Kuntres HaSefekos (5:3): It seems to be me that Tosfos and the Nemukei Yosef are talking about a dispute between Tannaim and Amoraim as can be seen from their language. In such a case the judge does not need to struggle and find proofs to the validity of the different opinions. That is because it is impossible for us to refute the view of a particular Tanna or Amora with decisive proofs – because ruach hakodesh is manifest in them. Our Sages have already said about Talmudic sages, “These and those are the words of the living Gd. Therefore the judge must decide based on what makes sense to him – but he can’t prove or disprove whether a particular view is correct. In contrast the Rosh was describing the postTalmudic situation and wrote that when two gedolim are in disagreement about a matter then the judge needs to look for proper proofs to decide between them. That is because from the day that the Talmud was closed – the fountains of wisdom have been sealed and therefore each person has the right to disagree with his predecessors with what he considers proof. Thus in the post-Talmudic world it is within the realm of the possible to decide between views by bringing proofs to the reasoning of one side over the other. We see this in the books of the Achronim where they refute the words of their predecessors with clear proofs.