If we already know safek dioraisa l'chumrah, why do we need safek d'rabanan l'kulah?
closed as unclear what you're asking by Ypnypn, Shmuel Brin, Gershon Gold, DanF, Isaac Moses♦ Jan 17 '16 at 2:55
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The reason we need to have both rules is because one does not follow logically from the other. Given just safeik deoraita l'chumra we could potentially also say safeik derabanan l'chumra. Likewise vice-versa.