The distinction between decisive (qaṭʿī) and probabilistic (ẓannī) evidence is essential in theological reasoning. Decisive evidence can establish certainty within its proper scope. Probabilistic evidence may support a strong conclusion without necessarily providing the same degree of certainty.
Not every theological question occupies the same rank. Certain fundamentals of faith require certainty, while more detailed or subsidiary disputes may admit probabilistic arguments and scholarly variation. Ignoring that distinction can turn a limited disagreement into an exaggerated claim about foundational belief.
Example: The fundamental affirmation of God's oneness and the preferred interpretation of a particular disputed report do not necessarily have equal evidentiary status. Theologians must first ask what sort of claim is under discussion before determining the standard and strength of proof needed.