We live in post-truth times. Fake news is everywhere; if we’re not reading it, we're seeing Trump accusing reputable news outlets of it.
Instead of laughing about the ridiculousness though, a prominent historian thinks we should be very worried indeed.
Timothy Snyder, a professor of European history at Yale, wrote a very long Facebook post after Donald Trump won the US election last November.
He warned Americans that they need to learn the lessons of Europeans who’ve lived through Nazism, fascism and communism.
And now, Snyder is bringing out a book, On tyranny, with the same message.
He told Vox:
The Europeans who saw their regimes change were not necessarily less wise than we are. I'd be tempted to say they're wiser, in fact.
I think we have a lot of good attributes in our society, in our political system, but also we've been lucky a lot of the time.
It's important to be humble and to realise that past success is no guarantee of future returns.
We think that because we're America, everything will work itself out.
But the most disturbing thing he has to say?
Post-truth is pre-fascism. To abandon facts is to abandon freedom.
So what happens next is going to depend on us.