Just so I understand — any reasoning you have, you’ll issue a halakhic ruling based on it against all the medieval authorities (Rishonim)?

First, it depends how strong the reasoning is. The medieval authorities do not have absolute authority, so this is a question of degree: how explicit the medieval authorities are, and how broad the consensus there is, as against how clear my own reasoning is to me. Usually, when the reasoning is completely clear to me, it is unlikely that there would be a broad, explicit, unanimous consensus among the medieval authorities against it. Second, a ruling like Meiri’s is not against all the medieval authorities. He argues that in his own time the earlier approaches were no longer correct, and therefore he is not arguing against the holders of those views. On the contrary, his claim is that in his own day everyone would agree that the Jewish law should be changed.

Obviously they don’t have absolute authority, and Meiri’s words (according to your understanding) are clear. The question is whether, let’s say, we accept that the explanation of Meiri is not as you say, which would mean that your reasoning goes against all the medieval authorities, who stated their words without qualification, that a non-Jew is a non-Jew simply by virtue of being a non-Jew and not because of his behavior — would you still go with your reasoning against all the medieval authorities? From your words I understand that the answer is yes.

Indeed. And again I repeat: the fact that they spoke without qualification does not prove that this was their view. Those were the non-Jews around them.