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RAND Studies in Policy Analysis
[(Assumption-Based Planning: A Tool for Reducing Avoidable Surprises )] [Author: James A. Dewar] [Nov-2002]
Unwelcome surprises in the life of any organization can often be traced to the failure of an assumption that the organization's leadership didn't anticipate or had "forgotten." Assumption-based planning (ABP) is a tool for identifying as many as possible assumptions underlying the plans of an organization and bringing them explicitly into the planning process. This book presents a variety of techniques for rooting out those vulnerable, crucial assumptions. It also presents steps for monitoring the vulnerable assumptions of a plan by taking actions to control them where possible and preparing for potential failure where control is not possible.
Unknown Binding
First published May 27, 1997
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March 2, 2026
a signpost is only valuable if it buys you time
notes:
- Spreadsheets don't account for chaos. The confidence we feel might just be a story we tell ourselves to avoid staring into the unknown.
- What you actually built was a structure held up by invisible beams. And when plans fall apart, it’s rarely because the vision was flawed or the execution was careless. It’s because one of those invisible beams snapped. Those beams are called assumptions.
- You need to identify load-bearing assumptions: the ones whose failure would force you to completely rethink your plans.
- In Sylvia’s case, her loyalty makes her availability seem guaranteed. But if she’s suddenly unavailable – a family emergency, an unexpected illness – that implicit beam snaps. Because you didn’t know it was there, you have no backup. The plan collapses.
- Traditional planning often encourages you to focus on the decoration – the goals, the marketing, the rollout – while ignoring the structural integrity underneath. To build a strategy that survives contact with reality, you have to stop looking at what you plan to do and start looking for what you’re expecting to happen.
- 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.
- 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.
- 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.
- The next word to track is “must.” Planners use it to describe actions they see as non-negotiable – “We must cut headcount,” “The logistics system must handle increased volume.” These imperatives are the structural pillars of your response to the future. Where “will” shows what you believe about the world, “must” shows what you believe about your own capabilities and constraints. Strip a document down to its “wills” and “musts,” and you’re left with a skeleton map of your certainties.
- you need to examine the logic of the plan itself. Think of this as reverse-engineering the “therefore” in your strategy. Every action exists to solve a problem or seize an opportunity. You should be able to draw a line from each specific action to a specific belief about the future. If your plan includes a massive budget for a new factory, there’s an implicit “therefore” linking it to a belief that demand is going to rise.
- By forcing yourself to connect every “what we’re doing” to a “why we’re doing it,” you drag these silent justifications into the open.
- What looked like a clean path forward now resembles a minefield. You started with a handful of explicit risks – now you might be staring at dozens, even hundreds, of assumptions. This creates a new problem: paralysis. You can’t monitor or hedge against hundreds of variables. So, the next challenge becomes figuring out which of these assumptions are actually capable of destroying you – and which ones you can safely set aside.
other:
- 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.
- This is a trap. Calculating the precise likelihood of a unique future event is often just guessing with better math.
- Rip Van Winkle technique. It goes like this: you fall into a deep sleep today and wake up twenty years from now. You have no idea what has happened to your industry, your market, or your company. You’re allowed exactly ten yes-or-no questions to figure out if your organization survived and thrived. You can’t ask, “How is the economy?” You have to ask something like, “Did interest rates stay below five percent?”
- When you only have ten questions to determine your fate, you stop caring about minor details. You don’t ask about office supply costs or software updates. You ask about the fundamental drivers of your business.
- These are the few critical beams that, if broken, bring the whole structure down.
- By applying this filter, your unmanageable list of hundreds shrinks to a focused handful of critical threats.
on radar/time:
- Knowing a beam might crack is useful. Knowing when it’s starting to crack – that’s what lets you act in time.
- 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.
- Aimpoints measure success. Signposts detect failure.
- If your plan assumes you’ll hit that $50 million target, a signpost isn’t the failure to reach it in December – that’s just an autopsy. A true signpost would be missing a leading indicator in April – perhaps raising only $30 million when the model demanded $40 million. Detecting that gap early gives you months to adjust. Waiting for the final deadline gives you nothing but regret.
1. shaping
When you identify a vulnerable assumption, say, that customers will embrace your new technology, a shaping action is an offensive move designed to make that assumption come true. You don’t hope for demand – you launch an aggressive education campaign to create it. You’re acting now to shore up the beam and remove the risk entirely. Shaping feels like leadership. It assumes that with enough effort, you can bend the world to fit your plan.
2. hedging
is about insurance. It requires the humility to admit that a load-bearing beam might still snap despite your best efforts. If your plan assumes your car will get you to a meeting, a shaping action is getting a tune-up. A hedging action is putting a spare tire in the trunk. You don’t buy that spare because you want a flat, but because you respect the plausibility that one could occur.
- By refusing to hedge, you’re selling your safety, not making money.
notes:
- Spreadsheets don't account for chaos. The confidence we feel might just be a story we tell ourselves to avoid staring into the unknown.
- What you actually built was a structure held up by invisible beams. And when plans fall apart, it’s rarely because the vision was flawed or the execution was careless. It’s because one of those invisible beams snapped. Those beams are called assumptions.
- You need to identify load-bearing assumptions: the ones whose failure would force you to completely rethink your plans.
- In Sylvia’s case, her loyalty makes her availability seem guaranteed. But if she’s suddenly unavailable – a family emergency, an unexpected illness – that implicit beam snaps. Because you didn’t know it was there, you have no backup. The plan collapses.
- Traditional planning often encourages you to focus on the decoration – the goals, the marketing, the rollout – while ignoring the structural integrity underneath. To build a strategy that survives contact with reality, you have to stop looking at what you plan to do and start looking for what you’re expecting to happen.
- 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.
- 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.
- 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.
- The next word to track is “must.” Planners use it to describe actions they see as non-negotiable – “We must cut headcount,” “The logistics system must handle increased volume.” These imperatives are the structural pillars of your response to the future. Where “will” shows what you believe about the world, “must” shows what you believe about your own capabilities and constraints. Strip a document down to its “wills” and “musts,” and you’re left with a skeleton map of your certainties.
- you need to examine the logic of the plan itself. Think of this as reverse-engineering the “therefore” in your strategy. Every action exists to solve a problem or seize an opportunity. You should be able to draw a line from each specific action to a specific belief about the future. If your plan includes a massive budget for a new factory, there’s an implicit “therefore” linking it to a belief that demand is going to rise.
- By forcing yourself to connect every “what we’re doing” to a “why we’re doing it,” you drag these silent justifications into the open.
- What looked like a clean path forward now resembles a minefield. You started with a handful of explicit risks – now you might be staring at dozens, even hundreds, of assumptions. This creates a new problem: paralysis. You can’t monitor or hedge against hundreds of variables. So, the next challenge becomes figuring out which of these assumptions are actually capable of destroying you – and which ones you can safely set aside.
other:
- 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.
- This is a trap. Calculating the precise likelihood of a unique future event is often just guessing with better math.
- Rip Van Winkle technique. It goes like this: you fall into a deep sleep today and wake up twenty years from now. You have no idea what has happened to your industry, your market, or your company. You’re allowed exactly ten yes-or-no questions to figure out if your organization survived and thrived. You can’t ask, “How is the economy?” You have to ask something like, “Did interest rates stay below five percent?”
- When you only have ten questions to determine your fate, you stop caring about minor details. You don’t ask about office supply costs or software updates. You ask about the fundamental drivers of your business.
- These are the few critical beams that, if broken, bring the whole structure down.
- By applying this filter, your unmanageable list of hundreds shrinks to a focused handful of critical threats.
on radar/time:
- Knowing a beam might crack is useful. Knowing when it’s starting to crack – that’s what lets you act in time.
- 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.
- Aimpoints measure success. Signposts detect failure.
- If your plan assumes you’ll hit that $50 million target, a signpost isn’t the failure to reach it in December – that’s just an autopsy. A true signpost would be missing a leading indicator in April – perhaps raising only $30 million when the model demanded $40 million. Detecting that gap early gives you months to adjust. Waiting for the final deadline gives you nothing but regret.
1. shaping
When you identify a vulnerable assumption, say, that customers will embrace your new technology, a shaping action is an offensive move designed to make that assumption come true. You don’t hope for demand – you launch an aggressive education campaign to create it. You’re acting now to shore up the beam and remove the risk entirely. Shaping feels like leadership. It assumes that with enough effort, you can bend the world to fit your plan.
2. hedging
is about insurance. It requires the humility to admit that a load-bearing beam might still snap despite your best efforts. If your plan assumes your car will get you to a meeting, a shaping action is getting a tune-up. A hedging action is putting a spare tire in the trunk. You don’t buy that spare because you want a flat, but because you respect the plausibility that one could occur.
- By refusing to hedge, you’re selling your safety, not making money.
Read
March 2, 2026**HAPPY HOLI 2082**
In "Assumption-Based Planning: A Tool for Reducing Avoidable Surprises", James A. Dewar presents a method for strengthening strategies by uncovering the hidden assumptions that silently support them and preparing for the possibility that those assumptions may fail. The book challenges the common belief that careful planning and detailed execution are enough to guarantee success. Instead, it argues that plans most often break down not because of flawed goals or poor effort, but because they depend on unexamined beliefs about the future that may not hold true. By learning to identify, test, and manage these assumptions, planners can transform fragile strategies into resilient systems capable of adapting to uncertainty.
The discussion begins with a simple but powerful insight: every plan is built on a set of expectations about how the world will behave. These expectations may concern people, resources, markets, or timelines, and they often feel so obvious that they are treated as facts rather than guesses. Yet each one represents a gap between what is known and what must be true for the plan to succeed. When one of these expectations proves false, the structure built upon it can collapse. The most dangerous assumptions are those that remain implicit, because they are not recognized or monitored. Familiarity can make them feel like certainties, causing planners to overlook their vulnerability until it is too late to respond.
To uncover these hidden risks, Dewar suggests examining planning documents with a critical eye. The language used to describe the future often reveals underlying confidence levels. Statements framed as inevitabilities signal beliefs that may actually be uncertain. Similarly, declarations about what must be done reflect judgments about capabilities and constraints. By isolating these elements, planners can begin to map out the assumptions that support each action. Another useful approach is to trace the logic of each initiative back to the belief that justifies it. If a decision cannot be clearly linked to a specific expectation about the future, it likely rests on an unstated assumption that should be brought into the open.
Once these assumptions are visible, the next step is to determine which ones truly matter. It is neither practical nor necessary to guard against every possible uncertainty. Instead, planners should focus on those assumptions that are both essential to the plan and realistically capable of failing. Dewar emphasizes plausibility rather than probability, encouraging planners to consider whether a scenario could happen within the relevant timeframe rather than trying to calculate exact odds. A helpful thought experiment imagines looking back from the future and identifying the key factors that would determine success or failure. This exercise quickly highlights the small number of critical conditions that support the entire strategy.
After identifying these crucial assumptions, the focus shifts to monitoring them. Because the consequences of failure can be severe, it is important to detect changes as early as possible. Dewar introduces the idea of signposts, which are observable events or thresholds that indicate whether an assumption is holding or beginning to weaken. These indicators differ from final outcomes or goals; they are early signals that provide time to adjust course before the situation becomes irreversible. The value of a signpost depends on how much warning it provides. If the signal appears only when the damage has already occurred, it offers no practical benefit. Effective monitoring therefore requires identifying indicators that appear early enough to allow meaningful response.
However, not all risks can be monitored in time. Some events unfold too quickly or unpredictably to allow for early detection. In such cases, the planner must shift from observation to preparation. Dewar outlines two complementary approaches for strengthening plans against these threats. The first involves taking actions that influence the environment in ways that make key assumptions more likely to hold. This proactive approach seeks to shape outcomes by guiding behavior, building demand, or reinforcing conditions that support the plan. The second approach involves creating safeguards that reduce the impact of failure if it occurs. These protective measures act as a form of insurance, ensuring that the plan can continue or recover even if an important assumption proves false.
The balance between these two approaches depends on the degree of control available. When conditions can be influenced, shaping actions may reduce risk by aligning reality with expectations. When conditions lie beyond control, hedging actions provide security by preparing for alternative outcomes. Although hedging can appear inefficient or unnecessary, Dewar argues that it is a vital investment in resilience. A plan that eliminates all redundancy may appear efficient, but it becomes dangerously brittle when circumstances change. Incorporating safeguards ensures that a single unexpected event does not cause complete failure.
Throughout the book, Dewar emphasizes that the goal of this process is not to predict the future with perfect accuracy. Instead, it is to acknowledge uncertainty and build strategies that can withstand it. By identifying assumptions, assessing their vulnerability, monitoring their validity, and preparing for their potential failure, planners move from a mindset of optimism to one of preparedness. This approach transforms planning from a static exercise into a dynamic system that evolves alongside changing conditions.
The broader implication of this method is a shift in how planning itself is understood. Rather than focusing solely on desired outcomes, planners must also consider the conditions required for those outcomes to occur. This perspective encourages a more disciplined and reflective approach, one that recognizes the limits of knowledge while still enabling effective action. It replaces the illusion of certainty with a structured process for managing uncertainty.
In conclusion, "Assumption-Based Planning: A Tool for Reducing Avoidable Surprises" demonstrates that the greatest risks to any plan lie not in visible obstacles but in the unseen beliefs that support it. By learning to identify and test these assumptions, planners can anticipate potential disruptions and prepare for them in advance. The combination of early warning indicators, proactive shaping actions, and protective hedges creates strategies that are both flexible and durable. Through this approach, planning becomes less about predicting a single future and more about building systems capable of adapting to whatever future actually unfolds.
In "Assumption-Based Planning: A Tool for Reducing Avoidable Surprises", James A. Dewar presents a method for strengthening strategies by uncovering the hidden assumptions that silently support them and preparing for the possibility that those assumptions may fail. The book challenges the common belief that careful planning and detailed execution are enough to guarantee success. Instead, it argues that plans most often break down not because of flawed goals or poor effort, but because they depend on unexamined beliefs about the future that may not hold true. By learning to identify, test, and manage these assumptions, planners can transform fragile strategies into resilient systems capable of adapting to uncertainty.
The discussion begins with a simple but powerful insight: every plan is built on a set of expectations about how the world will behave. These expectations may concern people, resources, markets, or timelines, and they often feel so obvious that they are treated as facts rather than guesses. Yet each one represents a gap between what is known and what must be true for the plan to succeed. When one of these expectations proves false, the structure built upon it can collapse. The most dangerous assumptions are those that remain implicit, because they are not recognized or monitored. Familiarity can make them feel like certainties, causing planners to overlook their vulnerability until it is too late to respond.
To uncover these hidden risks, Dewar suggests examining planning documents with a critical eye. The language used to describe the future often reveals underlying confidence levels. Statements framed as inevitabilities signal beliefs that may actually be uncertain. Similarly, declarations about what must be done reflect judgments about capabilities and constraints. By isolating these elements, planners can begin to map out the assumptions that support each action. Another useful approach is to trace the logic of each initiative back to the belief that justifies it. If a decision cannot be clearly linked to a specific expectation about the future, it likely rests on an unstated assumption that should be brought into the open.
Once these assumptions are visible, the next step is to determine which ones truly matter. It is neither practical nor necessary to guard against every possible uncertainty. Instead, planners should focus on those assumptions that are both essential to the plan and realistically capable of failing. Dewar emphasizes plausibility rather than probability, encouraging planners to consider whether a scenario could happen within the relevant timeframe rather than trying to calculate exact odds. A helpful thought experiment imagines looking back from the future and identifying the key factors that would determine success or failure. This exercise quickly highlights the small number of critical conditions that support the entire strategy.
After identifying these crucial assumptions, the focus shifts to monitoring them. Because the consequences of failure can be severe, it is important to detect changes as early as possible. Dewar introduces the idea of signposts, which are observable events or thresholds that indicate whether an assumption is holding or beginning to weaken. These indicators differ from final outcomes or goals; they are early signals that provide time to adjust course before the situation becomes irreversible. The value of a signpost depends on how much warning it provides. If the signal appears only when the damage has already occurred, it offers no practical benefit. Effective monitoring therefore requires identifying indicators that appear early enough to allow meaningful response.
However, not all risks can be monitored in time. Some events unfold too quickly or unpredictably to allow for early detection. In such cases, the planner must shift from observation to preparation. Dewar outlines two complementary approaches for strengthening plans against these threats. The first involves taking actions that influence the environment in ways that make key assumptions more likely to hold. This proactive approach seeks to shape outcomes by guiding behavior, building demand, or reinforcing conditions that support the plan. The second approach involves creating safeguards that reduce the impact of failure if it occurs. These protective measures act as a form of insurance, ensuring that the plan can continue or recover even if an important assumption proves false.
The balance between these two approaches depends on the degree of control available. When conditions can be influenced, shaping actions may reduce risk by aligning reality with expectations. When conditions lie beyond control, hedging actions provide security by preparing for alternative outcomes. Although hedging can appear inefficient or unnecessary, Dewar argues that it is a vital investment in resilience. A plan that eliminates all redundancy may appear efficient, but it becomes dangerously brittle when circumstances change. Incorporating safeguards ensures that a single unexpected event does not cause complete failure.
Throughout the book, Dewar emphasizes that the goal of this process is not to predict the future with perfect accuracy. Instead, it is to acknowledge uncertainty and build strategies that can withstand it. By identifying assumptions, assessing their vulnerability, monitoring their validity, and preparing for their potential failure, planners move from a mindset of optimism to one of preparedness. This approach transforms planning from a static exercise into a dynamic system that evolves alongside changing conditions.
The broader implication of this method is a shift in how planning itself is understood. Rather than focusing solely on desired outcomes, planners must also consider the conditions required for those outcomes to occur. This perspective encourages a more disciplined and reflective approach, one that recognizes the limits of knowledge while still enabling effective action. It replaces the illusion of certainty with a structured process for managing uncertainty.
In conclusion, "Assumption-Based Planning: A Tool for Reducing Avoidable Surprises" demonstrates that the greatest risks to any plan lie not in visible obstacles but in the unseen beliefs that support it. By learning to identify and test these assumptions, planners can anticipate potential disruptions and prepare for them in advance. The combination of early warning indicators, proactive shaping actions, and protective hedges creates strategies that are both flexible and durable. Through this approach, planning becomes less about predicting a single future and more about building systems capable of adapting to whatever future actually unfolds.
February 7, 2018
Based upon a planning methodology developed at the Rand Corporation for the military, assumption-based planning is really what happens after a strategic plan is developed. Planners carefully review the plan to see if the assumptions make sense and are likely or unlikely to fail. Filled with jargon that they created when the author and his colleagues created this process, so part of learning about this process is just learning the jargon. Still, testing the assumptions on which your plan is based is a good idea. This just belabors the point.
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