Our Gemara discusses cases in which a person is sent to deliver money to another person, but he cannot locate the intended recipient. In such a case, should the messenger return it to the sender, or does the money already belong to the missing person and thus should be given to his inheritors? Aside from the obvious possibilities – that it should go back to the original sender (or to his children if he has died) or that it should go to the children of the person it was meant for – the Gemara also raises the possibility of dividing the money between them or the possibility of shuda.
The suggestion that the money should be divided is based on traditional approaches to safek – situations of halakhic doubt. If we do not know what to do, splitting it between the possible recipients seems logical and fair. With regard to the ruling of shuda we find a disagreement between Rashi and Tosafot. Rashi understands that the obligation of the members of the court – or, in our case, the messenger – is to establish to the best of their ability what the intention of the original sender was. Based on that evaluation of the situation, the messenger is obligated to do what he thinks is most appropriate. Rabbeinu Tam is quoted in Tosafot as disagreeing and ruling that shuda allows the court (or the messenger) to choose either party without concern for the desire of the original sender. Even though the decision appears to be arbitrary, Rabbeinu Tam prefers it over a decision to divide the money; were we to give both sides equal shares, clearly one party would be cheated out of half of what they deserve. If it is given to one person, it is at least possible that the true recipient will be getting what was meant for him.