One of Nicholas Humphrey’s rules about what makes an effective placebo is that there must be some effort, scarcity or expense involved. Folk remedies may be effective placebos simply because the plants needed to make them aren’t all that common. If there is one area that is worthy of future scientific research, this is it. At the moment, we spend many billions of dollars each year trying to improve drugs but almost nothing, as far as I can see, is being spent on the better understanding of placebos – they look too much like alchemy.
