In analogy that proceeds by setting forth the cause, citing the original case is sometimes unnecessary, provided that the proof of the attribute’s causal efficacy does not depend upon it. If, however, establishing that efficacy does require the original, then the original must be mentioned, for it completes the evidence that the shared attribute is indeed causal; that shared attribute is the major term.

Those who draw a distinction between representative analogy (qiyās al-tamthīl) and the syllogism of inclusion (qiyās al-shumūl) attempt to show that one of the two yields only conjecture in certain instances. Yet the very cases that give nothing but probability in representative analogy likewise yield only probability in the inclusive syllogism. Conversely, whenever the latter is employed in matters that engender certainty, that same certainty is attained through representative analogy as well—and the certainty actually stands out more clearly there.

For example, in the syllogism of inclusion one might say: “Every human is an animal, and every animal is corporeal; therefore every human is corporeal.” Here “animal” is the middle term. The same middle term appears in representative analogy when one says, “The human being is corporeal by analogy with the horse and other animals,” for the fact that those creatures are animals entails that they are bodies, whether that entailment is the very cause or merely evidence of the cause. Since animality is present in the human being, he too is corporeal.

Should someone dispute the causal link in the original case and say, “We do not concede that animality entails corporeality,” the objection is really to the premise “Every animal is corporeal.” When the element common to the original and the branch is called a “cause,” what is meant is whatever entails the ruling, whether it is the productive cause that brings the ruling into actual existence or merely an indicator of it. The former is called causal analogy (qiyās ʿillah), the latter indicative analogy (qiyās dalālah).

Some scholars use the term “cause” for both, especially those who maintain that a cause is simply an identifier—a sign, mark, or proof—rather than a motivating factor. Those who hold that it can also denote the motive or stimulus—and this is the view of the leading jurists and the majority of Muslims—apply that usage with regard to the causes of actions. As for matters other than actions, “cause” may be explained as an attribute that entails the ruling, such as humanity’s entailment of animality, and animality—