Question

Regarding Rabbi Shimon Shkop’s principle, which in your terminology is called consistency, and generally any legal effect such that if it takes effect it will not take effect, etc., a number of comments should be made, some of them well known. First, Rabbi Shimon Shkop did not gain very much with this; second, there is a difficulty against him from Tosafot and the medieval authorities (Rishonim).
1. The main gain of Rabbi Shimon Shkop is to explain all the unusual stipulations, such as “on condition that you have no claim against me for sustenance, clothing, and conjugal rights” — how can he uproot the obligation? And his answer is: if the obligation takes effect, the act is nullified. But there is not much gain in this, because it is explained in the Rashba’s responsa, part 2, siman 140, that in this case of “on condition that you have no claim against me for sustenance, clothing, and conjugal rights,” and similar cases, if the obligation regarding sustenance, clothing, and conjugal rights takes effect, the act is not nullified. Stipulations of this kind do not need to nullify the act at all, unlike other stipulations; rather, he simply says, “on condition that you have no claim against me for sustenance, clothing, and conjugal rights,” and lo and behold, it is nullified. It follows, then, that Rabbi Shimon Shkop’s answer did not help in the main issue.
And although in Tosafot and in the Rashba himself, and in all the medieval authorities in Ketubot, it is explained otherwise — for they asked that the act should be nullified — the answer to this is that it depends on Rabbi Meir and Rabbi Yehuda, whether from the negative you infer the positive, as Tosafot there preface. Since according to Rabbi Meir the case is where he says, “and if not, the act is nullified,” it is difficult why the act should not be nullified; see there. [And see the Hazon Ish, who wondered why they needed this, since even according to Rabbi Yehuda, from the positive you infer the negative.] And this is stated explicitly in Nachmanides on Bava Batra 126b. The reasoning is very difficult, because seemingly the dispute between Rabbi Meir and Rabbi Yehuda is only whether from the positive you infer the negative, but whether the act must be nullified in such a case — what does that have to do with this? This requires very careful study.

1. From the question of Tosafot and the medieval authorities — that the act should be nullified — it is clear against this principle that any legal effect such that if it takes effect, etc. And that is not what they answered there. This has already been asked. Rabbi Shimon Shkop is then left only with the proof from Tosafot in Gittin chapter 3, while Nachmanides disagrees with that.

At the time I heard an answer to this from Rabbi Chaim Yehuda Schreiber, may he live long, that this is not at all the issue in Tosafot and Nachmanides; they are occupied with defining whether she is called a married woman or not, but I do not remember it now.