McNamara fallacy

Short description: Erroneous reasoning based solely on numeric metrics

The McNamara fallacy (also known as the quantitative fallacy),[1] named for Robert McNamara, the US Secretary of Defense from 1961 to 1968, involves making a decision based solely on quantitative observations (or metrics) and ignoring all others. The reason given is often that these other observations cannot be proven.

> But when the McNamara discipline is applied too literally, the first step is to measure whatever can be easily measured. The second step is to disregard that which can't easily be measured or given a quantitative value. The third step is to presume that what can't be measured easily really isn't important. The fo[u]rth step is to say that what can't be easily measured really doesn't exist. This is suicide.

— Daniel Yankelovich, "Interpreting the New Life Styles", Sales Management (1971)[2]

The quote originally referred to McNamara's ideology during the two months that he was president of Ford Motor Company, but has since been interpreted to refer to his attitudes during the Vietnam War.

## Contents

* 1 Examples in warfare
* 1.1 Vietnam War
* 1.2 Global war on terror
* 2 In modern clinical trials
* 3 In competitive admissions processes
* 4 See also
* 5 References

## Examples in warfare

### Vietnam War

The McNamara fallacy is often considered in the context of the Vietnam War,[3] in which enemy body counts were taken to be a precise and objective measure of success. War was reduced to a mathematical model: By increasing estimated enemy deaths and minimizing one's own, victory was assured. Critics[who?] note that guerrilla warfare, widespread resistance, and inevitable inaccuracies in estimates of enemy casualties can thwart this formula. McNamara's interest in quantitative figures is seen in Project 100,000: by lowering admission standards to the military, enlistment was increased. Key to this decision was the idea that one soldier is, in the abstract, more or less equal to another, and that with the right training and superior equipment, he would factor positively in the mathematics of warfare.

US Air Force Brigadier General Edward Lansdale reportedly told McNamara,[4] who was trying to develop a list of metrics to allow him to scientifically follow the progress of the war, that he was not considering the feelings of the common rural Vietnamese people. McNamara wrote it down on his list in pencil, then erased it and told Lansdale that he could not measure it, so it must not be important.

### Global war on terror

Donald Rumsfeld, US Secretary of Defense under George W. Bush, sought to prosecute wars with better data, clear objectives, and achievable goals. Writes Jon Krakauer:

> ... the sense of urgency attached to the mission came from little more than a bureaucratic fixation on meeting arbitrary deadlines so missions could be checked off a list and tallied as 'accomplished'. This emphasis on quantification has always been a hallmark of the military, but it was carried to new heights of fatuity during Donald Rumsfeld's tenure at The Pentagon. Rumsfeld was obsessed with achieving positive 'metrics' that could be wielded to demonstrate progress in the Global War on Terror.

— Jon Krakauer, Where Men Win Glory.[5]

## In modern clinical trials

There has been increasing discussion of the McNamara fallacy in medical literature.[6][7] In particular, the McNamara fallacy is invoked to describe the inadequacy of only using progression-free survival (PFS) as a primary endpoint in clinical trials for agents treating metastatic solid tumors simply because PFS is an endpoint which is merely measurable, while failing to capture outcomes which are more meaningful, such as overall quality of life or overall survival.

## In competitive admissions processes

In competitive admissions processes—such as those used for graduate medical education[8]—evaluating candidates using only numerical metrics results in ignoring non-quantifiable factors and attributes which may ultimately be more relevant to the applicant's success in the position.

## See also

* Allegory of the cave
* Goodhart's law
* Metric fixation
* Newton's flaming laser sword
* Occam's razor
* Streetlight effect
* Surrogation
* Truth
* Verificationism
* Verisimilitude

## References

1. ↑ Fischer, D. H. (June 1970). Historians' fallacies: toward a logic of historical thought. Harper torchbooks (first ed.). New York: HarperCollins. p. 90. ISBN 978-0-06-131545-9. OCLC 185446787. https://archive.org/details/historiansfallac00fisc.
2. ↑ Yankelovich, Daniel (1971-11-15). "Interpreting the New Life Styles". Sales Management, the Marketing Magazine (Dartnell Corporation). https://archive.org/details/sim_sales-management_1971-11-15_107_11/page/26/mode/2up?view=theater. Retrieved 2023-03-11.
3. ↑ Baskin, Jonathan Salem. "According To U.S. Big Data, We Won The Vietnam War" (in en). https://www.forbes.com/sites/jonathansalembaskin/2014/07/25/according-to-big-data-we-won-the-vietnam-war/.
4. ↑ Phillips, Rufus (2008). Why Vietnam Matters. ISBN 978-1-682-47310-8.
5. ↑ Krakauer, Jon. 2009. Where Men Win Glory. NY: Bloomsbury, p. 246.
6. ↑ Basler, Michael H. (2009). "Utility of the McNamara fallacy". BMJ 339: b3141. doi:10.1136/bmj.b3141.
7. ↑ Booth, Christopher M.; Eisenhauer, Elizabeth A. (2012). "Progression-Free Survival: Meaningful or Simply Measurable?". Journal of Clinical Oncology 30 (10): 1030–1033. doi:10.1200/JCO.2011.38.7571. PMID 22370321.
8. ↑ Carmody, JB (2019). "On residency selection and the quantitative fallacy.". Journal of Graduate Medical Education 11 (4): 420–421. doi:10.4300/JGME-D-19-00453.1. PMID 31440336.

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Fallacies (list)

Formal|

| In propositional logic|

* Affirming a disjunct
* Affirming the consequent
* Denying the antecedent
* Argument from fallacy

|

In quantificational logic|

* Existential
* Illicit conversion
* Proof by example
* Quantifier shift

Syllogistic fallacy|

* Affirmative conclusion from a negative premise
* Exclusive premises
* Existential
* Necessity
* Four terms
* Illicit major
* Illicit minor
* Negative conclusion from affirmative premises
* Undistributed middle

* Masked man
* Mathematical fallacy

Informal|

| Equivocation|

* Equivocation
* False equivalence
* False attribution
* Quoting out of context
* Loki's Wager
* No true Scotsman
* Reification

|

Question-begging fallacies|

* Circular reasoning / Begging the question
* Loaded language
* Leading question
* Compound question / Loaded question / Complex question
* No true Scotsman

Correlative-based fallacies|

* False dilemma
* Perfect solution
* Denying the correlative
* Suppressed correlative

Illicit transference|

* Composition
* Division
* Ecological

Secundum quid
(ignoring qualifications)|

* Accident
* Converse accident

Faulty generalization|

* Anecdotal evidence
* Sampling bias
* Cherry picking
* McNamara
* Base rate / Conjunction
* Double counting
* False analogy
* Slothful induction
* Overwhelming exception

Vagueness / Ambiguity|

* Accent
* Syntactic ambiguity
* Continuum
* Sorites paradox
* False precision
* Moving the goalposts
* Slippery slope
* Quoting out of context

Questionable cause|

* Animistic
* Furtive
* Correlation implies causation
* Cum hoc
* Post hoc
* Gambler's
* Inverse
* Regression
* Single cause
* Slippery slope
* Texas sharpshooter

Fallacies of relevance|

| Appeals to emotion|

* Fear
* Flattery
* Novelty
* Pity
* Ridicule
* Think of the children
* In-group favoritism
* Invented here / Not invented here
* Island mentality
* Loyalty
* Parade of horribles
* Spite
* Stirring symbols
* Wisdom of repugnance

|

Genetic fallacies|

| Ad hominem|

* Abusive
* Association
* Reductio ad Hitlerum
* Godwin's law
* Reductio ad Stalinum
* Circumstantial
* Appeal to motive
* Bulverism
* Poisoning the well
* Tone
* Tu quoque
* Whataboutism

|

* Authority
* Accomplishment
* Ipse dixit
* Poverty / Wealth
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* Nature
* Tradition / Novelty
* Chronological snobbery

Appeals to consequences|

* Argumentum ad baculum
* Wishful thinking

* Ad nauseam
* Argument to moderation
* Argumentum ad populum
* Appeal to the stone / Proof by assertion
* Ignoratio elenchi
* Argument from silence
* Invincible ignorance
* Moralistic / Naturalistic
* Motte-and-bailey fallacy
* Rationalization
* Red herring
* Appeal to worse problems
* Two wrongs make a right
* Special pleading
* Straw man
* Cliché
* I'm entitled to my opinion

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