put Us-es and Thems together under very narrow circumstances and something sort of resembling that happens, but you can also blow it and worsen things. Some of those effective narrower circumstances: there are roughly equal numbers from each side; everyone’s treated equally and unambiguously; contact is lengthy and on neutral, benevolent territory; there are “superordinate” goals where everyone works together on a task they care about (say, the summer campers turning an overgrown meadow into a soccer field).
