[A common claim we hear in beit din is that the obligation written in a document signed by the defendant is not binding because he did not understand it. While we have often mentioned that this claim is generally not accepted, we will now take a closer look at the rule’s source and parameters.]
The Shulchan Aruch (Choshen Mishpat 61:13; ibid. 68:2; ibid. 45:3) and the Rama (Even Haezer 66:13) say that one is obligated by all that is written in a document signed by witnesses because witnesses would not sign if they did not see that the parties were aware of what was written in the document. The Rashba is cited as the source of this ruling, which is not a simple claim, as we will see by surveying some of his responsa, starting with the major one cited:
1) An ignorant husband said he did not understand one of the conditions in his wife’s ketuba. The Rashba quotes Rabbi Meir as saying we accept the husband’s claim. The Rashba did not like that position, as we can assume that the witnesses knew that he agreed and because according to Rabbi Meir, any agreement is vulnerable to being deemed worthless if it involves a party who can claim he is too ignorant to understand. The Rashba concludes the responsum by saying: "What can I do, for the elder (Rabbi Meir) has already ruled." The Beit Yosef (EH 66) objects to the Rashba’s humility and accepts his stated position.
2) Regarding a ketuba that limited the boundaries of a field set aside for a wife, the Rashba says that it is clear that a bride does not pay attention to the provisions of a ketuba but relies on others.
3) Repeats his thesis in opposition to Rabbi Meir’s ruling.
4) Certainly in a case where one relies on others and signs himself on a document he did not read, we say that he accepted upon himself everything that was written there.
#4 adds something new, almost opposite from the other responsa. The possibility that a party did not understand does not exempt him, as signing without knowledge is itself an acceptance of whatever might happen to be written.
There are different conjectures among the Acharonim as to whether the Rashba changed his mind and which of his positions is the final one. The Knesset Hagedola, though, suggests distinctions to reconcile the various responsa: 1. One cannot deny the validity of a major provision of a document but can do so regarding a relative detail. 2. Only in the case of a bride, where the circumstances lead to the assumption that she was unaware, would we believe that the document does not obligate.
In our case, neither of the limiting factors applies, as we are discussing a significant matter under normal circumstances. Furthermore, in a case where a person signs himself (as opposed to witnesses), the matter is even more binding (Shut Rav B. Ashkenazi 24).
There are rulings of dayanim and logic to confirm the approach that written obligations are binding as is, except in extreme cases, i.e., a case where the person who signed clearly did not know all the details included and it is illogical that he would agree to its conditions.