When a Rat’s Tail Became the Product
A bounty is meant to make a costly problem worth solving: the city pays, and hunters do the work of removing rats. But the reward only works if the thing being paid for reliably proves that the problem has been reduced. In this case, payment depended on producing a rat tail—not on showing that a rat had been killed or removed.
That small design choice changed the hunters’ incentives. A dead rat could provide one tail and one payment. A living rat could provide a tail, be released, and later produce more rats—and therefore more tails to collect. The hunter could earn repeatedly from the same animal’s descendants while the city’s underlying problem grew.
The Measure Replaced the Goal
This is a classic incentive trap: people respond to what a system rewards, even when it is only a proxy for what the system is meant to achieve. The city wanted fewer rats, but it counted tails. Once a tail could be separated from the outcome it was supposed to represent, the bounty rewarded evidence of activity rather than successful removal.
The scheme did not merely fail to eliminate the rats. It could make continued breeding financially useful to the people paid to catch them. That is the danger in a poorly designed bounty: the public can end up paying for a visible sign of progress while the actual problem becomes more profitable to sustain.
