The placebo effect

Feed a sick man a dummy pill that he thinks will cure him and, often, his health will improve in a similar way to someone taking real drugs. In other words, a bunch of nothing can improve your health. In theory, it could be a powerful treatment technique.

But experiments have shown that the kind of nothing you deliver matters: when placebos are laced with a drug that blocks the effects of morphine, for instance, the effect vanishes. While that proves that the placebo effect is somehow biochemical—and not just a psychological effect—we know practically nothing else about the power of placebo.

It's real, sure. It can help people get better, agreed. But if we're ever to make anything of the much-studied but little-understood effect, we're going to have to unpick how the mind can affect the body's biochemistry—and, right now, nobody knows.