Oxford philosopher Jonathan Glover came up with this vegetarian allegory. It was published in Proceedings of the Aristotelian Society in 1975. Here’s Peter Singer’s reiteration, as published in his essay A Vegetarian Philosophy.
“In a village, 100 people are about to eat lunch. Each has a bowl containing 100 beans. Suddenly, 100 hungry bandits swoop down on the village. Each bandit takes the contents of the bowl of one villager, eats it, and gallops off. Next week, the bandits plan to do it again, but one of their number is afflicted by doubts about whether it is right to steal from the poor. These doubts are set to rest by another of their number who proposes that each bandit, instead of eating the entire contents of the bowl of one villager, should take one bean from every villager’s bowl. Since the loss of one bean cannot make a perceptible difference to any villager, no bandit will have harmed anyone. The bandits follow this plan, each taking a solitary bean from 100 bowls. The villagers are just as hungry as they were the previous week, but the bandits can all sleep well on their full stomachs, knowing that none of them has harmed anyone.”
“We are each responsible for a share of the harms we collectively cause, even if each of us makes no perceptible difference.” - Peter Singer, A Vegetarian Philosophy