As we have seen, even in a place with no eruv, one may carry items needed for food preparation from one domain to another. Once carrying is permitted for okhel nefesh, it is permitted for other reasons as well, as long as it contributes to the enjoyment of Yom Tov. Thus, one may carry a watch in his pocket so that he will know what time it is or sunglasses in his pocket so he will have them if necessary. A woman may go out to the public domain wearing jewelry that she plans to show her friends.
Carrying is also permitted if it will contribute to spiritual enjoyment. One may carry a lulav in order to fulfill the mitzva of shaking it. He may even carry in order to enhance a mitzva. For example, one who already shook his lulav before praying may still carry it to the synagogue in order to shake it during the recitation of Hallel. One may also carry a shofar on Rosh Ha-shana or a lulav on Sukkot to allow women to fulfill these mitzvot (SAH 589:2; SSK ch. 20 n. 5, disagreeing with Sha’agat Aryeh §§106-107).
Those going on an outing with a baby may put the baby in a carriage and take along a bottle, a pacifier, and toys that the child enjoys. They may also take clothing that the baby might need, such as a sweater in case it gets cold out, or a change of clothing in case the baby gets dirty.
An adult may also carry an item of clothing that he might need, such as a sweater. But he may not take clothing that he will not need. One may also take tissues that might be needed.
The poskim disagree about the case where one needs a particular key which is on a key ring with other keys that serve no Yom Tov need. Some maintain that he must detach the needed key, as it is the only one he is permitted to carry. Others say he may carry the entire key ring. Since this disagreement pertains to a rabbinic law, the halakha follows the lenient position.
. We said above that when there is a chance that an item will be needed on Yom Tov, it may be carried, but if there is no chance it will be needed, it may not (MB 518:10; SSK 19:2). Does marbeh be-shi’urim apply? May one increase quantities? As we have seen, it is permissible to add extra water to a pot before placing it on the fire (3:4 above). Similarly, one who needs three tissues may slip an extra one into his pocket. It could be argued that the case of one key needed from a key ring is similar. In fact, some do maintain this and thus permit taking the whole key ring. Nevertheless, others argue that this is not comparable to the case in which marbeh be-shi’urim is permitted: water which is being heated up could be used on Yom Tov, while the additional keys on the key ring will definitely not be used on Yom Tov (Igrot Moshe OḤ 5:35; Hilkhot Mo’adim 5:9). A middle position maintains that while one may not add unnecessary keys to a key ring (just as one may not add water to the pot once it is on the fire), as long as they are already on the key ring, one may take the whole ring without removing the extra keys (SSK ch. 20 n. 14; this position is also attributed to R. Shlomo Zalman Auerbach and R. Yosef Shalom Elyashiv). The halakha follows the lenient position. There are a number of reasons for this. First, the rationale seems correct. Second, the disagreement is on the rabbinic level; the Hotza’ah in this case is a melakha she-eina tzerikha le-gufa, which according to most poskim is rabbinic. Third, according to Rashi and others (see next note), unnecessary carrying is not prohibited at all (or is prohibited only rabbinically). Fourth, many maintain that nowadays there is no such thing as a reshut ha-rabim as defined by Torah law (and thus an eruv is sufficient to permit carrying). Since most of our communities have an eruv, even the stringent position would admit that the prohibition is rabbinic (Peninei Halakha:Shabbat 21:9 and n. 9). See Harḥavot 6:2:2-3. A car key is muktzeh, so the leniency to carry extra keys would apply only if the other keys on the ring are more significant than the car key.
Let us say one needs to carry a diaper bag or any bag that contains baby paraphernalia as well as muktzeh items. According to the lenient position he may do so, even though he will also be moving the muktzeh, as long as the non-muktzeh items are more important. Since the items were not placed in the bag on Yom Tov, it is considered marbeh be-shi’urim and permitted.