Possibilian Inquiry Method
Keep multiple explanations open, then let evidence narrow the field
- Difficulty
- Moderate
- Time to result
- ~weeks to results
- Steps
- 5
- Confidence
- 97%
The Possibilian Inquiry Method is an active approach to uncertainty. Instead of committing to an inherited answer, claiming nothing meaningful exists, or stopping at 'I don't know,' it maps the possibility space and investigates it. First state the unresolved question, then place multiple hypotheses on the table. Define observations or experiments that can discriminate among them, gather evidence carefully, and update how much weight each explanation deserves. Some possibilities will be ruled out; others will gain support; new evidence may reveal options that were not initially imagined. The output is disciplined openness: intellectual humility paired with a concrete search process, rather than certainty without evidence or uncertainty without action.
Origin
Eagleman coined Possibilianism to describe a position between inherited religious certainty, strict atheism, and passive agnosticism, then presented it in a TEDx talk.
Core principles
- 01Mystery warrants inquiry rather than premature certainty
- 02Multiple hypotheses should begin on the table
- 03Careful experiments protect against self-deception
- 04Evidence can rule possibilities in or out
- 05Intellectual humility is active exploration, not passive indecision
How to run it
- 1
Define the unknown
Write the question and separate what is observed from what is assumed. Acknowledge where current knowledge ends.
Pro tip Phrase the problem so more than one answer can survive initially.
Watch out Do not use mystery as evidence for a preferred explanation.
- 2
Open the possibility space
Generate multiple explanations, including ones outside your inherited beliefs. Keep each specific enough to produce different predictions.
Pro tip Add a hypothesis that would surprise you if supported.
Watch out Not every imaginable claim is equally plausible.
- 3
Design discriminating tests
Specify evidence that would strengthen or weaken each hypothesis. Prefer observations that produce different expected results across the candidates.
Pro tip Write the update rule before seeing the evidence.
Watch out A test that every hypothesis can explain does not narrow the field.
- 4
Gather evidence carefully
Run the experiment or collect observations while guarding against self-deception. Record contradictory evidence rather than explaining it away.
Watch out Do not promote conviction merely because a story is culturally familiar.
- 5
Reweight and continue
Rule out unsupported explanations, increase confidence in supported ones, and preserve genuine unknowns. Repeat when new evidence opens another part of the possibility space.
Pro tip Report confidence, not a forced binary conclusion.
In the wild
Eagleman contrasts a claim that Earth is 6,000 years old with evidence of Japanese pottery from 7,000 years ago and cave writing from 30,000 years ago. The observations rule against that particular historical account without pretending science has solved every mystery.
→ One hypothesis is rejected while the broader possibility space remains open to investigation.
Illustrative example: a founder considers price, onboarding friction, and weak demand as competing explanations for falling activation. Before changing the product, the founder defines distinct evidence for each and runs interviews plus an onboarding test.
→ The team acts on discriminating evidence rather than its favorite story.
Common mistakes
Calling indecision open-mindedness
Possibilianism is active exploration of alternatives, not merely saying that the answer is unknown.
Giving every claim equal weight
Hypotheses begin on the table, but evidence should rule against explanations that conflict with observation.
Claiming science knows everything
The method uses science to investigate mystery without pretending current science has a complete account.
Is it for you?
Best for
It is best for complex questions where several explanations remain plausible and testable.
Not ideal for
It is not ideal when established evidence has already decisively ruled out a claim.
From the transcript
“We're not gonna fool ourselves into, into believing something unless there's evidence that supports it.”
“I'm interested in the possibility space.”
“But, but the idea is the scientific temperament always allows lots of hypotheses on the table and then we gather evidence to weigh in favor…”
From the episode
David Eagleman: What Neuroscience Reveals About Your Brain and Human Nature
David Eagleman