They claim that observing its rules protects the mind from slipping into error, but the matter is not so. For if a scale itself required another scale, that would lead to an infinite regress. Besides, when a person’s innate disposition (fiṭrah) is sound, it already weighs things with the rational balance; if that disposition is sluggish or corrupt, the study of logic—were it flawless—would only increase its sluggishness and corruption. Hence most of those who rely on this tool in their studies inevitably flounder, failing to produce sound rational proofs; and whenever they do succeed in presenting a proper proof, they abandon logical formalism because of its impotence, prolixity, circuitousness, its tendency to obscure what is self-evident, and its profusion of mistakes that mislead others.

Every syllogism in existence can be reduced to the categorical syllogism.

If it is objected, “What you said—that the universal (shumūl) syllogism goes back to analogical reasoning—applies to the categorical syllogism but not to the conditional (istithnāʾī) syllogism. In the conditional, the conclusion or its negation is actually stated, whereas in the categorical it is only implicit. The conditional is composed of connected hypotheticals (entailment) and disjunctives (division). Undoubtedly the middle term in the categorical syllogism can serve as the common factor in analogical reasoning, unlike the conditional.”

The answer has several aspects:

First, entailment and division—in the form “This entails that; wherever the antecedent is found, the consequent is found”—constitute a universal proposition. It may therefore be used both analogically and universally: one compares some of its particulars with others and makes the shared element the basis of the ruling. Likewise, when we say, “This is either such-and-such or such-and-such,” the statement is also universal and can be clarified either by analogy or by universality. Hence rulings established in a general formulation can be applied by analogy, comparing certain instances with others and making the common meaning the operative cause of the judgment.

Second, every syllogism in the world can be reduced to the categorical form. Thus, if one states conditionally, “If the prayer is valid, then the person praying is in a state of purification,” one can equally say, “Every person who prays is purified,” or “Prayer entails purification,” and similar categorical formulations. In this context the middle term is the rule that affirming the antecedent affirms the consequent, and denying the consequent denies the antecedent.