Possibilityism
Hold the weight of evidence, and refuse to commit to certainty you don't need.
- Difficulty
- Easy
- Time to result
- ~ongoing to results
- Steps
- 6
- Confidence
- 92%
Possibilityism is a movement Eagleman proposed years ago and describes as still moving around the planet. The idea is straightforward: avoid committing to something with certainty if you don't need to. He frames it as simply an expression of the scientific temperament — what we can have is the weight of evidence at any given time, which lets us say that this is supported more than that, so we will provisionally believe it, without pretending certainty when we don't have enough data. The origin was walking into a bookstore around the time Sapiens came out and finding a front table staged as a battle between two piles: religious fundamentalists on one side, neo-atheists on the other. Eagleman's objection is to the staging itself. His read of Sapiens is that it's all about shining a flashlight around the possibility space — make up forty stories, then make up four hundred more. He applies the same discipline to his own field: asked whether consciousness is emergent or fundamental, he answers that there is no way to know, and that all the data we have is consistent with either. He also applies it asymmetrically and honestly: we have enough data to know the biblical stories are made up and wrong in a thousand ways, but nowhere near enough to conclude there is nothing interesting in the cosmos besides us. Tim's practical corollary is that he back-channel-references people by counting low-conviction statements: someone who makes almost none makes him nervous.
Origin
Eagleman proposed possibilityism after seeing a bookstore front table staged as a war between religious fundamentalists and neo-atheists, and recognising that both piles were pretending to certainty the data does not support.
Core principles
- 01Certainty is a position you adopt, not a state the evidence forces on you, so it can be declined.
- 02The scientific temperament is provisional belief proportional to the weight of evidence, not the absence of belief.
- 03Science is the only human enterprise willing to knock down its own walls; everything else is about defending a throne.
- 04Some questions genuinely have no data, and those are exactly the ones where possibilityism does the most work.
- 05Rejecting one bad answer does not license certainty about its opposite.
- 06Frequent high-conviction statements are a negative signal about a person, not a positive one.
How to run it
- 1
Locate the actual question
State the open question precisely and separately from the camps that have formed around it — for example, is consciousness emergent or fundamental, rather than which side of the debate you are on.
Pro tip If the question only exists as a two-pile bookstore table, the framing is the first thing to reject.
Watch out Adopting an existing camp's phrasing usually smuggles in its assumptions.
- 2
Inventory the evidence honestly
Say exactly what data exists. Eagleman notes that damaging the brain changes consciousness, but that this only shows physical integrity is necessary — it does not discriminate between emergence and panpsychism.
Pro tip Ask what each piece of evidence rules out, which is usually much less than what people claim it proves.
Watch out Evidence consistent with both hypotheses is not evidence for the one you prefer.
- 3
Open the possibility space
Generate many candidate explanations rather than two. Eagleman's model is making up forty stories and knowing you could make up four hundred more.
Pro tip Sum itself is forty tales of the afterlife — the book is possibilityism executed as literature.
Watch out A binary framing is the most common way a possibility space gets illegitimately closed.
- 4
Assign provisional weights
Say which possibilities the evidence supports more than others, and hold those beliefs explicitly as provisional rather than settled.
Pro tip Phrase conclusions as 'this is supported more than that, for now' — the phrasing itself keeps the question open.
Watch out Provisional does not mean weightless; refusing to rank at all is relativism, which Eagleman and Tim both reject.
- 5
Say 'I don't know' when true
Practise stating uncertainty plainly. Eagleman says that as you get older and more mature as a scientist you feel comfortable saying you don't know, and that there is no need to pretend certainty.
Pro tip Follow it immediately with what would resolve it — we'll do experiments, we'll figure it out.
Watch out Saying 'I don't know' without proposing a path to knowing reads as disengagement rather than rigour.
- 6
Audit conviction, in others and yourself
Use the ratio of high- to low-conviction statements as a diagnostic. Tim's back-channel reference on a very smart person was that almost no low-conviction statements made him nervous.
Pro tip Track your own ratio over a week of conversations; it is easier to see in yourself once you have counted it in someone else.
Watch out Confident delivery is a strong social signal, so this audit runs directly against your instincts about who sounds credible.
In the wild
Asked directly whether consciousness is an emergent property of assembled cells or something more fundamental, Eagleman defines panpsychism carefully for the audience and then declines to pick. He points out that the only data we have — that strokes, tumours, injury and drugs all change consciousness — establishes only that the physical integrity of the system is necessary, and is consistent with either view.
→ A clean demonstration of holding a headline question open while still being precise about exactly what the evidence does establish.
Around the time Sapiens came out, Eagleman walked into a bookstore and saw the front table arranged as a confrontation: one pile by religious fundamentalists, one by neo-atheists. He rejected the framing rather than the piles, arguing that the useful move is shining a flashlight around the possibility space and making up more stories rather than picking a side.
→ The encounter crystallised possibilityism, which Eagleman says caught on and is still moving around the planet.
Common mistakes
Sliding from uncertainty into relativism
Tim names the trap directly: refusing certainty is not a claim that we can't know anything, which he calls a learned hopelessness that is not very helpful. Possibilityism still ranks by weight of evidence — Eagleman is happy to say the biblical stories are wrong in a thousand ways. Dropping the ranking discards the scientific half of the temperament.
Treating the negation of a wrong answer as proven
Eagleman's sharpest example is that having enough data to reject biblical accounts gives you nowhere near enough to assert there is nothing interesting in the cosmos besides us. Debunking is not the same as establishing the opposite, and the neo-atheist pile on that bookstore table made exactly this error.
Mistaking confident delivery for competence
The strongest performers Tim has met say 'I don't know' a lot, and a reference check that turned up almost no low-conviction statements made him nervous rather than impressed. Hiring, funding, or believing on the basis of conviction density selects for people who have stopped updating.
Is it for you?
Best for
Anyone forming views on genuinely unresolved questions — scientific, political, or personal — and anyone assessing how much to trust a confident expert.
Not ideal for
Situations that demand an immediate irreversible decision, or well-settled empirical questions where the weight of evidence is already overwhelming.
From the transcript
“years ago I proposed this new movement called possibilityism, which really caught on and actually is still moving around the planet well.”
“the idea with possibilityism is avoiding committing to something with certainty if you don't need to.”
“there's nothing in science that isn't vulnerable to getting knocked off its pedestal.”
“uncertainty is an uncomfortable position but certainty is an absurd one.”
From the episode
#674: Neuroscientist David Eagleman — Exploring Consciousness, Sensory Augmentation, The Lazy Susan Method of Extraordinary Productivity, Dreaming, Improving Hearing with a Wristband, Synesthesia, Stretching Time with Novelty, Lessons from Titans of Science, and Much More