Ibn Sīnā stated that the method he followed to establish the Necessary Existent and its necessary implications differs from that of his philosophical predecessors; rather, it is a newly devised method.

This helps show that he constructed it by combining what he took from the Muʿtazilites and similar Muslim theologians with the principles of his philosophical predecessors. What he took from the Muslim theologians in this regard is closer to the truth than what he took from his predecessors. For he adopted their principle that singling out one of two similar, originated things rather than the other requires something to determine that distinction. This is true.

From this he concluded that singling out a contingent being for existence requires a necessitating cause. This too is true.

They may, however, dispute with him whether a contingent being can be eternal. For they—and rational people generally—say that a contingent being can only be originated. He—and his predecessors—concede this to them.

Moreover, Abū al-Husayn and others like him say:

“Without an agent, a contingently existing being would have no greater claim to existence than to nonexistence.”

They also say:

“It is impossible for an eternal being’s existence to be necessitated by an agent, because an agent is understood to be that which brings something into being from nonexistence, whereas an eternal being has no state of nonexistence.”

For this reason, they say:

“The existence of an eternal being is necessary, and there is no reason for its existence to be necessary in one state rather than another.”

Thus, it is established that its existence is necessary in every state, making its nonexistence impossible.