Facebook facilitated the destabilising of American democracy

Facebook chief Mark Zuckerberg is, at 32, a billionaire and one of the most powerful men in the world.

The social media tycoon has just posted a 5,700-word manifesto that overflows with high-minded good intentions and almost endless possibility about improving the lot of humanity.

It may seem churlish to respond with, at best, guarded enthusiasm but any welcome must be tempered by the role Facebook plays in our world.