The CFO has just presented a multimillion-dollar acquisition. The numbers look good, the strategic logic seems sound, and the CEO is clearly enthusiastic. The most senior director asks for a couple of clarifications and then nods approvingly. A few minutes later, the rest of the board votes in favor. An efficient meeting. A terrible decision.
This scene illustrates a primitive instinct that sabotages board effectiveness: our brain is programmed to conserve cognitive energy. In the language of Nobel laureate Daniel Kahneman, we live in “System 1” — fast, intuitive, automatic thinking — when critical decisions require “System 2” — slow, analytical, energetically costly thinking.
The mental economy of the board
Thinking deeply consumes resources. The brain, representing only 2% of body weight, consumes 20% of our energy. Evolutionarily, this was a problem: spending mental energy on complex analysis meant having less energy to flee predators or hunt for food. The solution: developing mental shortcuts that let us decide quickly with minimal effort.
These shortcuts — heuristics — worked well on the savanna. In the boardroom, they are dangerous. When the first respected director backs a proposal, our primitive brain thinks: “Problem solved. I can save energy and join the consensus.” To question it would require activating System 2: analyzing assumptions, considering alternative scenarios, building counterarguments. It is exhausting.
Consensus as a cognitive refuge
This bias can be culturally amplified. Dissenting does not only cost mental energy — it costs social capital. It means positioning yourself against the group, defending a minority stance, sustaining tension while others are trying to close. It is easier to think: “If three experienced directors agree, they are probably right.”
The problem is that everyone is applying the same energy-saving logic. No one is really analyzing — everyone is assuming someone else did. It is the corporate version of the bystander effect: in an emergency, each person assumes someone else will call the ambulance, and no one calls.
The invisible cost of cognitive laziness
A McKinsey study on M&A decisions found that 70% of acquisitions destroy value, and the main cause is not a lack of information but “superficial analysis of critical assumptions.” Boards receive polished presentations that lay out the best-case scenario, but few take on the mental work of building alternative cases.
Why? Because building the opposing case is hard work. It requires suspending intuition, questioning the obvious, imagining improbable but possible scenarios. System 2 must be activated, and our brain resists that activation the way we would resist a gym session after an exhausting day.
Forcing slow thinking
Effective boards do not have smarter members — they have processes that force System 2. Some proven practices: formally assigning one director the role of “devil’s advocate,” tasked with building the opposing case; requiring that every proposal explicitly include its critical assumptions and what evidence would refute them; implementing 48-hour “cooling-off periods” before major decisions to allow for individual reflection.
In family businesses, where personal trust can substitute for rigorous analysis, these mechanisms are even more critical. The question is not whether they trust the CEO — it is whether their assumptions are correct.
For reflection in your boardroom: How many important decisions did you make in the last six months after less than an hour of discussion? Do you have formal mechanisms that force deep analysis? When was the last time you actively built the case against an attractive proposal?
Efficiency can be the enemy of effectiveness.
P.S. If everyone agrees quickly, no one is probably thinking hard enough.