Do you like facts? Some people swear by them. In fact, some people find it impossible to move without first assembling a comprehensive array of unimpeachable “facts” pointing at certainty. Only then will they be prepared to take a few faltering steps forward. After all, facts are written on tablets of stone, yet it appears that not all is well in the world of facts.

You see, while we were all looking away, some people at Harvard University with too much time on their hands worked out that facts are not all that they seem. It appears that facts have a half-life and, just like radioactive isotopes, they tend to degenerate every now and then, only to re-emerge as untruths. For instance, according to those in the know, the half-life of a “fact” in the world of medical science is 40 years, on average. In psychology, the half-life of facts is just five years. In the more nebulous world of social science, around 20 percent of what you know and believe today to be a “fact�