> read /field-guides/5-whys

FIELD GUIDE #001 // ROOT CAUSE

5 WhysDon’t stop at the first plausible why.

5 Whys is a compact way to follow one causal chain from a visible problem toward a condition you can change. The value is not the number five. The value is forcing each “because” to earn its place.

USE WHENA CAUSAL SEQUENCE IS PLAUSIBLE
AVOID WHENYOU NEED TO MAP MANY COMPETING CAUSES
REMEMBERA PLAUSIBLE CHAIN IS NOT YET PROOF

WHAT 5 WHYS IS FOR_

Start with a specific problem and ask why it happened. Then ask why that condition existed. Continue until the chain reaches something operational, systemic or controllable enough to investigate and improve.

CAPYBARA RULE: “Five” is a prompt, not a quota. Stop at three if the chain is already well-supported and actionable. Continue past five if the next link still matters.

RUN IT AS A CAUSAL CHAIN_

01Define the problem. Describe what happened, where and when. Avoid explanations in the problem statement.
02Ask why. Record the most supportable cause of the previous condition, not the most dramatic explanation.
03Check the link. What observation, log, test or witness supports this “because”?
04Continue. Ask why that cause existed. Keep one chain coherent instead of jumping between unrelated branches.
05Stop deliberately. Stop when further “whys” become speculation, leave your sphere of influence, or add no useful control point.

CAPYBARA CASE #001_

The Missing Snacks case follows a simple chain:

PROBLEMWatermelon is missing.
WHY 1A bird ate it.
WHY 2The gate was left open.
WHY 3Closing the gate relied on memory.
WHY 4No self-closing control existed.

The useful shift is from blaming a forgetful person to examining a process that depends on perfect memory. A possible countermeasure is a self-closing gate, but it should still be verified against the actual failure.

COMMON FAILURE MODES_

Stopping at a person

“Because Alex forgot” often describes the last human action, not the condition that made one lapse enough to create the problem. Ask what made the process fragile.

Turning every answer into a fact

If you cannot point to evidence, mark the link as an assumption. A clean-looking chain can still be fiction.

Jumping to the solution

A countermeasure is not proof of a cause. Keep the causal statement and the proposed fix separate.

Forcing one chain onto a multi-cause problem

If several plausible causes compete, move sideways into Fishbone first. Map the possibilities, then return to 5 Whys on the branch that deserves deeper investigation.

USE THE EVIDENCE LEDGER_

Useful evidence is not just “we all think this is what happened.” Record facts separately from assumptions, define tests for uncertain links, and record results. When a link cannot survive that separation, the chain needs work.

GOOD STOPPING QUESTION: If this condition changed, would the problem become less likely — and do we have evidence that the condition actually existed?

OPEN 5 WHYS →USE IN AN INVESTIGATION →