The validity of conjecture in topics is a significant and debated issue in the principles of jurisprudence. While the principle of "forbidden to rely purely on conjecture in religious rulings" is widely accepted among scholars, views differ regarding its validity in topics. Some, like Sheikh Anasari and his followers, consider it unreliable, whereas others, such as Abi-Salah al-Halabi, emphasize its validity. This paper aims to examine and prove the authority of conjecture in topics by analyzing the arguments and views of both supporters and opponents. The main evidence supporting its validity includes inductive reasoning (in principles, rules, and jurisprudential branches), custom (’ada), the principle of blockage (sadd al-dharai’), and the sharia’s ease. Conversely, consensus, texts prohibiting reliance on conjecture, and certain narrations are used to oppose its validity. Through critical analysis of these arguments, it is demonstrated that conjecture in topics—especially when attaining certainty is difficult—is indeed authoritative and compatible with rational and Shari’ah principles of ease. This issue gains increasing importance in the modern era, where facing complex and new issues makes achieving certainty challenging for both believers and jurists. This study seeks to support the acceptance of conjecture’s authority in deriving rulings, contributing to the adaptability of jurisprudence to contemporary needs and clarifying the relationship between religion and modern issues.