For the very fact that an agent is powerful in himself necessarily precedes his making another powerful; hence, one who lacks intrinsic power cannot possibly confer power upon anyone else. This impossibility is known, first, because of the invalidity of the prior circle, and second, because it is self-evident that one who is not powerful cannot empower another.

This is among the clearest proofs of tawḥīd, for it demonstrates that the Lord must possess power by His very Essence and cannot have acquired it from another. Accordingly, if two capable agents were hypothesised, their joining forces to produce one and the same effect would, by the plain dictate of reason and the unanimous verdict of thinking people, be intrinsically impossible. Once one of them performs the act independently, partnership is ruled out altogether, let alone the existence of another independent doer alongside him.

For this reason it is a rational axiom, acknowledged by all thinkers, that two complete efficient causes cannot converge upon a single effect; put differently, two sufficient causes cannot share one and the same caused entity.

Given this, if two deities were postulated, neither could independently bring about one and the same thing; rather, whenever one of them acted upon something, the other would necessarily be acting upon something else. This gives concrete meaning to the Almighty’s words:

“Had there been any gods besides God, each would surely have taken away what he had created.” (Qurʾān 23:91)

Moreover, if both are assumed to be capable, and if either can act without the other, then each could will the opposite of what the other wills, leading inevitably to mutual obstruction. Should both of their wills be fulfilled, two contradictory states would coexist; and if neither will were fulfilled, both would prove powerless and the object would be left devoid of one of the two contraries that every body must possess, such as one wishing