As the source explains it, qiyas is an argument formed from propositions such that accepting them commits one to a further proposition. The premises must be appropriately connected. A conclusion must follow from that connection, not from desire or a guess. A first test of formal validity is whether one could accept the premises while denying the conclusion consistently.
Opening interactive controls...
The basic definition of qiyas
Kinds of Argument: Syllogism, Premises, Conclusion and Three Terms
As the source explains it, qiyas is an argument formed from propositions such that accepting them commits one to a further proposition. The premises must be appropriately connected. A conclusion must follow from that connection, not from desire or a guess. A first test of formal validity is whether one could accept the premises while denying the conclusion consistently.