Is the glass half full, half empty, or laced with cyanide? Last week I wrote about “statistics, fast and slow” — the gap between the world as we intuitively perceive it, and the world as described in spreadsheets. Nowhere is this gap more obvious than when we are invited to reflect on whether things are going well, or badly.

With some telling exceptions, the situation is this: the world is getting better in many of the ways that matter, but we simply don’t realise that this is true. Population growth has slowed dramatically. Most of the world’s infants have been vaccinated against at least one disease. Girls are rapidly catching up with boys in their access to education. The world is full of flaws, but progress is not only possible — it is happening.

A new book, Factfulness , by Anna Rosling R?nnlund, Ola Rosling and the late Hans Rosling, describes this knowledge gap, which is at times grotesque: two-thirds of US citizens believe the global proportion of people living in extreme poverty has doubled in the past couple of decades; it has halved. As Hans Rosling used to say, we don’t become this ignorant by accident.