The Mishnayot in this perek work with the assumption that a woman who remarries with the permission of a Jewish court, only to discover that the witness was mistaken and her first husband is still alive, cannot return to her original husband, and must get a divorce from both husbands (see, for example, the first Mishna on daf 87b. In the Mishna on daf 94b, however, Rabbi Yose offers an alternative approach, saying “whoever disqualifies for others disqualifies for himself and whoever does not disqualify for others does not disqualify for himself.” This enigmatic statement is explained on our daf.
Rabbi Yose understood that according to the Tanna Kamma –
– if two unrelated men married sisters,
– and one man’s wife and brother-in-law (i.e. the other man) go traveling and are reported dead,
– if the man marries his sister-in-law under the assumption that his own wife is dead and that this woman is a widow,
– but then both his first wife and his brother-in-law return,
– then he will be allowed to return to his wife, but his sister-in-law will be forbidden to her husband (since she had willingly – albeit accidentally – lived with another man).
Rabbi Yose disagrees with this ruling, arguing that assuming that both couples were married and not merely betrothed to one-another, the same rule will apply to both. Either both couples can return to one-another, or neither one can.
The basic differences of opinion among the rishonim on these issues stem from different approaches to how to understand the rule that a woman who mistakenly married – based on testimony or on the ruling of a beit din – cannot return to her husband. According to some, it is a knas – a penalty – that is put in place in order to ensure that the woman will check very carefully before she accepts the testimony of witnesses who say that her husband died. Others suggest that the issue at hand is a concern lest people think that perhaps the man divorced his first wife and married the second woman, which would prohibit them from remarrying. Some apply both reasons to the conversation in the Gemara.