How Leadership Assumptions Create Poor Business Decisions

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Leadership Judgement Series – Part One

Leadership Judgement: From Better Thinking to Better Business Decisions

Recently, The A to Z of Leadership Judgement introduced twenty-six principles that influence how leaders make decisions under uncertainty. This article is the first in a series exploring many of those principles in greater depth. Each article will focus on a real business problem faced by founders, owners and leadership teams—not as abstract leadership theory, but as practical disciplines that improve commercial decision-making.

Leadership judgement is not measured by the quality of decisions made when everything is obvious, but it is measured by the quality of decisions made when reality is changing faster than certainty.

Most Poor Business Decisions Begin Long Before the Decision Itself

Most expensive business decisions are not made because leadership teams lack intelligence, experience or commitment. In many cases, the opposite is true. Experienced leaders make logical decisions using the information available to them at the time.

Yet businesses still invest in declining markets.

Organisations continue allocating capital to traditional product lines because they have always generated strong returns, even as customer demand steadily shifts towards subscription models, digital services or new technologies.

They continue funding products that no longer reflect customer priorities.

Leadership teams spend years refining features customers once valued while overlooking the buying criteria that now influence purchasing decisions—such as implementation, integration, sustainability or commercial flexibility.

They recruit capabilities that made sense three years ago rather than those required for the next three.

Businesses continue hiring against yesterday’s growth strategy—expanding sales teams, technical functions or operational capacity—while the market increasingly demands different skills, new channels or changing customer expectations.

They pursue acquisitions built on market assumptions that have quietly changed.

Organisations acquire businesses that appear strategically complementary on paper, only to discover that customer behaviour, technology or competitive dynamics have already shifted, reducing much of the anticipated value before integration is even complete.

None of these decisions appear irrational when viewed in isolation. The problem often lies much earlier.

Every strategic decision is built upon leadership assumptions about customers, markets, competitors, employees and the future.

When those assumptions become outdated, even excellent leadership teams can make entirely rational decisions that produce poor commercial outcomes.

By the time declining margins, slowing growth or weakening customer relationships reveal the problem, organisations are often living with the financial consequences of assumptions that stopped reflecting reality months—or even years—earlier.

Leadership judgement begins long before a decision reaches the boardroom.

It begins by understanding the assumptions on which that decision is built.

Leadership Assumptions Are Necessary. Untested Assumptions Are Dangerous.

Every organisation depends upon assumptions. Without them, decisions would never be made.

Every business plan assumes future demand.
Every investment assumes future value.
Every recruitment decision assumes future capability.
Every product roadmap assumes future customer needs.

The objective is not to eliminate assumptions; that would be impossible.

The objective is to ensure they remain visible, open to challenge and regularly tested against reality. The greatest commercial risks rarely come from new assumptions.

They come from old assumptions that nobody thinks to question because they have quietly become “the way we think around here.”

Why Success Creates New Blind Spots

One of the greatest paradoxes of leadership is that success increases the likelihood of future assumptions.

Not because successful leaders become complacent, but because they become experienced. Experience develops pattern recognition, which allows leaders to simplify complexity, recognise opportunities and make decisions quickly.

It is one of leadership’s greatest strengths. However, the difficulty begins when yesterday’s successful patterns quietly become tomorrow’s expectations.

Expectation becomes assumption and assumption shapes strategy. Strategy drives investment and investment reinforces belief.

Over time, organisations begin making decisions based on interpretations of reality rather than reality itself. This is not a failure of intelligence, but often the unintended consequence of previous success.

The judgement that built the business gradually becomes the filter through which new evidence is interpreted.

That is why successful organisations must work harder—not less—to challenge their own thinking.

When Assumptions Stop Matching Reality

The difficulty is that markets, customers, technology and competitors can change far more quickly than the assumptions leadership teams have built up over time.

A business may continue believing customers choose it primarily because of product capability, even when implementation certainty has become the more important differentiator. A leadership team may keep investing heavily in a market segment because it generated exceptional returns five years ago, despite demand gradually moving elsewhere. Strong retention can continue to be interpreted as customer loyalty when, in reality, switching supplier has simply become more difficult than staying.

None of these decisions is inherently irrational. They can be entirely sensible decisions based on experience, historical evidence and assumptions that were once correct.

The problem emerges when those assumptions are no longer tested against current commercial reality.

That changes the leadership question. Rather than simply asking:

“Are we making good decisions?”

it is often more useful to ask:

“Are our decisions still based on an accurate understanding of today’s reality?”

That distinction matters because the quality of a decision depends heavily on the assumptions beneath it. Challenging those assumptions early can expose a growing gap between what the organisation believes and what is actually happening, long before declining margins, slowing growth or weakening customer relationships make the problem obvious.

A Practical Discipline for improved Leadership Assumptions

One practical way to improve leadership judgement is to make assumptions an explicit part of major strategic discussions, rather than allowing them to sit unnoticed beneath the decision.

Before approving a significant investment, entering a new market or committing substantial organisational resources, it is worth testing the thinking with five questions.

1. What assumptions are we making?
Bring them into the open. Assumptions that remain implicit are difficult to challenge because nobody is quite sure which part of the argument is being treated as fact and which part is being taken on trust.

2. Which assumptions are supported by current evidence?
The emphasis is on current. Historic success, instinct and internal consensus may all be useful inputs, but none of them proves that the same assumption still holds today.

3. Which assumptions have we not tested recently?
Long-standing assumptions often deserve the greatest scrutiny precisely because they feel so familiar. The longer something has been accepted as “how the market works” or “what our customers value”, the easier it is to stop checking whether it remains true.

4. What evidence would genuinely change our minds?
This is an important test of whether an assumption is still open to challenge. If no realistic evidence would cause the leadership team to reconsider it, the assumption may already have hardened into belief.

5. Who is most likely to see this differently?
Customers, employees, partners and independent advisers often encounter aspects of reality that are less visible from the leadership table. Their perspective does not automatically make the prevailing view wrong, but it can reveal where the organisation’s assumptions deserve another look.

The value in this discipline is not in proving assumptions wrong. It is in making them visible enough to test before they begin shaping strategy, investment and priorities on the organisation’s behalf.

Five Leadership Assumptions Worth Testing This Quarter

Leadership teams rarely suffer from too few assumptions. They suffer from assumptions that have quietly become accepted facts.