Science is based on fact. Isn't it? Karl Popper believed that human knowledge progresses through 'falsification'. A theory or idea shouldn't be described as scientific unless it could, in principle, be proven false.

Narrated by Aidan Turner. Scripted by Nigel Warburton.

From the BBC Radio 4 series about life's big questions A History of Ideas.

This project is from the BBC in partnership with The Open University, the animations were created by Cognitive.