You’re right and I’m wrong TB Kidushin 66

A classic Talmudic discussion is found on today’s daf TB Kiddushin 66. A kosher mikvah needs to contain a minimum of 40 se’a of water,  which is equal to 198 gallons of water. Let’s say that the mikvah originally had the minimum amount and let’s call this T1. Later on it was remeasured and found lacking the minimum requirement and let’s call this T2. Because there is a doubt exactly when the mikvah became unkosher, what is the halakhic status for everything that was immersed in the mikvah between T1 and T2? This is the discussion between Rabbi Tarfon and Rabbi Akiva.

“As we learned in a baraita: Rabbi Shimon said: An incident occurred with regard to a water reservoir of Diskim in Yavne, which had the presumptive status of being complete, i.e., they thought it contained forty se’a, the requisite amount for a ritual bath, and they measured it after a time and it was found to be deficient, as it contained less than that amount.

"With regard to all immersions of ritual purification performed in the reservoir before it was measured, Rabbi Tarfon would render them ritually pure, and Rabbi Akiva would render them ritually impure. The two Sages discussed the matter. Rabbi Tarfon said: This ritual bath retained the presumptive status of being whole throughout this period, and you are coming to declare it deficient in the past out of uncertainty. Do not deem it deficient out of uncertainty. Rabbi Akiva said in response: This person who immersed himself in that ritual bath retained the presumptive status of being ritually impure before he immersed. You are coming to purify him out of uncertainty. Do not deem him ritually pure out of uncertainty.

“Rabbi Tarfon said in response: There is a parable that illustrates this. A priest was standing and sacrificing offerings on the altar, and it became known that he is the son of a divorced woman or the son of a ḥalutza. The halakha is that his earlier service before this discovery remains valid. Rabbi Akiva said: A more accurate parable is that of a priest who was standing and sacrificing on the altar, and it became known that he is blemished. In this case, the halakha is that his earlier service is disqualified.

“Rabbi Tarfon said: You compared the case of a ritual bath found to be deficient to that of a blemished priest, whereas I compared it to the case of the son of a divorced woman or the son of a ḥalutza. Let us see to which case it is similar. If this case is similar to that of the son of a divorced woman or the son of a ḥalutza, let us treat it like the case of the son of a divorced woman or the son of a ḥalutza; if it is similar to the case of a blemished priest, let us treat it like that of a blemished priest.

“Rabbi Akiva began to analyze the matter: The disqualification of a ritual bath is by the testimony of an individual, as witnesses are not required to establish that a ritual bath is deficient, and likewise the disqualification of a blemished priest with regard to performing the Temple service is by the testimony of an individual. And do not let the halakha of the son of a divorced woman or the son of a ḥalutza prove otherwise, as his disqualification is by the testimony of two witnesses. Two witnesses are required to testify about one’s mother to disqualify him from performing the Temple service; one is insufficient.

“Alternatively, one can say: The disqualification of a ritual bath is due to the bath itself, and similarly, the disqualification of a blemished priest is due to the priest himself. And do not let the halakha of the son of a divorced woman or the son of a ḥalutza prove otherwise, as his disqualification is due to others, i.e., through his mother. Rabbi Tarfon said to him: Akiva, anyone who separates from you, it is as though he has separated from life itself. Rabbi Tarfon was impressed by Rabbi Akiva’s explanation and accepted it. This concludes the baraita.” (Sefaria.org translation)

The greatness of the tannaim is to admit they are wrong and except the other viewpoint. I only wish in politics and in other matters where people disagree, people would only admit they are wrong when presented with conclusive facts and logic. I’ll never understand how the Republicans can even consider people for the job of Speaker of the House who won’t admit or deny that Joe Biden won the 2020 election and is the legitimate president of the United States.

By the way, the halakha concerning those things immersed in the mikvah between T1 and T2 depends on the severity of the ritual unreadiness, tumah-טוּמְאָה. If the ritual unreadiness is severe, then everything that was immersed between T1 and T2 is retroactively ritually unready, tamai-טָמֵא. If the ritual unreadiness is rabbinic in origin, we can rule in a doubtful case that retroactively everything remains ritually ready, tahor-טָהוּר.