When economist Noreena Hertz became very ill she confronted a difficult question: who should she trust?

The answer was much more complicated than it first appeared and her quest to find out more about her treatment led her to a deep scepticism about expertise.

Four Thought is a series of thought-provoking talks in which speakers air their thinking on the trends, ideas, interests and passions that affect culture and society in front of a live audience.

Presenter: Ben Hammersley