Assumption-Based Planning summary

To spot these hidden dangers, treat your strategic documents less like sacred texts and more like crime scenes. You’re looking for fingerprints – traces of the beliefs that shaped the plan but were never spelled out. And the best detective tool here is surprisingly low-tech: grammar. The language you use to describe the future betrays how certain you feel about it. That certainty is exactly where assumptions hide.

Start by hunting for the word “will.” When planners write strategy, they reach for “will” constantly – “Competition will be brutal,” “Technology will reshape the sector.” These sentences look like facts, but they’re actually bets. By scanning your documents for every “will,” you can pinpoint the moments where you stopped treating the future as a range of possibilities and locked onto a single path. Each one is a load-bearing assumption waiting to be tested.

Facing a sprawling list of hundreds of assumptions is paralyzing. It feels less like a strategic asset and more like an indictment of your entire project. If you try to build a defense against every single potential crack in the foundation, you will run out of time and money long before you launch. You have to triage. You need a ruthless filter to separate trivial concerns from structural killers. The goal now is to identify which of these many assumptions are both indispensable to your success and genuinely capable of breaking.

The first instinct most planners have is to ask, “What are the odds?” They look at a risk – like a competitor slashing prices – and try to assign a percentage probability to it. This is a trap. Calculating the precise likelihood of a unique future event is often just guessing with better math.

Building a radar system for your strategy starts with a simple realization: by the time a disaster actually hits, it’s too late to plan. You can’t buy fire insurance when the kitchen is already ablaze. 

To survive, you need to identify specific, observable events that act as early warnings – indicators that a load-bearing beam is beginning to buckle before the roof comes down. In Assumption-Based Planning, these indicators are called signposts. A signpost is an unambiguous event or threshold that signals a change in how valid an assumption really is. It’s the difference between a vague worry that “the market might turn” and a concrete alert that “sales have dropped for three consecutive weeks.”

Once you accept that some storms arrive without warning – that the foliage is too thick or the event too sudden for your radar to save you – the nature of your responsibility shifts. You can no longer be satisfied with watching the horizon. You must move from passive observer to active architect. You’ve identified the invisible beams holding up your strategy, stress-tested their vulnerability, and set up your early warning systems. Now comes the final phase: fortification.

There are two ways to fortify a plan. They represent opposite philosophical approaches to the future.