The Subtraction Test
Generate a remove-first option before adding resources
- Difficulty
- Easy
- Time to result
- ~days to results
- Steps
- 5
- Confidence
- 98%
The Subtraction Test corrects a predictable blind spot in problem solving: people tend to add resources even when removal would work better. Easter recounts experiments in which participants could solve a task by adding or subtracting, while subtraction was consistently more efficient; participants nevertheless defaulted to addition. The method makes the neglected half of the option space explicit. First define the result, then generate the solution your mind naturally offers. Before acting, separately ask how the same result could be achieved by removing a step, component, obligation, or resource. Compare the alternatives on effectiveness, time, energy, cost, and complexity. Subtraction is not automatically superior, but requiring a remove-first candidate prevents an additive bias from deciding before the comparison begins.
Origin
Researcher Leidy Klotz noticed the bias while building a crooked Lego bridge with his three-year-old son, Ezra. Klotz searched for blocks to add, while Ezra fixed the bridge by removing blocks from the taller pillar. Later experiments repeatedly reproduced the preference for addition.
Core principles
- 01People preferentially notice additive solutions
- 02Subtraction keeps neglected options visible
- 03Removing can conserve time, energy, and resources
- 04Additive and subtractive options deserve explicit comparison
How to run it
- 1
State the outcome
Describe the problem to solve or the improvement to make without prescribing a method.
Pro tip Use an outcome such as level the bridge rather than an action such as add support.
- 2
Capture the default
Write down the first solution that comes to mind. It will often involve adding money, steps, tools, people, or material.
Watch out Do not implement the first idea before testing subtraction.
- 3
Force a subtractive option
Ask how you could solve or improve the situation by removing something. Generate at least one concrete candidate.
Pro tip Look for removable steps, features, meetings, dependencies, possessions, or constraints.
- 4
Compare resource use
Evaluate additive and subtractive candidates for effectiveness, cost, time, energy, and complexity.
Pro tip Credit subtraction for resources it frees for other uses.
Watch out Do not treat fewer components as proof that the outcome will be adequate.
- 5
Choose on evidence
Select the option that achieves the outcome with the best overall resource trade-off. The test expands consideration; it does not predetermine the answer.
In the wild
Klotz and his son built two pillars with a span resting at an angle because one pillar was taller. Klotz turned to the Lego bin to find pieces to add. His son instead removed blocks from the taller pillar, leveling the bridge while preserving more blocks for the surrounding Lego city.
→ Subtraction solved the problem more efficiently and freed resources for other uses.
A team wants to reduce the time needed to approve a routine request. Before buying another workflow tool, it tests whether removing a redundant approval step achieves the same control with less delay.
→ The team considers a lower-cost, lower-complexity solution that additive thinking would have missed.
Common mistakes
Assuming subtraction always wins
The framework requires considering subtraction, not choosing it when addition produces the better result.
Defining the problem additively
A prompt such as what should we add has already removed subtractive options from consideration.
Ignoring freed resources
A subtractive solution can create additional value by releasing time, energy, money, or materials for other work.
Is it for you?
Best for
Anyone improving a product, process, routine, organization, or physical design under resource constraints.
Not ideal for
It should not force removal when a genuinely missing capability or resource must be added.
From the transcript
“humans are wired to add even when it doesn't make sense we just preferentially Overlook subtraction”
“if you're trying to improve something if you are trying to solve a problem you should probably write down okay how would I solve this…”
“those options are often more efficient they're often a better use of time of energy of resources”
From the episode
Episode 397: Michael Easter on The Comfort Crisis: Is Optimizing Life Making Us Weaker?