When plans surprise us
Two grown-ups. Two big ideas. Both about why clever plans go wrong.
One was a children's doctor. One was a coal-counting economist from Liverpool. They were born 90 years apart and never met. They spotted the same kind of trick that the world plays on planners.
First, what should I call you?
Has this ever happened to you? Tick any that are true.
Then you've already met both ideas. The first and third boxes are John Gall. The second box is William Jevons. Let's meet them.
Meet idea #1
John Gall, the children's doctor
John Gall (1925–2014) was a paediatrician, which means a doctor for children. He worked in Ann Arbor, Michigan, in the USA, and taught at the University of Michigan.
Over many years he watched hospitals, schools and governments launch big new plans. He noticed they kept going wrong in the same ways.
In 1975 he wrote a funny book about it called Systemantics. It was meant as a joke. Then people realised it was true.
Gall's Law: every big system that works started as a small system that worked. A big system designed all at once, from scratch, never works. You can't patch it. You have to start again, small.
Try it, builder: build a 12-floor tower
Left side: the Big Plan. Build it all at once. Right side: the Gall way. Add one floor, check it holds, then add the next.
Gall's other rules. Tap a card to flip it.
Meet idea #2
William Jevons, the coal detective
William Stanley Jevons was born in Liverpool in 1835. At 19 he sailed to Australia to test the metal in coins at the new Sydney Mint. Back in England he became an economist: someone who studies how people use money and things.
In Victorian Britain everything ran on coal: trains, factories, ships. James Watt's improved steam engine did the same work using much less coal. Everyone expected Britain to burn less coal.
In 1865, aged 29, Jevons wrote The Coal Question and said the opposite would happen. He was right. Coal use went up and up.
Jevons paradox: make something more efficient, so each use costs less, and people may use so much more of it that the total goes up, not down.
In his own words (1865): "It is wholly a confusion of ideas to suppose that the economical use of fuel is equivalent to a diminished consumption. The very contrary is the truth."
The Efficiency Machine
Pick a thing. Then drag the slider to make it more efficient. Watch what happens to the total.
The honest bit
Jevons paradox is not a law. It only bites when people want lots more of something once it gets cheaper. Nobody buys five fridges because fridges got efficient. So most of the time, efficiency really does save stuff. Sometimes it doesn't. Try all three buttons to see the difference.
Gall or Jevons? You decide, detective
Read each story. Is it a Gall (big plan built all at once, or a system causing its own trouble) or a Jevons (cheaper or easier, so used much more)?
Can you explain it, friend?
Tick each one you could explain to a friend in one sentence.
Your own challenge
Think of something you want to make: a song, a game, a club, a YouTube channel. What is the tiniest version that works? Write it here (it only stays on this device).
Where this comes from (for grown-ups)
- [Ref: Gall J. Systemantics: How Systems Work and Especially How They Fail. 1975]
- [Ref: Gall J. The Systems Bible. 3rd ed. General Systemantics Press; 2002]
- [Ref: Jevons WS. The Coal Question. London: Macmillan; 1865, ch. VII]
- [Ref: Alcott B. Jevons' paradox. Ecological Economics. 2005;54(1):9–21]
- [Ref: Sorrell S. Jevons' Paradox revisited. Energy Policy. 2009;37(4):1456–1469]