http://revach.net/article.php?id=444

Section:  Avodah   Category: Pirkei Avos
What's Mine Is Your, What's Yours Is Mine. Is It a Good Thing?

If someone is happy to share his possessions and enjoy other peoples possessions as well, the mishna calls this person an Am Ha'aretz. The Bartenura explains that Am Ha'aretz is a term used for an ignorant person, who in this case thinks he is promoting good social behavior but is ignorant of the fact that the Pasuk says "Sonei Matanos Yichye"; He who hates present will live.

The Maharam Shick argues and says that since sometimes he is on the giving end and sometimes on the receiving end, his receiving is not considered a gift. Moreover he is promoting positive social interaction because sometimes one is in need and someone else has extra and sometime the reverse. By giving and taking a social group can help each other navigate their individual troughs and peeks.

Therefore he says that Sheli Shelach, Shelach Sheli is definitely a wonderful midah worthy of praise. He explains the term Am Ha'aretz to mean a person who for him the world was created, or similarly, a person who will inherit the earth through his mitzva of sharing. He ends by saying that this midah will end Sinas Chinam and bring Moshiach.