Fifty Inventions That Shaped the Modern Economy

by Tim Harford

In exam halls, when the temperature exceeds the low seventies, students start to score lower on math tests.

AC

Many people are nervous of elevators, yet they are safe—at least ten times safer than escalators.

Elevator

The world makes so much plastic, it consumes about 8 percent of oil production—half for raw material that goes into the plastic itself, half for the energy required to make it.

Oil used in plastic making

get it right, and the results can be impressive. In Ghana, farmers with a clearer right to transfer their property to others invested more in their land.9 Around the globe, the World Bank has found, after controlling for income and economic growth, the countries with simpler, quicker property registries also had less corruption, less gray-market activity, more credit, and more private investment.10

Property registry

The challenge is that public sanitation isn’t something the market necessarily provides. Toilets cost money, but defecating in the street is free. If I install a toilet, I bear all the costs, while the benefits of the cleaner street are felt by everyone. In economic parlance, that’s what is known as a positive externality—and goods that have positive externalities tend to be bought at a slower pace than society, as a whole, would prefer.

Positive externality