A detailed look at how Swedes, and now many other nationalities, got caught up in the pseudo-scientific Colour Theory of personality analysis put forward in Thomas Eriksen’s Surrounded by Idiots.

Despite the use of colours, it turned out that the “Surrounded by …” books were not based on Myers-Brigg. Instead, they built on another personality theory, the so-called DiSC model. The most noteworthy outcome of a search through the academic literature on this model was that, despite the fact that the test had been around for fifty years, there was in principle no research on whether or not it worked.

Despite Eriksen having no qualifications, and the theory itself having lain dormant since the 50s, with no supporting research, the book has gone on to sell more than two million copies world-wide, simply because no-one bothered to factcheck when it first came out.

In the age when anyone can publish their views online, the very institutions which we are meant to trust — -publishers, broadcasters and newspaper editors — -have to fight harder than ever to maintain their own trustworthiness. If they lose that trust then the very existence of democracy and the open society is at risk.