Text 15. It has been the custom of our predecessors to place a chapter on dialectics (jadal) in their logical works. But since the science of juristic dialectic (khilâf) of our times does not need it, I have brought in its stead a canon for the art of disputation and its order, the proper formulation of speech [in disputation] and its rectification. This [art] is, with respect to establishing a thesis and explaining it, just like logic with respect to deliberation and thought; for, through it we are kept on the desired path and are saved from the recalcitrance of speech. I have set it out in two sections, the first, on the ordering and etiquette of debate, the second, on error and its  causes.[28]