Stephen Sackur speaks to the renowned Harvard academic James Robinson. In a recent book, written together with Daron Acemoglu, he tries to answer one of the most basic questions of global economics and politics: why do some nations thrive while others fail? What does Norway have that Mali lacks?

There are of course multiple answers based on physical geography, resources and cultural differences, but James Robinson is adamant one factor determines economic success much more than all others: the development of resilient, inclusive political institutions.

Put crudely, the idea is political freedom begets prosperity - but is that always true?

(Image: James Robinson)