Ketubot

'Yes. [it is] from me.' R. Joseph said: Why should we be afraid? First,  he admits, and moreover, Rab Judah said [that] Samuel said: The halachah is according to Rabban Gamaliel.  Abaye said to him: And in this [case]. if he did not admit, would Rabban Gamaliel declare her as fit? Did not Samuel say to Rab Judah: 'Sharp-witted one! The halachah is according to Rabban Gamaliel, but you should not act upon it,  unless most men are fit for her,' whereas here most men are unfit for her!  — And according to your reasoning is not this [statement] in itself difficult? [First he says] 'The halachah [is. etc.'] [and then] 'do not act in practice [on it]'!  Hence you must say: The one ruling applies before  the other after it was done,  and in this case also it is like 'after it was done.' Abaye asked  Raba: Did R. Joshua Say: She is not believed? This would be in contradiction with the following: R. Joshua and R. Judah b. Bathyra testified concerning the widow  [of one who was] of a mixed family  that she is fit to marry a priest!  — He said to him: Now is this so?  There  the woman marries, and [in that case] she examines  and [then] marries; but here  the woman misconducts herself; does she first examine and then misconduct herself? Raba said: Is the contradiction [only] between [one statement of] R. Joshua and [the other Statement of] R. Joshua. [but] not  between [one Statement of] Rabban Gamaliel and [another Statement of] Rabban Gamaliel?  Surely the concluding clause  teaches: Rabban Gamaliel said to them: We accept your testimony,  but what can we do, since Rabban Johanan b. Zakkai decreed that no court be set up for this purpose.  because the priests will obey you to remove  but not to bring near?  — But, said Raba; there is no contradiction between [the statement of] Rabban Gamaliel and [the other statement of] Rabban Gamaliel, [because] there  it is sure'  [and] here  it is 'perhaps.'  Neither is there a contradiction between [the one statement of] R. Joshua and [the other statement of] R. Joshua, [because] there  there is one doubt  [and] here  there is a double doubt.  Therefore, according to Rabban Gamaliel the 'sure' is [so] strong  [a plea] that even where [there is only] one doubt  he declares [her] fit,  and the 'perhaps' is [so] weak [a plea]  that even where there is a double doubt  he declares [her] unfit.  [And] according to R. Joshua one doubt  is [so] strong that even in the case where [she pleads] 'sure' he declares [her] unfit,  and a double doubt  is [so] light  that even in the case where [she pleads] 'perhaps' he declares [her] fit. Our Rabbis taught: Which is the widow  [of one] of a mixed family? When there is with regard to it  [no doubt] on account of mamzeruth,  nathinuth  and on account of slaves of the kings.  R. Meir said: