Destructive Activities for the Purpose of Shabbos - Shabbos 146a
מקלקל לצורך שבת
Destructive Activities for the Purpose of Shabbos
The mishnah here states that a person may break a jug on Shabbos in order to eat the dates that it contains. By way of explaining this ruling, Rashi writes that destructive activity (viz., breaking the jug) on Shabbos is not prohibited at all. The Rishonim find this assertion difficult, as it seems from several sugyos that there is a rabbinic prohibition even on destructive activities. They therefore write that the rationale underlying this mishnah’s ruling is that it is only for the purpose of Shabbos ( לצורך שבת — in this case, the eating of dates) that destructive activity is permitted (see Rashba and Ran). Other Rishonim suggest that the jug in question here is of a special type: a mustiki - a jar that had previously been broken and then glued together again, and that it is because it is a “disposable” container that it may be broken (see Tosafos and Rosh).
Afikei Yam (vol. 2, 4:6) suggests that Rashi’s position is that Chazal only forbade destructive activity when its constructive analog would constitute a Torah prohibition ( מלאכה גמורה מה"ת ). The constructive analog of the destruction of a jug by breaking it would be breaking the jug in order to make it more useful (for example, if a jug is sealed with a plug, and cannot be uses, breaking off the plug would be constructive breakage). However, in order to violate a Torah prohibition one must break something in order to build something else in its place ( סותר על מנת לבנות ), not in order to improve the existing item. Hence, in our case, in which the breaking has no constructive analog, Chazal allowed the activity. Afikei Yam further notes that according to Rashi, in a case such as ours, which involves breaking vessels, even breaking the vessel in order to build something else in its place would be permitted, as Rashi’s position elsewhere is that there is never any Torah prohibition involved in the construction or destruction of vessels of any sort ( אין בנין וסתירה בכלים ). [Afikei Yam cites several other authorities that seem to be of the same opinion, among them Sefer Yereim, mitzvah #272.]