I recently found money in a shul. Does the money belong to the shul or to me, or does it still belong to the one who lost it and I have to return it?
You are posing two questions. One is the status of the money vis-à-vis the one who lost it. The second is that if it no longer belongs to the loser, may you take it or was it already acquired by the shul before you picked it up?
Let us begin by addressing the first question. The key to resolving this question is the concept of yi’ush-giving up hope.
Even if one loses an object he retains full ownership of the object. However, if he gives up hope of recovering his object after he became aware that he lost the object, his ownership is weakened. The view of many poskim is that the owner’s ownership is totally relinquished immediately when the owner gives up hope. There are others (Nesivos 37, 13: Chazon Ish Bava Kama 18, 1) who maintain that ownership is only relinquished when someone picks up the lost object after the owner gave up hope of its being returned.
In any case, if the finder picks up the lost object after the owner gave up hope, the finder becomes the new owner of the lost object. However, if the finder picked up the lost object prior to the owner’s giving up hope, he does not become the new owner of the object. Since it still has an owner, change of ownership is not possible.
The Gemara goes even further and says that not only is ownership not transferred immediately if one picks it up before the owner gave up hope, but even if the owner does eventually give up hope, the finder cannot keep the object for himself. The reason for this is the subject of a dispute. The Ramban (Milchamos Bava Metseyo 26B) says the reason is because when the finder picked up the lost object he became a shomeir-a watchman, for the object’s owner i.e. the loser. Since it is being watched for the loser, it is as if the object never left the possession of the loser and yi’ush is only effective once a lost object leaves the loser’s possession. The other approach (Tosafos Bava Kama 66A) is that when the finder picked up the lost object he became obligated to return it to the loser, and the subsequent yi’ush does not affect this obligation.
Thus, we have established that the key factor to consider to answer the first question is whether the loser gave up hope before the finder picked up the lost object.
The Gemara discusses when in general a loser gives up hope of recovering an object that he lost. There are two key factors: one is that the loser has to become aware that he actually lost the object, and the second is that he has to give up hope. The Gemara says that if a person has a siman (a unique identifying feature) on a lost object he does not give up hope of recovering his lost object since he thinks that it will be returned since he can prove that it is his. Therefore, if the money you found has a unique identifying feature you definitely cannot keep it because the owner probably did not give up hope and thus it still belongs to the loser. If the object does not have such a feature, then we have to consider whether we can assume that the loser became aware of his loss before you found the money.
The Gemara (Bava Metsiyo 21B) says that in its time people became aware of losing their money immediately because they constantly touched their pocket to ascertain that they still have their money. The reason was because of the value of money.
There is a major dispute among the poskim if this is still the situation today. Rav Moshe Feinstein wrote (Iggros YD 4, 23, 13) that the rule still applies today. Similarly, there are various anecdotes (cited in Pe’er Hador and other sources) where the Chazon Ish ruled that even nowadays the Gemara’s rule applies. However, Rav Eliashev zatsal is cited in various sources (e.g. Sefer He’oros BM 21B) as having ruled that the principle no longer applies to small amounts of money since people today no longer behave as they did in the time of the Gemara. The Toras Ho’aveido (page 195) reports that Rav Eliashev considered an amount under fifty shekels (about $14) to fall into the category of a small amount.
In conclusion: The answer to your first question is that if the money has a unique identifying feature you definitely must attempt to return it to the loser. If it does not have such a feature and is a significant amount, you can assume that the loser was aware of his loss prior to your finding the object, and you may keep the money since it no longer belongs to the loser.
Your second question is whether if the money left the ownership of the loser you can keep it or perhaps since you found it in the shul, the shul acquired the lost object before you picked it up.
In order to answer this question we have to consider how the shul could have become the owner.
The basis for the shul’s claim to ownership is the kinyan known as chotseir. When an object is situated in a person’s property, the property owner acquires the object. Of course, the object has to be available to be acquired, such as being ownerless. As we discussed earlier, when the owner of a lost object gives up hope, the object becomes available to be acquired. Thus, it would seem that the shul did acquire the lost object since the shul had a kinyan of chotseir before you picked it up.
However, most poskim maintain that the shul did not acquire the lost object. One reason is that Tosafos (Bava Metsiyo 26A) and other Rishonim deduce that the kinyan of chotseir only applies to objects which the owner of the property is destined to find. However, objects which are not destined to be found by the proprietor of the property, for whatever reason, are not acquired by means of the kinyan of chotseir. Since a shul is a public building where many people come and go, there is a very reasonable chance that the object would not be found by the gabbai of the shul. Therefore, the shul did not acquire the money and the question whether you can acquire the money depends only on the answer to your first question.