There is no sense in being precise when you don't know what you're talking about
Not Deming — a paraphrase of von Neumann & MorgensternJohn von Neumann and Oskar Morgensternvon Neumann 1903–1957 · Morgenstern 1902–1977 · co-authors of Theory of Games and Economic Behavior (1944)
The snappy line is an undocumented compression. What von Neumann and Morgenstern actually wrote, on page 4 of Theory of Games and Economic Behavior (1944), is “There is no point in using exact methods where there is no clarity in the concepts and issues to which they are to be applied.” W. Edwards Deming did engage with that passage — he reviewed the book in June 1945 and restated the idea — but in different words, and Quote Investigator ↗ has never found a source for the crisp version, which first appears in print credited to von Neumann in 1987.
“There is no sense in being precise when you don't know what you're talking about” Not W. Edwards Deming — the crisp one-liner is an undocumented paraphrase. The documented sentence is John von Neumann and Oskar Morgenstern's: 'There is no point in using exact methods where there is no clarity in the concepts and issues to which they are to be applied.' — Theory of Games and Economic Behavior (Princeton University Press, 1944), p. 4. Via Quotle.info
⚠ The slide-ready mistake: crediting this to W. Edwards Deming. Use the credit shown above instead.
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In context
Evoking the world of John von Neumann — Hungarian-American mathematician and co-founder of game theory. Theme: "There is no sense in being precise when you don't know what you're talking about". Atmospheric and restrained, cinematic directional light, a muted period-appropriate palette, fine grain and texture. Compose with generous empty space for the quote and a small credit line. No lettering in the image itself.
Minimalist
Minimalist editorial slide for the quote "There is no sense in being precise when you don't know what you're talking about". Clean background, a single muted accent color, generous negative space, subtle paper or linen texture, no literal illustration — let the words carry it. Reserve clear space for a serif quote and a small credit line. No lettering in the image itself.
Provenance
Where the real sentence lives
Work
Theory of Games and Economic Behavior
Authors
John von Neumann and Oskar Morgenstern
First published
1944, Princeton University Press — the sentence is on page 4, Chapter 1, §1.2.4
Popular wording
Undocumented paraphrase; earliest instance documented by Quote Investigator is 1987
The lack of real success is largely due to a combination of unfavorable circumstances, some of which can be removed gradually. To begin with, the economic problems were not formulated clearly and are often stated in such vague terms as to make mathematical treatment a priori appear hopeless because it is quite uncertain what the problems really are. There is no point in using exact methods where there is no clarity in the concepts and issues to which they are to be applied. Consequently the initial task is to clarify the knowledge of the matter by further careful descriptive work.
Chapter 1, page 4
Chapter 1, ‘Formulation of the Economic Problem’, page 4. The third sentence here is the one the popular one-liner compresses — and the fourth is the part the compression throws away.
1908 — W. R. Boyce Gibson and Augusta Klein publish The Problem of Logic, which already contains the argument in miniature: “there is no point in being precise about the edges if there is uncertainty about the centre” — page 18 ↗.
1944 — von Neumann and Morgenstern publish Theory of Games and Economic Behavior; on page 4 they write that there is no point in using exact methods where there is no clarity in the concepts and issues to which they are to be applied — page 4 of a later Princeton printing ↗, whose pagination is unchanged.
June 1945 — W. Edwards Deming reviews the book in the Journal of the American Statistical Association (vol. 40, no. 230, from page 263) and restates the idea in his own words — catalogue record ↗.
1987 onward — the crisp one-liner appears in print credited to von Neumann with no citation, and is reprinted through 1995, 1999 and 2016; Quote Investigator ↗ has never seen a supporting source for it.
The excerpt shown is from Theory of Games and Economic Behavior, first published in 1944 by Princeton University Press. Publication after the rolling public-domain cut-off is not on its own decisive: a US work published between 1929 and 1963 stays in copyright only if its registration was renewed in the twenty-eighth year. This one was — Princeton’s own copyright page records the 1944 copyright as renewed in 1972 — and the press has kept the book in print continuously, through the 1947 second edition, the 1953 third edition and the 2004 sixtieth-anniversary edition. The text therefore remains in copyright. The popular one-line paraphrase has no documented author or first publication, so no separate rights claim can be made for it; it is quoted here only as the object of the fact-check.
Rights status is our research, not legal advice — and copyright varies by country and edition. For commercial or published use, confirm with the rightsholder. See terms.
Fact-check
Four names, one orphan sentence
This is a paraphrase in search of an author. Quote Investigator had to weigh four candidates — von Neumann, Morgenstern, Deming and Michael A. Jackson — before concluding that the snappy wording belongs to none of them.
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the popular short wordingW. Edwards Deming Commonly credited
Deming is one of the names Quote Investigator tested ↗, and there is a real reason for it: reviewing Theory of Games and Economic Behavior for the Journal of the American Statistical Association in June 1945, he singled out this exact passage and restated it. But what QI transcribes from that review is “it is often not certain just what the problems are, and there is no point in using exact methods under such circumstances” — the idea, not the epigram.
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the popular short wordingJohn von Neumann, on his own Unsourced since 1987
The earliest instance QI documents ↗ is a June 1987 technical report by Julio Cesar S. P. Leite, which pins on von Neumann “There’s no sense in being precise about something when you don’t even know what you are talking about” with no citation attached. A 1988 master’s thesis repeated it, footnoting Leite. QI has never seen a substantive supporting citation for the wording.
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how the line hardened into a quotation‘Von Neumann’s Axiom’ Citation-free reprints
Michael A. Jackson’s 1995 software-requirements lexicon printed both versions side by side, presenting the short one as something von Neumann “said more simply” in conversation; Arthur Bloch’s 1999 Murphy’s Law 2000 then ran it under the heading ‘Von Neumann’s Axiom’. Neither offered a source, per QI ↗.
✓The documented sentence is von Neumann and Morgenstern’s: “There is no point in using exact methods where there is no clarity in the concepts and issues to which they are to be applied” — Theory of Games and Economic Behavior (Princeton University Press, 1944), page 4 ↗.
Context
Why this one keeps landing on a famous name
The sentence people actually quote is a very good one-liner, and that is precisely the tell: it is too clean to be the original. What von Neumann and Morgenstern wrote on page 4 of Theory of Games and Economic Behavior is longer and more careful — a warning, aimed squarely at economists, that mathematics cannot rescue a question nobody has yet managed to state clearly. Their fix is unglamorous: “the initial task is to clarify the knowledge of the matter by further careful descriptive work.”
Deming’s name became attached because he was genuinely in the room. Reviewing the book for the Journal of the American Statistical Association in June 1945, he picked out that very passage and put it in his own words — but his words were not the famous line either. Somewhere between the 1945 review and the software-requirements literature of the late 1980s, the thought shed its clauses and acquired a punchline, and the punchline started travelling under whichever byline was closest to hand.
There is a source for the careful version. There has never been one for the crisp version.
An older cousin of the same thought
Quote Investigator points to a near-ancestor from 1908: in The Problem of Logic, W. R. Boyce Gibson and Augusta Klein wrote that “there is no point in being precise about the edges if there is uncertainty about the centre” — page 18 of the scanned first printing ↗. They were discussing when a word needs a formal definition, not when economics needs equations, but the shape of the argument is identical.
That is a useful reminder about how lines like this form. The observation itself is old and widely felt; what moves around over the decades is the byline, and it tends to drift toward whichever famous name sits nearest the subject — von Neumann for mathematics, Deming for measurement.
Explore
Filed under
More provenance-checked quotes on the same theme, each with its reuse status.
1903–1957 · Hungarian-American mathematician and co-founder of game theory
Von Neumann was the twentieth century’s most alarming generalist — a Budapest-born prodigy who did foundational work in set theory, quantum mechanics, computer architecture and weapons physics, often in the same decade. With the German-born, Vienna-trained economist Oskar Morgenstern he wrote Theory of Games and Economic Behavior (Princeton University Press, 1944), the book that created game theory as a field. The sentence quoted here comes from its opening chapter, where the two authors explain why economics had not yet earned the mathematics it kept reaching for — not from any recorded conversation.
For writers & researchers
Cite this
Primary source of the documented sentence
John von Neumann and Oskar Morgenstern, Theory of Games and Economic Behavior (Princeton, NJ: Princeton University Press, 1944), 4 — “There is no point in using exact methods where there is no clarity in the concepts and issues to which they are to be applied.” The popular short wording is an undocumented paraphrase; the earliest instance documented by Quote Investigator is a June 1987 technical report by Julio Cesar S. P. Leite, which credits von Neumann without a citation.
This verification page
Quotle.info. “Who really said ‘There is no sense in being precise when you don't know what you're talking about’?” Last verified 7 Aug 2026. https://quotle.info/who-said/there-is-no-sense-in-being-precise-when-you-dont-know-what/