1,489. Conditions That Are Effective Retroactively

Hilchos Ishus 6:16

A conditional agreement takes effect when the condition is fulfilled so long as the person making it does not specify otherwise. However, if a man tells a woman, “You are consecrated to me as of this moment through this dinar if I give you 200 zuz…” and he later gives it to her, then marriage is effected retroactively, as of the time he gave her kiddushin, even though the condition was not fulfilled until much later. Therefore, if a second man were to consecrate her before the condition has been met, marriage is not effected with that person. The same is true in matters of divorce and financial transactions.

Hilchos Ishus 6:17

If a person makes a conditional agreement specifying that it is effective as of the time the condition is made (as opposed to when it is fulfilled), then it is not necessary for him to state the positive and negative ramifications of the condition, nor must the condition be stated before performing the related action. Even if he performs the action first, the condition is valid. It must, however, be a condition that is humanly possible to fulfill. If someone makes an impossible condition, he is assumed to be joking and there is no condition. If a person adds a condition to an agreement by saying “al m’nas” (“on the condition that…”), then the same rules apply as when one says “from this moment on,” i.e., it is not necessary to state the positive and negative ramifications of the condition, nor to state the condition before performing the related action.