When I was seven years old, I was once reprimanded by my mother for an act of collective brutality in which I had been involved at school.

When I was seven years old, I was once reprimanded by my mother for an
act of collective brutality in which I had been involved at school. A
group of seven-year-olds had been teasing and tormenting a
six-year-old. "It is always so," my mother said. "You do things
together which not one of you would think of doing alone." ...
Wherever one looks in the world of human organization, collective
responsibility brings a lowering of moral standards. The military
establishment is an extreme case, an organization which seems to have
been expressly designed to make it possible for people to do things
together which nobody in his right mind would do alone.
-- Freeman Dyson, "Weapons and Hope"