This inquiry has a convoluted beginning. While on holiday in the north of England recently Owen Kelly found himself given a copy of a newspaper called The Light. This seemed at first like the ravings of anti-vaccine conspiracy theorists. On further reading, however, it appeared more interesting than that. It proposed that the germ theory of disease transmission contained fundamental flaws.

In this episode Owen Kelly looks into the history of the controversy, and the competing claims of the germ theory and the terrain theory. He discovers a bad-tempered discussion that obscures as much as it reveals, with both sides offering dubious evidence and drawing unwarranted conclusions.

He asks how this relates to citizen science, and what it means for the informed discussion necessary to any cultural democracy.