And the latest research holds out the promise of drugs to help forget traumatic memories, or even to stay devoted to our sexual partners. Many people—notably some religious leaders, doctors, scientists, politicians and philosophers—have misgivings about much of this. But when they spell out their qualms, their reasoning is often shakier than it first appears. Nonetheless, this is not a debate we can ignore. What scientists are now discovering about memory presents us with an interesting set of dilemmas.