# When Plans Surprise Us - Link: https://clearingintheforest.org/when-plans-surprise-us/ - Published: 2026-10-20T23:46:26+00:00 - Author: Saal_clearingforest [ ๐ŸŒฒ A clearing in the forest ](https://clearingintheforest.org/) [ All pages ](https://clearingintheforest.org/?page_id=267#pages) # 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. I planned something HUGE all in one go (a party, a game, a project) and it fell apart. Something got easier or cheaper, so I ended up doing it _way_ more. A new rule at school made a new problem nobody expected. **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 (1925โ€“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. Floors: 0 / 12 ### Gall's other rules. Tap a card to flip it. Systems fight backtap A new system creates new problems of its own. A queue-number machine at the doctor's makes a new job: fixing the machine. Systems look after themselvestap Over time, keeping the system going becomes its real job. A homework-tracking form can end up taking longer than the homework. Systems fool youtap What the system _reports_ isn't what's really happening. A spreadsheet saying "all pupils happy" doesn't make it so. Systems fail in surprising waystap It almost never breaks where you were watching. It breaks somewhere you never thought to look. 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**. **Efficiency: 1ร—** (2ร— means each use needs half as much) 100 Cost of one use 100 How much people use it 100 TOTAL used up ### 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)? Story 1 of 7 ยท Score 0 ## Can you explain it, friend? Tick each one you could explain to a friend in one sentence. **Gall's Law:** things that work start small and grow. Giant plans built in one go break. **Systems fight back:** fixing one problem with a new system often makes new problems. **Jevons paradox:** make something cheaper to use, and people may use so much more that the total goes up. **The catch:** Jevons only happens when people want lots more. Usually efficiency does save. **The link:** both men saw that the world reacts to our plans in ways we don't expect. ๐ŸŽ‰ **You, you now think like a systems detective.** Next time you start something big, start small. Next time something gets cheaper, ask: "Will we just use more?" ### 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):9โ€“21] * [Ref: Sorrell S. Jevons' Paradox revisited. _Energy Policy_. 2009;37(4):1456โ€“ 1469] Written by **Dr Saal Seneviratne**, Consultant Psychiatrist at [The Burlington Clinic](https://www.theburlingtonclinic.com), London ยท Last reviewed 21 October 2026 ยท [About these pages](https://clearingintheforest.org/about/)