And minds that differ cannot agree upon a certainty without collusion or mutual awareness unless there are grounds that compel certainty. Otherwise, if there were nothing to warrant certainty—or even a probable judgment—these numerous groups, despite their differing aims and intellectual abilities and their lack of collusion, would not reach certainty where none was warranted.

It is therefore clear that they possessed conclusive evidence establishing consensus as a binding authority that must be followed and must not be opposed.

Moreover, Sunnis and Shī‘a agree that when ‘Alī is among them, their consensus is authoritative. This cannot be on account of ‘Alī’s infallibility, since his infallibility has only been established through consensus. Their principal basis for this is the consensus that others lack infallibility, for neither textual evidence nor reason rules out infallibility in anyone else (1).

This is one indication of the Rāfidah’s inconsistency: they built the foundation of their religion upon consensus, then challenged it. Challenging it, however, challenges ‘Alī’s infallibility, leaving them with nothing to rely upon. This is how they proceed in most of the positions peculiar to them.

For this reason, al-Sha‘bī said of them:

“They cling to endings that have no beginnings”—that is, branches that have no roots.

If consensus is not their proof (2), his infallibility is not established; and if it is authoritative, there is no need for his infallibility. Thus, on either assumption, it is established that their judgment cannot be