Reverse Thinking
Invert the apparent action to reveal a safer or simpler solution
- Difficulty
- Easy
- Time to result
- ~days to results
- Steps
- 5
- Confidence
- 98%
Reverse Thinking solves a constrained problem by asking what the apparent action is doing in the opposite direction. A man digging in a locked room is not only making a hole; he is building a mound that can reach a skylight. Collecting laundry can become moving the hamper to the clothes rather than carrying repeated armloads to the hamper. Elevator brakes can be designed so electricity releases them, making braking—not free movement—the default during a power failure. The method exposes assumptions about what must move, which direction matters, and which state requires energy. After identifying the inversion, test whether it preserves the desired outcome and improves effort or safety. Inversion is a generator of alternatives, not a command to reverse every process.
Origin
A.J. Jacobs introduces reverse thinking through a lateral-thinking riddle about a trapped man whose digging creates the mound he needs to reach a skylight.
Core principles
- 01An action also creates its opposite effect
- 02Reversing direction can eliminate unnecessary movement
- 03Safe systems can make protection the default state
- 04Hidden assumptions often define the apparent constraint
How to run it
- 1
State the obvious action
Describe what appears to be moving, changing, or consuming effort and what result it is supposed to create.
Pro tip Use concrete nouns and directions so hidden assumptions are easier to see.
- 2
Name the inverse effect
Ask what opposite state or structure the same action creates at the same time.
Pro tip For every removal, look for an accumulation; for every release, look for a default restraint.
Watch out Do not rely on wordplay when the physical mechanism does not support it.
- 3
Swap the mover
Consider bringing the destination to the objects, moving the constraint, or reversing which state requires energy.
Pro tip Ask, “What if the other thing moved instead?”
- 4
Test the inversion
Verify that the reversed arrangement reaches the same goal with less effort or a safer failure mode.
Pro tip Test failure conditions as well as normal operation.
Watch out A clever inversion is not useful if it shifts risk somewhere less visible.
- 5
Adopt or discard
Use the inversion when it improves the full system; otherwise retain the original method and the insight gained.
Pro tip Document the assumption that changed so the pattern can transfer to future problems.
In the wild
In Jacobs's riddle, a trapped man cannot tunnel through the cement walls, but digging also piles up dirt. He climbs the resulting mound to reach the skylight.
→ Recognizing the opposite effect of digging resolves the apparent impossibility.
Rather than collect repeated armloads of his sons' clothes and carry them to a bedroom hamper, Jacobs moves the hamper through the house and puts the clothes directly into it.
→ Reversing which object moves reduces the number of trips.
Jacobs learns that elevator brakes are normally clamped and electric current releases them. When power fails, the brakes therefore remain engaged rather than requiring electricity to activate.
→ The reversed default creates a fail-safe response to power loss.
Common mistakes
Reversing without a mechanism
Inversion must change a real physical or procedural relationship, not merely rename the original action.
Ignoring the failure state
A process that works in normal conditions may become worse when power, attention, or another dependency disappears.
Treating inversion as mandatory
Reverse thinking generates a candidate solution that still needs comparison with the conventional design.
Is it for you?
Best for
It is best for logistics, process design, safety systems, and constrained problems where the obvious action has an overlooked inverse.
Not ideal for
It is not ideal when reversing the action creates untested safety, legal, or physical risks.
From the transcript
“the idea is to reverse your thinking to think upside down to think totally differently”
“instead of focusing on the fact that he's digging whole what what else is he doing he's doing the opposite he's building a mountain”
“bring the hamper to the clothes”
From the episode
#588: A.J. Jacobs — How to Be Less Furious and More Curious