Such methods were used by the early Muslim generations and the leading scholars in addressing questions of this kind, as Imam Ahmad and the leading scholars of Islam before and after him employed similar methods. The Quran likewise uses such reasoning to establish the “fundamentals of religion,” including questions of Allah’s oneness, His attributes, the resurrection, and related matters.

An example is that when He, glorified is He, announced the resurrection—knowledge of which depends on knowing that it is possible, since what is impossible cannot occur—He demonstrated its possibility with the utmost clarity. He did not follow the approach of “groups of speculative theologians,” who establish possibility in reality merely on the basis of possibility in thought. They say: “This is possible because, if its existence were assumed, that assumption would entail nothing impossible.” Yet this very premise is at issue: how is it known that assuming its existence would entail nothing impossible? What is impossible here includes both what is impossible in itself and what is impossible owing to something else.

Possibility in thought is, in fact, the absence of knowledge that something is impossible. Not knowing that something is impossible does not entail knowing that it is possible in reality. Rather, it remains in the mind as something neither known to be impossible nor known to be possible in reality. This is possibility in thought.

Allah, glorified and exalted is He, did not content Himself with this when demonstrating the possibility of resurrection. Something may be impossible—even if owing to something else—although the mind does not know it to be impossible. Possibility in reality is different: once it is known, the thing cannot be impossible.

A person knows that something is possible in reality sometimes by knowing that it exists, sometimes by knowing that something comparable to it exists, and sometimes by knowing that something greater than it exists. For the existence of something is evidence that what is less than it is all the more possible.