Rabboti,
The last several dapim discuss amounts of water, oil and other liquids that are mechayev a chatas if carried on Shabbos. Yet there seems to be a difference made for what purpose the carrier is taking these liquids out. Some of them are deemed insignificant if they are too small for the intended purpose. In fact, there are various views in the gemara about how much water etc is needed for each purpose.
Doesn't the gemara usually say in such cases: "Im keyn nasata d'varecha l'shiurim," i.e. if this is so then it's not one din for everyone but each person has his own shiur, an untenable situation. Yet the gemara does not ask this here.
Why not?
Kol tuv,
Sam Kosofsky
The question of "Nasata Devarecha l'Shi'urin" is usually asked when the Gemara gives a generic description of an amount of time. For example, the Gemara in Chulin (32a) says that the amount called "K'dei Shechitah" is the amount of time it takes for one to bring another animal and slaughter it. The Gemara asks, "Nasata Devarecha l'Shi'urin," meaning that this is not a given amount of time which can be determined, as it varies depending on the proximity of the next available animal.
These Gemaros in Shabbos generally discuss amounts (and arguments) regarding the minimum amount of an item which is considered Chashuv to be considered Hotza'ah. The Mishna (75b) and Abaye's statement (78a) give guidelines as to how these general Shiurim can be determined, though it is clear from the Mishna itself that a person can create his own personal Chashivus, and hence his own personal amount (as this is Chashuv to him). Abaye's position (78a, according to RASHI DH "b'Glila") is that a city can also create its personal Chashivus.
All of the arguments center on the determining factor of what is the minimum possible amount which is Chashuv. This is why the Gemara does not ask "Nasata Devarecha l'Shi'urin."
Kol Tuv,
Yaakov Montrose