The measurement is limited to this scope and does not exceed it because "all information is of two types: negation and affirmation. Negation is nothing because it is an expression of the non-existent, and therefore analogy is not permissible in it. Affirmation is the existent." The existent is of two types: identical and multiple. The multiple is of two types: similar and dissimilar. Analogy is permissible between the similar, and if we find a commonality between the dissimilar, we unite them, otherwise we leave them.

Defining the scope of correct analogy defines its conditions, and Al-Mahdi made them five conditions: multiplicity, specificity, commonality, correspondence, and equality. Multiplicity means the availability of two parties, one of which is the subject of analogy and the other is the analog. Multiplicity is a condition for the impossibility of measuring a thing against itself.

Specificity means that each of the two parties is distinguished by an inherent characteristic. The commentator of "A'azz ma yutlab" explained it by saying, "The characteristic, according to Al-Ma'sum, may God be pleased with him, is the inherent quality by which the essence of a thing is constituted and distinguished from its opposites."

From this, it appears that specificity achieves multiplicity, so they are two close conditions.

The commonality is what is shared between the two parties, and mere sharing of the word is not enough for correct analogy. Rather, a conceptual commonality must be available, which is of two types: the first is an intellectual meaning represented by similarity and genus. Similarity is like comparing jewels to each other in what is permissible, required, and impossible. Genus is like comparing all accidents to motion in the impossibility of their existence in a subject, and they are of the same genus. The second is a customary meaning, such as comparing animal genera to each other in what is permissible for them and the rulings that apply to them.

As for correspondence, Al-Mahdi did not clarify its meaning, and perhaps he means the certainty of the existence of the commonality in the same source and page.

Source: Ibn Tumart (37) Source: Unknown, Commentary on "A'azz ma yutlab" (38) Source: Ibn Tumart, Treatise on the fact that Sharia is not established by reason (39) The commonality in jurisprudential analogy corresponds to the effective cause.