McNamara Fallacy
Updated 2026-08-22
INTRODUCTION
English translation pending.
CORE DEFINITION
The McNamara fallacy is the error of deciding on the basis of the quantifiable alone while neglecting factors that are important but immeasurable. Its core idea traces to Robert McNamara's conduct of the Vietnam War, where measurable indicators drove decisions and led to failure, and it warns that what is measurable is not equivalent to what is important.
SCAFFOLDING EFFECT
Reduce cognitive load
- List the goals first: write the real objectives before looking at what the numbers can express. - Separate the proxy: check whether the indicator is standing in for a goal it cannot actually represent. - Name the unmeasured: state explicitly which important factors the current metrics cannot capture.
Anchor fast decisions
Measurement is not neutral: it promotes whatever it counts and demotes whatever it cannot. When a single proxy such as enemy body count is used to stand for progress, effort flows into raising the proxy because it is legible, while the unmeasured factors, such as political legitimacy, decay unseen. The failure then arrives as a surprise because the dashboard was healthy all the way down.
MINIMUM ACTION
In progress 0/1Practice this model in one real situation:
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Source support: Explicit
- zh.wikipedia.orghttps://zh.wikipedia.org/wiki/%E7%B3%BB%E7%BB%9F%E7%9A%84%E6%99%BA%E6%85%A7verified
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