# McNamara Fallacy ## The Idea in Brief When you measure only what's easy to measure, you start ignoring what isn't. Then you assume what isn't measured isn't important. Finally, you assume it doesn't exist. This is how organisations go blind while staring at dashboards. Named after Robert McNamara, who measured success in Vietnam by body count—and lost the war while "winning" by the numbers. --- ## The Four Steps Sociologist Daniel Yankelovich described the progression: 1. **Measure whatever can be easily measured.** Start with available data. Reasonable enough. 2. **Disregard that which cannot be measured easily.** Harder-to-quantify factors get less attention. Still seems practical. 3. **Presume that which cannot be measured easily is not important.** The unmeasured becomes the unimportant. A subtle but fatal shift. 4. **Presume that which cannot be measured easily does not exist.** Reality narrows to what fits in the spreadsheet. You're now blind. --- ## The Pattern McNamara brought quantitative management from Ford to the Pentagon. Body counts became the key metric for progress in Vietnam. The numbers looked good. The war was lost. The same pattern appears everywhere: **Education.** Schools optimise for test scores. Teaching quality, curiosity, love of learning—unmeasured, then unimportant, then invisible. Teaching to the test replaces teaching to understand. **Business.** KPIs trend upward while the business deteriorates. Customer satisfaction scores rise while loyalty erodes. Engagement metrics improve while culture rots. **Healthcare.** Wait times shrink while care quality declines. Throughput increases while outcomes worsen. --- ## Why It Happens Quantification feels rigorous. Numbers seem objective. "You can't manage what you can't measure" becomes an excuse to ignore what you can't easily count. But the most important things are often the hardest to measure: trust, morale, culture, judgment, relationships, meaning. Reduce these to proxies and you optimise the proxy while the underlying reality decays. --- ## The Antidote **Acknowledge what matters but can't be measured.** Name it. Discuss it. Make qualitative judgment legitimate. **Treat metrics as indicators, not reality.** The map is not the territory. Numbers point at something—they don't capture it. **Watch for the progression.** When you notice step 2 (disregarding the unmeasured), stop. You're one step from blindness. **Combine quantitative and qualitative.** Use numbers *and* judgment. Walk the floor. Talk to people. Look at what's actually happening, not just the dashboard. --- ## Sources - Daniel Yankelovich, *Corporate Priorities: A Continuing Study of the New Demands on Business* (1972) - Robert McNamara's application of quantitative methods at Ford and the Pentagon --- ## See Also - [[Goodhart's Law]] — When a measure becomes a target, it ceases to be a good measure - [[POSIWID]] — The purpose of a system is what it does, not what it claims - [[Dancing with Systems]] — Pay attention to what is important, not just what is quantifiable