I grew up with the idea that there are developed countries and developing countries. There was the ‘rich’ world and the 'poor’ world. I didn’t actively consider it, it’s just always been there. And it’s wrong.
Hans Rosling, in his excellent book Factfulness, shows that wealthier countries tend to have smaller families and a low child mortality rate, whereas poorer countries were more likely to have larger families and a high child mortality rate. Plotting the spread of countries in 1965 gives a reasonable approximation of a cluster of 'developed’ countries with small families where most children live, and 'developing’ countries with larger families where more children die. But that’s in 1965.
The world has changed a lot since then and now that model of dividing up the world into two buckets just doesn’t hold true with the data any more. Most people in the world are somewhere in the middle.
And more useful than dismantling my worldview is providing a new model to replace it with. A model with 4 income levels instead of 2 and the number of billions of people who currently live in each level. It’s a model with most people somewhere in the middle.
For more, check out the Factfulness book, or Gapminder. And you could do much worse than watch Hans’ entertaining TED talk: the best stats you’ve ever seen.
Also see: The destiny instinct.