Pain is one of medicine's greatest mysteries. When farmer John Mitson caught his hand in a baler, he cut off his trapped hand and carried it to a neighbor. "Sheer survival and logic" was how he described it. "And strangely, I didn't feel any pain." How can this be? We're taught that pain is a warning message to be heeded at all costs, yet it can switch off in the most agonizing circumstances or switch on for no apparent reason. Many scientists, philosophers, and laypeople imagine pain to operate like a rigid, simple signaling system, as if a particular injury generates a fixed amount of pain...

Pain is one of medicine's greatest mysteries. When farmer John Mitson caught his hand in a baler, he cut off his trapped hand and carried it to a neighbor. "Sheer survival and logic" was how he described it. "And strangely, I didn't feel any pain." How can this be? We're taught that pain is a warning message to be heeded at all costs, yet it can switch off in the most agonizing circumstances or switch on for no apparent reason. Many scientists, philosophers, and laypeople imagine pain to operate like a rigid, simple signaling system, as if a particular injury generates a fixed amount of pain...