51 Percent Reversible Decision Rule
Act once evidence slightly favours a reversible choice, then learn
- Difficulty
- Easy
- Time to result
- ~days to results
- Steps
- 6
- Confidence
- 98%
Bartlett presents a rule he says he took from hearing Barack Obama discuss presidential decisions: complete certainty is often unavailable, so once the evidence makes one option slightly more likely to be right, act and accept that the choice used the best information available. Bartlett adds an important practical mechanism for ordinary decisions: procrastination has its own cost, while many business choices can be reversed after new evidence arrives. Apply the rule by defining the choice, classifying its reversibility and downside, gathering material facts, and estimating whether one option is more likely than not to be right. Compare the risk of acting with the accumulating cost of delay. If the choice is genuinely reversible and clears the threshold, act and schedule a review. This is Bartlett's interpretation and decision heuristic, not a verified quotation or universal rule from Obama.
Origin
Extracted from The Diary of a CEO. Steven Bartlett says he adapted the rule after hearing Barack Obama discuss making high-stakes decisions without complete information; the episode does not verify Obama's exact wording.
Core principles
- 01Many consequential choices never reach complete certainty
- 02Delay has a cost that belongs in the decision
- 03A slight evidence advantage can justify a reversible action
- 04Peace comes from judging the process by the information available at the time
- 05New evidence can support reversal or correction
How to run it
- 1
Define the Choice
State the options and the decision deadline. Name what continuing not to decide will cost.
Pro tip Include delay as an option with consequences, not as a neutral default.
- 2
Classify Reversibility
Assess whether the choice can be corrected, reversed, or limited after new evidence appears. Identify the worst credible downside.
Pro tip Reduce the first move's scope if that makes it safely reversible.
Watch out Do not apply a thin confidence threshold to irreversible or life-critical choices.
- 3
Gather Material Evidence
Collect the information that could reasonably change the decision now. Stop when further research is unlikely to alter which option leads.
Pro tip Distinguish missing material facts from the emotional wish for certainty.
- 4
Find the Slight Lead
Ask whether one reversible option is more likely than not to be right. Use 51 percent as a metaphor for a slight evidence advantage, not false numerical precision.
Pro tip Write why the leading option leads before acting.
- 5
Compare the Delay Cost
Estimate what another week, month, or year of indecision would forfeit. Act when the reversible choice leads and waiting is more damaging than learning through action.
Pro tip Make the cost of continued rumination explicit.
- 6
Act and Review
Make the decision, document the information used, and set a date or signal for review. Correct course if later evidence shows the first choice was wrong.
Pro tip Judge the original decision by its process, not only by hindsight.
Watch out Reversibility still carries transition and relationship costs.
In the wild
Humes says Bartlett's account of the 51 percent idea reached her when she was considering self-management. She called her management team the next day. Delivering the decision felt emotionally difficult because she did not want to upset people, but the rest of the change felt like a weight had lifted.
→ She took control of her management rather than continuing to delay a decision she already believed was right.
Illustrative example: a team has enough customer evidence to prefer one of two prices but cannot prove the answer in advance. Because the test is limited to new customers for one month, it acts on the slight lead and schedules a review instead of researching indefinitely.
→ Real behaviour supplies evidence while the downside remains bounded and reversible.
Common mistakes
Using 51 Percent for Irreversible Harm
Bartlett discusses soldiers' lives in recounting Obama's dilemma, but that presidential story is not a safe template for ordinary people to lower safeguards on medical, legal, or life-critical decisions.
Inventing Numerical Certainty
The figure expresses more-likely-than-not confidence; it does not make a subjective estimate mathematically precise.
Ignoring the Cost of Reversal
A reversible decision can still upset people or consume time. Bound and acknowledge those costs before acting.
Is it for you?
Best for
It is best for reversible business, career, and relationship choices where material information has been gathered but uncertainty remains.
Not ideal for
It is not ideal for irreversible, life-critical, medical, legal, safety, or high-downside decisions where a slim confidence margin is inadequate.
From the transcript
“you're never going to get to 100 certainty”
“once you get to like 51 certainty on your decision, then make it”
“the procrastination of the decision ends up costing you more in the long term”
From the episode
Rochelle Humes: Learning To Be At Peace With Uncertainty