Thus the ruling must be inseparable from the evidence: wherever the evidence is realised, the ruling is realised as well, so that the ruling is affirmed for every instance of the subject to which it applies.

Accordingly, one may sometimes reason from a particular to another particular that is co-extensive with it in both generality and specificity. A single star can be taken as proof of the star that invariably accompanies it, just as Capricorn (al-Jady) is inferred from Ursa Major (Banāt Naʿsh) and Ursa Major from Capricorn; or Capricorn from the northern direction and the north from Capricorn; or the sun from the east and the east from the sun. Of this kind, too, are the reports about our Prophet—may Allah bless him and grant him peace—found in the scriptures of the earlier prophets: they present descriptions that correspond to him exactly, being neither broader nor narrower than he is. The same holds for all things that are mutually concomitant: one of the pair is adduced as proof for the existence of the other, and its absence as proof for the latter’s absence. When what is indicated is particular, the sign is likewise particular.

At other times the sign necessitates the existence of the signified without the converse holding, as with the signs of the Creator, exalted is He: the existence of those signs entails His existence, whereas His existence does not entail theirs. All of them are signs pointing to His sanctified Essence, not to some universal abstraction whose very conception allows it to be shared between Him and others; such a universal is what syllogistic reasoning establishes.

The Qur’an therefore employs argument by means of signs, and it also employs—when establishing the reality of Divinity—an a fortiori analogy: whatever attribute of unblemished perfection is affirmed for a created being, the Lord is more entitled to it, and whatever imperfection a creature is declared free from, the Lord is even worthier of being declared free of it. The Almighty referred to this in His disputation with the polytheists who ascribed partners to Him, saying:

“He sets forth for you a parable drawn from your own selves: do you have, among those whom your right hands possess, any partners in the provision We have granted you, so that you become equal therein, fearing them as you fear one another?” (Qur’an 30:28)

And He, exalted be He, says:

“They ascribe daughters to Allah—glorified is He!—while for themselves they choose what they desire …” (Qur’an 16:57)