Yevamot

Now, if it be agreed that the required information was supplied  one well understands why they  did not abstain.  If, however, it be assumed that no such information was supplied, one can still understand why Beth Shammai did not abstain from using the utensils of Beth Hillel, since that which was regarded by Beth Hillel as ritually unclean was deemed by Beth Shammai to be ritually clean; but why did not Beth Hillel abstain from using the utensils of Beth Shammai when that which was deemed clean by Beth Shammai was regarded as unclean by Beth Hillel? Must it not, then, be concluded that they supplied them with the required information! Our point is thus proved. In what respect is the one  more conclusive proof  than the other?  — It might have been thought that the case of a rival  receives due publicity,  hence it was necessary [for the inference from the final clause] to be cited. [Reverting to] the previous text, 'R. Eleazar said: Although Beth Shammai and Beth Hillel are in disagreement on the question of rivals they concede that a bastard is only he who is descended from a marriage forbidden as incest and punishable by kareth'. Who concedes? If it be said, Beth Shammai to Beth Hillel;  this, surely, is obvious, since the children of those who are guilty of the infringement of a negative precept  are deemed legitimate.  Must it not consequently be the case that Beth Hillel conceded to Beth Shammai;  but this very case is subject to the penalty of kareth! — The fact is that Beth Shammai conceded to Beth Hillel; and the purpose was to exclude the opinion of R. Akiba, who maintains that a descendant from persons guilty of the infringement of a negative precept is deemed a bastard.  Hence it was taught  that a descendant from persons guilty of the infringement of a negative precept is not deemed a bastard. Come and hear: Although Beth Shammai and Beth Hillel are in disagreement on the questions of rivals, sisters,  an old bill of divorce,  a doubtfully married woman,  a woman whom her husband had divorced  and who stayed with him over the night in an inn,  money, valuables, a perutah and the value of a perutah,  Beth Shammai did not, nevertheless, abstain from marrying women of the families of Beth Hillel, nor did Beth Hillel refrain from marrying those of Beth Shammai. This is to teach you that they shewed love and friendship towards one another, thus putting into practice the Scriptural text, Love ye truth and peace.  R. Simeon said: They abstained [from marrying] in cases of certainty but did not abstain in doubtful cases.  Now, if you agree that they  acted [in accordance with their own views] one can well understand why they abstained. If, however, you assume that they did not so act, why did they abstain? — And how do you understand this? Even if it be granted that they did act (in accordance with their own views], one can only understand why Beth Hillel abstained from intermarrying with Beth Shammai, because the latter, in the opinion of Beth Hillel, were guilty of offences involving kareth and their descendants were consequently bastards; as to Beth Shammai, however, why did they abstain from intermarrying with Beth Hillel, when they were [even in the opinion of Beth Shammai] only guilty of the infringement of a negative precept and [their descendants] were consequently legitimate? — As R. Nahman said elsewhere that the statement was required only for the case of the rival herself, so here also the Statement is required for the case of the rival herself. Why is a doubtful case different from a case of a certainty? Obviously because it is forbidden. Is not a doubtful case also forbidden? — Do not read, 'from a doubtful case', but 'from a case unknown', since when they received the information they kept away.  And what does he teach us thereby? That they shewed love and friendship to one another? But this is exactly the same as the first clause!  — He teaches us this: That the entire Mishnah represents the views of R. Simeon. Come and hear: R. Johanan b. Nuri said: 'How is this law  to be promulgated in Israel? Were we to act in accordance with the ruling of Beth Shammai,  the child would, in accordance with the ruling of Beth Hillel, be a bastard.  And were we to act in accordance with the ruling of Beth Hillel,  the child, according to the ruling of Beth Shammai, would be tainted;  come, then, and let us issue an ordinance that the rivals