شروط صحة القياس خمسة
Five conditions govern the validity of qiyas.
ConditionRequired principle1Do not oppose an applicable text2Do not alter the textual ruling through extension3Extend only a ruling with an intelligible legal rationale4Base the effective cause on law, not language alone5Do not analogize a new case whose own ruling is already textual
The conditions do different work. The first two protect textual authority; the third and fourth test the legal cause; the fifth identifies where analogy has a legitimate place. Failure of one can invalidate the proposed analogy.