Hypotheses, Cairns, and Decisions
The three working objects of the H-BMC, and how raw information becomes each of them.
Why This Matters
Most business plans fail quietly, at the level of the sentence. A claim written vaguely cannot be tested; a claim never tested is an assumption wearing a suit; and a choice presented as a fact cannot be revisited when the evidence moves. The H-BMC's discipline is that every entry on the canvas is one of three things, and says which: a hypothesis, a Cairn, or a decision.
Assumptions are not hypotheses. Assumptions are accepted without scrutiny. Hypotheses are formed with rigor, stated precisely, and designed to be challenged. The whole method is the practice of converting the first into the second.
What Makes a Hypothesis Well-Formed
A well-formed hypothesis names a specific stakeholder, makes one claim, and states the observable that would show it wrong. The standard shape:
We believe that [stakeholder] experiences [problem or behavior] because [cause or constraint], resulting in [impact or outcome].
Four tests, applied to every claim. Precise: could two people independently design the same measurement from this statement? Testable: could a skeptic design a way to disprove it? Discrete: if it fails, will you know exactly which assumption was invalid? Actionable: would the result change what you do next?
Weak: "We believe ICU staffing is a problem."
Strong: "We believe that ICU charge nurses cannot reliably anticipate staffing shortfalls more than four hours ahead because shift census data and acuity scoring are not integrated in real time, resulting in reactive staffing decisions that increase overtime costs and compromise care quality."
The "We believe that" framing is permanent. Evidence can make a belief well supported; it never converts a belief into a fact, and a supported hypothesis is still not a validated one until it has been tested against a threshold.
Stacking Hypotheses into Cairns
A cairn is a stack of stones that marks a route across ground where no path is visible. Each stone is placed deliberately; the stack marks ground you can trust. In the H-BMC, each hypothesis is a stone, and related, well-supported hypotheses stack into a Cairn: one consolidated, evidence-backed statement solid enough to build on.
The most important Cairn on the canvas is the unmet need. Its stones are the hypotheses discovery produces about four things: the job stakeholders are trying to accomplish, the outcomes by which they judge it done well, the alternatives they use today and how those fall short, and the gaps that matter most. When those components are each supported by evidence, they assemble into a formulated need:
"A way for bedside clinicians, without requiring specialized expertise, to establish reliable peripheral IV access in difficult-stick patients rapidly, with few attempts and low pain."
Two rules keep Cairns honest. A canvas rests on one or two need Cairns, not ten: if a third keeps emerging, you may be looking at two different businesses. And a Cairn is only as strong as its weakest stone: strong evidence about the gap cannot compensate for never having assessed the current alternatives.
Recording Decisions
Not everything on a canvas can be discovered. Price, channel, partners, and make-versus-buy are choices, and the H-BMC treats them as first-class objects rather than disguising them as findings. A well-recorded decision has four parts:
The options considered — including the ones you rejected, and why.
The choice and its rationale — citing the evidence that informed it.
What it commits you to believing — every choice implies claims: choosing a $380 per-procedure price commits you to believing buyers will pay it. Those implied claims become hypotheses and get tested like any others.
Its standing — a decision is proposed, made, supported by subsequent evidence, or contradicted by it. When the evidence behind a choice moves, the choice gets revisited, not defended.
Evidence should always prevail as honest feedback: it constrains and informs every decision, and the record shows where a team chose against it. But the team, not the evidence, owns the choice.
Interdependence
The canvas holds Cairns and Decisions; evidence, hypotheses, and implied claims live outside it, feeding and testing what is inside. And when a stone breaks, the break propagates: an invalidated hypothesis weakens its Cairn, and a weakened Cairn reopens every Decision that stood on it.
Hypotheses, Cairns, and Decisions form one system. Evidence raises hypotheses; hypotheses stack into Cairns; Cairns inform decisions; decisions imply new hypotheses; and testing those loops back into the evidence base. A change anywhere propagates: an invalidated stone weakens its Cairn, a weakened Cairn reopens the decisions that stood on it. That is not fragility, it is the design: the model updates when reality disagrees with it.