ABSTRACT
You are offered money to accept a mildly painful stimulus, and more money each time the stimulus is increased. There is a degree of pain from the stimulus so great no amount of money would induce you to accept it. But each single increment is undetectable. So there is no point at which it is rational for you to call a halt: you will always find it advantageous to accept the next degree of pain for more money, since it will be indistinguishable from the last.
