We learn in the Mishna that performing half of the melacha of carrying is an issur derabanan but not min hatorah. Why is it not assur min hatorah, since we know that even a ‘chatzi shiur assur min hatorah’ (i.e. eating half a kezayis of prohibited food)?
The Gemara tells us that a person may not transgress in order to prevent his friend from sinning. This implies that one may do so for his own benefit. Since we know that ‘kol yisrael areivin ze lazeh’ and that all Jews are responsible for one another in the same way as they are responsible for themselves, why then would he not be permitted to do for a friend exactly as he would for himself?
Rashi (6b D”H kma”l) explains that the term ‘reshus hayachid gemura’ indicates that according to the Rabbanan a Reshus Hayachid requires to be completely enclosed from all sides. Rashi in Eruvin (11b D”H lizrok) says that a Reshus Hayachid requires only three walls. How can we resolve both Rashi’s?
We learn that a house that is less than ten tefachim high is considered to be a Carmelis. But if what defines a Reshus Hayachid is a self-contained area (which is separated from Reshus Harabim through partitions) why would this fully enclosed area not constitute a Reshus Hayachid?
The Gemara concludes that a privately owned courtyard which is used as a public walk-through is considered a Reshus Harabim (see Tosfos D”H Yehoshua). How can this be derived from the Midbar which featured only a publicly owned Reshus Harabim?