The Examination of the Four Sects

Kalam, Islamic speculative theology, aimed to defend the basic doctrines of Islam against philosophical attack. Al-Ghazali respected it as a defensive discipline but found it insufficient as a path to certainty: it presupposes the authority of Quran and hadith rather than establishing it, and its methods could not answer the philosopher who questioned those very foundations.

Philosophy offered the most systematic path to truth, and Al-Ghazali took it most seriously — he mastered Avicenna's system in three years of independent study before writing his refutation. But the philosophers' errors on eternity, divine knowledge, and resurrection showed that logic alone, however powerful, does not constrain conclusions to conform with revealed truth. The philosophical method is not self-correcting on the questions that matter most.

The Ismaili argument — that certain truth requires an infallible imam whose knowledge cannot be questioned — seemed to Al-Ghazali a clever exploitation of scepticism: if we cannot trust our own reason, we must defer to an authority. But he argued that this merely transfers the epistemological problem rather than solving it: how do we know the imam is infallible? The appeal to authority cannot bootstrap itself.

The examination of the four sects occupies the middle section of Deliverance from Error. Al-Ghazali's Incoherence of the Philosophers was a detailed follow-up to his treatment of the philosophers in this text.