Steelman
McNamara fallacy
Also called quantitative fallacy, measuring what is easy to measure.
Treating what’s easy to measure as all that matters.
What it is
Making decisions based only on quantitative measures, and dismissing whatever can’t easily be measured as unimportant or nonexistent.
The pattern
Measure what can be counted. Ignore the rest. Conclude the measured quantity tells the whole story.
An example
A call center rewards agents for the shortest average call time, and customers start getting cut off before their problems are solved.
Call length was easy to count, but customer problems solved, the actual goal, wasn’t being measured.
Why it fails
Numbers capture only what they were designed to capture. When unmeasured factors matter, optimizing the metric can make the real goal worse.
When it’s not a fallacy
Most lists skip this part. Calling a fair point a fallacy is a mistake too.
It can be fair when
- Metrics are used together with judgment about what they leave out.
Try one
A question from the app. The wrong answers are its usual look-alikes.
Pub argument. Callum: “Games feel dead now. You score, then stand around for three minutes to find out if you’re allowed to celebrate.” Femi: “Our league’s report says VAR fixed 109 wrong calls last season, up from 61. That’s the scoreboard I go by. By that, the game’s never been in better shape.” Callum: “Kickoff’s in five. Grab the remote.” Femi: “Got it.”
What’s the flaw?
Femi counts what’s easy to count (corrected calls) and treats it as the whole health of the game. Callum’s point, how the game feels to play and watch, never shows up in that number, so it simply drops out.
A fair reply
“More right calls is real, but it doesn’t tell us whether the waiting has drained the fun out of it.”
Often confused with
- Cherry-picking
Cherry-picking hides unfavorable evidence. The McNamara fallacy ignores evidence that isn’t numerical.
Where the name comes from
Named for Robert McNamara, the US defense secretary who leaned on enemy body counts during the Vietnam War. Body counts were easy to tally; whether the war was being won wasn’t. “Quantitative fallacy” says the same thing: trusting quantities, what you can count, over everything else. “Measuring what is easy to measure” names the first step: count what’s countable, then forget the rest.
Named by Daniel Yankelovich in a 1971 speech, after Robert McNamara, US Secretary of Defense from 1961 to 1968, whose management of the Vietnam War leaned on metrics such as enemy body counts while harder-to-quantify factors were neglected.
Sources
- McNamara fallacy, Wikipedia
In the app
Practice spotting it on arguments that sound real.
Steelman has more examples of McNamara fallacy, how to answer it in a real conversation, and practice rounds that mix it with its look-alikes, so you learn the difference, not just the name. Coming soon to iPhone and Android.
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