What needs to be finished first
The initiative, idea, or decision is described in one sentence and its wording is stable.
What needs to be ready before start
Whiteboard or Miro board with a two-axis grid (importance, uncertainty); sticky notes; pens; timer; prepared list of typical assumption categories (users, market, technology, business model, organization).
One facilitator who separates assumptions sharply and leads the rating; two to eight participants with different perspectives; one scribe for the learning plan.
Initiative in one sentence; existing arguments and rationales; known data or research; time horizon and budget for assumption tests.
45-90 min
Put the initiative at the top of the board. Prepare the two-axis grid (X: uncertainty, Y: importance). Make the assumption categories visible. Rule: an assumption is anything we believe without knowing.
The one question this method answers
Which implicit assumptions hold up the initiative, and which of them are so important and uncertain that we need to test them before implementation?
Marker: Phase
| Step | Duration | Action | Hint |
|---|---|---|---|
1Phase 1: Clarify the initiative | 5-10 min | Read the initiative or decision aloud and clear up misunderstandings. Agree on one sentence that will not change for the rest of the workshop. | If the initiative still changes during the workshop, the set of assumptions changes with it. Fix it first. |
2Phase 2: Collect assumptions | 20-30 min | For each category (users, market, technology, business model, organization), do 5 min of solo writing, then place the notes on the board. Aim for at least three assumptions per category. | Assumptions often start with 'of course', 'naturally', or 'everyone knows'. Saying those phrases out loud helps reveal them. |
3Phase 3: Rate importance and uncertainty | 15-20 min | For each assumption, make two ratings: how important if wrong (1-5)? How uncertain (1-5)? Place the assumptions in the grid. Mark the top quadrant (high x high). | Uncertain is not the same as unknown. If we believe it is true but do not have evidence, it is uncertain. Gut feeling is not evidence. |
4Phase 4: Choose critical assumptions | 10-15 min | Select the top 3 assumptions from the 'important and uncertain' quadrant. For each one, ask: what would we do if it were false? | If the answer is 'then the initiative fails', testing before implementation is mandatory. If the answer is 'then we adapt', testing is useful but not mandatory. |
5Phase 5: Learning plan | 10-15 min | Choose one test per critical assumption: interview, smoke test, data analysis, spike, expert review. Note owner, date, and success criterion. | Tests must be cheaper than being wrong about the assumption. Anyone proposing a 6-week pilot for an assumption that could be tested in a 30-minute interview is optimizing badly. |
What comes out at the end
Importance-uncertainty grid as an image plus structured Markdown with the initiative, full assumption list per category, ratings, top 3 critical assumptions, and a learning plan with owner and date per test.
One entry per initiative with date. After each assumption test, update the assumption status: confirmed, disproved, or modified. Keep old assumptions and set a status instead of deleting them.
Compact working template for Assumption Surfacing with context, input, output artifacts, and next step.
Makes implicit assumptions behind ideas, decisions, or strategies visible.
When and for what do we use this method?
Which data, observations, decisions, or materials are available?
Short notes along the runsheet.
Owner, date, and success signal.
Concrete filled scenario, fictional example
Concrete filled scenario, fictional example
Initiative: We are building a 5-day onboarding flow for solo tax advisors like Sabine to increase activation from 22% to 38%.
Assumption excerpt:
Critical (top 3, quadrant 4-5 x 4-5):
Recognize symptoms and steer against them
The list contains statements like 'users want X' even though nobody has spoken to users.
Check every assumption: is there evidence that supports it? If not, it remains an assumption. If yes, it becomes a fact with a source.
There are 15 assumptions on the top quadrant and the learning plan becomes unrealistic.
Limit the method to at most 5 critical assumptions. Repeat the method if there are more, instead of weakening the filter.
Phase 3 takes 45 min because the group debates every assumption one by one.
Use dot voting or star distribution in parallel, not sequentially. Discuss only the assumptions that remain disputed.
Tests are named, but nobody knows what counts as passed.
Define a concrete success criterion for each test ('at least 5 of 8 report X'). Otherwise the test becomes gut-feel confirmation.
An assumption workshop is scheduled for every small initiative and energy drops.
Use the method only for substantial initiatives. For routine decisions, a 10-minute checklist per assumption category is enough.
Done signals checkable in under a minute
Go to the profile for purpose, similar methods, and sources or continue to the next method in the catalog.