If Hadith are unreliable, much of Islamic law and practice lacks a solid foundation. If they’re reliable, persistent disagreement among scholars and contradictions with the quran undermines their authority.
P1. The Qur’an does not provide enough detail to derive full Islamic law and practice (e.g., exact method of salah, zakat rates, most hudud, many marriage/divorce rules), so Sharia depends heavily on Hadith.
P2. If Hadith are unreliable (fabrications, unknown chains, bias, contradictions), then the bulk of Islamic law and ritual has no solid, certain foundation, and Islam is left without a clear, complete, divinely preserved way of life.
P3. If Hadith are reliable, then:
C. Therefore, whether Hadith are treated as unreliable or reliable, Islam loses a coherent, trustworthy foundation for its law and practice.
Admit the isnad system and classification (sahih/hasan/da’if) cannot guarantee truth.
Then:
Islam’s claim to provide a complete, preserved guidance and detailed way of life collapses.
The authority and coherence of the Sunnah—and thus of Islamic law—are undermined.
So either Hadith are too weak to support Islam’s system, or strong enough to expose its contradictions. In both cases, the foundation of Islamic law and practice is fatally compromised.