Q&A: Regarding Migo
Regarding Migo
Question
Are there rules for when we use a migo of argumentative strength and when a migo of credibility? I ask because I’ve seen many disputes among the medieval authorities (Rishonim) hinge on this—for example, in Tosafot’s question at the beginning of Bava Metzia, why don’t we say that a person is believed when he says “half of it is mine” by virtue of a migo that he could have claimed “all of it is mine”? And there are many answers among the medieval authorities. I saw people say that whoever answers that it is because of a migo of brazenness holds that migo is a matter of credibility, because from the standpoint of argumentative strength there is no problem of brazenness. On the other hand, those who answer that it is because one does not derive a migo from money to money only make sense if we say that the idea of migo is argumentative strength. If so, it is difficult that the Talmud in Rabbi Hiyya’s first case disqualifies migo because of brazenness, which proves that migo is a matter of credibility—unless the Rabbi will tell me that the question regarding migo, whether its nature is argumentative strength or brazenness, is a separate question in each case. And if so, then please, if possible, explain why each case would really be different.
Answer
That is a very difficult question. On the face of it, migo has both aspects, and in each case one must consider each of them separately. For example, a migo used to exempt someone from an oath must be only a “why would I lie?” argument, and argumentative strength does not help there, and so on. Therefore the proof from Rabbi Hiyya’s first case is not a proof, because there the issue is exempting him from an oath. Likewise, a migo from one who is not believed to one who is not believed (Rashba in Kiddushin 50) is also only a “why would I lie?” argument, and does not involve argumentative strength.