When Rav would happen to come to Darshish he would declare: Who will be married to me for the day? Similarly, when Rav Naḥman would come to Shekhantziv he would declare: Who will be married to me for the day?
PROBLEM 1: Mamzerim (bastards)
But wasn’t it taught in a baraita that Rabbi Eliezer ben Ya’akov says: A man should not marry a woman in one state and go and marry another woman in a different state, lest a match be arranged between the child of this wife with the child of that wife who are unaware of their relationship. This would lead to a brother marrying his sister or a father marrying his daughter, filling the whole world in its entirety with mamzerim. And concerning this it is stated: “And the land became filled with lewdness” (Leviticus 19:29).
SOLUTION 1: (Parentage is actually known)
The Sages say in response: The Sages generate publicity. Since they were well-known, the identity of their children was also undoubtedly known. Therefore, there was no concern that errors of this kind would befall their children.
Calderon: Why did the rabbis prefer to get entangled in a complicated procedure like a one-day marriage instead of simply sleeping with an anonymous woman under the cover of night? There is precedent for this sort of deviance - we read several times in the Talmud about one who is seized by his evil impulse: "He should dress in black and wrap himself in black and go to an unknown city." Was turning to a prostitute beneath the dignity of the rabbis, whereas they would not hesitate to co-opt the sacred institution of marriage for the sake of preserving their own reputations?
PROBLEM 2: (Menstrual blood)
The Gemara raises a different problem with the practice of Rav and Rav Naḥman. But didn’t Rava say: With regard to one who proposed marriage to a woman and she agreed, she is required to sit seven clean days, as perhaps due to the anticipatory desire she might not notice that she experienced menstrual bleeding and she is therefore impure. How, then, could these amora’im marry a woman on the day that they proposed?
SOLUTION 2: (advanced notice)
The Gemara answers: The Sages would inform them by sending messengers before their arrival. The messenger would announce that the amora sought to marry a local woman. The woman who agreed would in fact wait seven clean days before marrying him.
ALTERNATE SOLUTION 2: (Available woman keeps sexual urges at bay - No sex)
And if you wish, say instead that these Sages were not actually proposing marriage; rather, they proposed so that they could be in seclusion with the women, without consummating the relationship. Since the women knew that the marriage would not be consummated, they did not experience anticipatory desire. There is no similarity between one who has bread in his basket and one who does not have bread in his basket. One who does not have access to bread experiences hunger more acutely than one for whom bread is available and can eat whenever he chooses. Similarly, an unmarried man experiences a more acute desire. In order to mitigate that desire, these Sages made certain that women would be designated for them.
Calderon: Why does the notion of multiple wives seem like a realistic solution to the Tosafot who, like Rashi, were students of Rabbuinu Gershom of Mainz, who explicitly outlawed marriage to more than one woman at a time?
Was it just that the Tosafot did not dare to admit that the Talmud is giving voice to a dream that lies buried in every man's heart? Was the one-night stand too disturbing to them, such that they had to assume that a shared future was in the cards?
There is no doubt that all of the exegetical effort to explain this passage attests to the difficulty it posed to generations of scholars. Clearly, the practice of "Who will be mine for a day" does not accord with Jewish law or with our moral institutions.
[The same conversation, with nearly verbatim problems and solutions posed as written above from Yoma 18b, also occurs in Yevamot 37b, but there it ends with this one additional statement:]
COMMENT/ SOLUTION 3: (Just say no)
The Gemara cites an additional statement: It is taught in a baraita that Rabbi Eliezer ben Ya’akov says: A man should not marry his wife when at the same time his intention is to divorce her, because it is stated: “Do not devise evil against your neighbor, as he dwells securely with you” (Proverbs 3:29). It is wrong for one to intend to undermine the feelings of security that another has with him.
The sanctity of Christian matrimony has influenced Western culture, and we are accustomed to viewing the romance of love "'til death do us part" as the final stage of cultural evolution. By the same token we are accustomed to viewing the culture of the rabbis - whose primary expectation of marriage was the fulfillment of the commandment to procreate- as a betrayal of love.
The concept of "marriage for a day" allows us to test how we would behave if we were freed of the accepted and enshrined conventions that govern our lives -the material, the social, the psychological. Perhaps in reality things could be otherwise. If we consider Rav and Rav Nachman as alternatives to the love as we know it, we may find ourselves -Western liberals confronting Eastern rabbis- not unlike the members of a stuffy bourgeoisie confronting our more liberated anarchist counterparts.
All Calderon quotes from "A Bride for One Night," Jewish Publication Society (2001, 2014 English translation).