or that a single cause should yield two different effects. And if what is predicated of it were not essential but merely incidental, then the very fact of its existence would stand in need of a cause; in that case necessary existence itself would become an effect—and that is impossible. All such discourse, and whatever resembles it, consists of terms shot through with ambiguity and vagueness. When the very words of a proof are obscure, and its structure is drawn out by countless divisions—disjunctive conditionals on the one hand and conjunctive entailments on the other, and so forth—the mind finds it hard to keep track of the points where error must be barred; it becomes a kind of ḥasabta li-ʿAmīdī (1). How like his procedure is theirs! Yet it is already plain that what he asserts is in fact false, for it entails combining contradictories and arguing from a single figure to every desired conclusion, whether affirmative or negative, or to every denial or every affirmation, or to a host of propositions embracing both truth and falsehood. For that reason they employ it only in the contentious realm of speculative disputes. Discerning scholars have recognized that his speech belongs to the class of riddles and puzzles devised to test—and ultimately to unpick—the intellect. These people, however, and those who follow their lead, imagine, and make others imagine, that what they advance are precious, conclusive demonstrations, while in truth they are sophistical arguments. By means of them they have corrupted minds and faiths to an extent known only to the Lord of creation.

Take, for instance, their use of the word “cause.” They apply it to four (2) well-known meanings in their terminology: the agent, the goal, the form, and the recipient. When they apply it to the end intended by the agent—that is, to what he has in view and desires to obtain by his act—such a cause is prior in intention and conception yet posterior in actual existence. A man buys food, for example, in order to eat it: his mental picture of eating and his resolve to do so come before the purchase of the food, whereas the act of eating itself occurs only after the purchase. Many other cases are analogous.