muttawakkil, and the conservatives, who had ferociously debated with the rationalists, began their ascendance.
Modern-day Islamic Fundamentalism is rooted in this bygone intellectual triumph of the conservatives. Nevertheless, Islamic Fundamentalism never did attempt to form a so-called ‘Islamic state.’ Islamic Fundamentalists in the shape of scholars (ulema) and clergymen (maulvis and imams), mostly worked as advisers to caliphs and kings, or in the mosques. They were only interested in advocating Islamic laws, but never articulated a political plan that would carry these laws.
More here.