If Your Only Tool Is a Hammer Then Every Problem Looks Like a Nail

Mark Twain? Abraham Maslow? Abraham Kaplan? Silvan Tomkins? Kenneth Mark Colby? Lee Loevinger? Anonymous?

Dear Quote Investigator: The tools that we are able to apply to problems alter our perceptions of the challenges we face and the solutions that are appropriate. A popular adage illustrates this idea with a compelling analogy. Here are three versions:

1) To a man with a hammer, everything looks like a nail.
2) If your only tool is a hammer then every problem looks like a nail.
3) Give a young boy a hammer, and he will treat everything as a nail.

This saying is often attributed to Mark Twain, but I have been unable to find anything that fits in his writings. Do you know who should receive credit for this modern proverb?

Quote Investigator: Expert Ralph Keyes examined this saying in his reference work “The Quote Verifier”, and he noted that the linkage to Mark Twain was unsupported: 1

Credit for this familiar quotation has been given to everyone from Buddha to Bernard Baruch. Mark Twain is the most common recipient, based on no evidence whatsoever.

A thematic precursor involving a boy was published in a London periodical called “Once a Week” in 1868. The notion of a child wielding a hammer with overeager energy also occurred in later citations: 2

Give a boy a hammer and chisel; show him how to use them; at once he begins to hack the doorposts, to take off the corners of shutter and window frames, until you teach him a better use for them, and how to keep his activity within bounds.

In February 1962 a conference of the American Educational Research Association was held and Abraham Kaplan, a Professor of Philosophy at UCLA, gave a banquet speech. Several months later in June 1962 a report on the gathering was published in the “Journal of Medical Education”. The following excerpt about the speech included the earliest strong match for the adage known to QI. Boldface has been added: 3

The highlight of the 3-day meeting, however, was to be found in Kaplan’s comment on the choice of methods for research. He urged that scientists exercise good judgment in the selection of appropriate methods for their research. Because certain methods happen to be handy, or a given individual has been trained to use a specific method, is no assurance that the method is appropriate for all problems. He cited Kaplan’s Law of the Instrument: “Give a boy a hammer and everything he meets has to be pounded.”

Interestingly, this instance did not contain the word “nail”. Instead, the nail was referenced implicitly via the word “hammer” and the verb “to pound”.

Here are additional selected citations in chronological order.

In 1963 a pioneering book titled “Computer Simulation of Personality: Frontier of Psychological Theory” was released, and it consisted of a set of chapters by different authors. The psychologist Silvan Tomkins wrote a passage in the first chapter that used a hammer and nails as part of an analogy that paralleled the adage under study: 4

This was the tendency of jobs to be adapted to tools, rather than adapting tools to jobs. If one has a hammer one tends to look for nails, and if one has a computer with a storage capacity, but no feelings, one is more likely to concern oneself with remembering and with problem solving than with loving and hating.

The 1963 book also contained a chapter by the psychiatrist Kenneth Mark Colby titled “Computer Simulation of a Neurotic Process”. Colby presented a version of the “Law of the Instrument”. The following passage was reprinted when the volume was reviewed in “Science” magazine in November 1963: 5

The First Law of the Instrument states that if you give a boy a hammer, he suddenly finds that everything needs pounding. The computer program may be our current hammer, but it must be tried. One cannot decide from purely armchair considerations whether or not it will be of any value.

In 1964 Abraham Kaplan published “The Conduct of Inquiry: Methodology for Behavioral Science”, and he included a passage about the “Law of the Instrument”: 6

I call it the law of the instrument, and it may be formulated as follows: Give a small boy a hammer, and he will find that everything he encounters needs pounding. It comes as no particular surprise to discover that a scientist formulates problems in a way which requires for their solution just those techniques in which he himself is especially skilled.

In October 1964 Abraham Kaplan published an article in “The Library Quarterly” that also contained pertinent sentences: 7

We tend to formulate our problems in such a way as to make it seem that the solutions to those problems demand precisely what we already happen to have at hand. With respect to the conduct of inquiry, and especially in behavioral science, I label this effect “the law of the instrument.” The simplest formulation I know of the law of the instrument runs this way: give a small boy a hammer and it will turn out that everything he encounters needs pounding.

In 1966 the prominent psychologist Abraham Maslow published “The Psychology of Science: A Reconnaissance”. He presented an instance of the adage that was closer to the common modern versions. The word “nail” was part of this instance: 8

…I remember seeing an elaborate and complicated automatic washing machine for automobiles that did a beautiful job of washing them. But it could do only that, and everything else that got into its clutches was treated as if it were an automobile to be washed. I suppose it is tempting, if the only tool you have is a hammer, to treat everything as if it were a nail.

In 1967 the “Washington Post” reported on remarks made by a powerful U.S. government regulator named Lee Loevinger of the Federal Communications Commission (FCC). Loevinger attached his own name to an instance of the saying: 9

“There is one principle of behavioral science,” Commissioner Loevinger has said, “that has been well established over the years. This is ‘Loevinger’s law of irresistible use’ which says that if a boy has a hammer, this proves something needs pounding. The political science analogue is that if there is a government agency, this proves something needs regulating.”

In September 1974 a columnist for “The Times-Picayune” newspaper of New Orleans, Louisiana printed an instance of the expression that had been sent by an inquirer who was eager to know the identity of the maxim’s creator: 10

Who said “If all you have is a hammer, you treat everything as a nail?” inquired “Puzzled.”

In November 1974 the New Orleans columnist relayed an answer to his readers. The saying was traced back to Abraham Maslow and not to Abraham Kaplan. Also, the wording was slightly altered: 11

MAGICIAN Ernie Heldman turned himself into The Times-Picayune with the source of the quotation: “If the only tool you have is a hammer, you tend to treat everything as if it were a nail.” Abraham Maslow said it in “The Psychology of Science,” published in 1966.

In 1981 the financial advisor Howard J. Ruff published “Survive & Win in the Inflationary Eighties” and the title of the fourth chapter was an instance of the saying: 12

When You Have a Hammer in Your Hand, Everything Looks Like a Nail

In 1982 an MIT professor attributed an instance of the saying to Maslow as reported in the “New York Times”: 13

“Abraham Maslow once said that to him who has only a hammer, the whole world looks like a nail,” said Joseph Weizenbaum, a professor of computer science at M.I.T.

In 1984 the famous investor Warren Buffett used the adage when criticizing academic studies of financial markets that emphasized inappropriate mathematical techniques: 14

It isn’t necessarily because such studies have any utility; it’s simply that the data are there and academicians have worked hard to learn the mathematical skills needed to manipulate them. Once these skills are acquired, it seems sinful not to use them, even if the usage has no utility or negative utility. As a friend said, to a man with a hammer, everything looks like a nail.

By August 1984 the saying had been reassigned to the brilliant humorist Mark Twain. A missive received by the computer periodical “InfoWorld” was printed with the title “Twain Said It”. The letter writer presented an instance with the words “only” and “everything” italicized and credited Twain: 15

For the record, the accurate quote is: “If the only tool you have is a hammer, everything looks like a nail.” I have added emphasis that Mark Twain left to his rhetoric.

In 1985 the award-winning author William Gaddis cleverly permuted the maxim to yield a fresh and emotionally insightful remark for a character in his novel “Carpenter’s Gothic”: 16

…when you feel like a nail everything looks like a hammer…

In 1995 a Florida newspaper printed an instance without attribution and labeled it “an old adage”: 17

“If your only tool is a hammer,” goes an old adage, “then every problem looks like a nail.”

The important 2012 reference work “The Dictionary of Modern Proverbs” from Yale University Press included an entry for this saying that listed the key early citations in the 1960s. 18

In conclusion, by 1962 Abraham Kaplan had formulated a version of the saying featuring a boy that expressed the central idea. However, Kaplan did not use the important word “nail”. In 1963 Silvan Tomkins wrote a version with the word “nail”, but it differed from popular modern instances. In 1966 Abraham Maslow wrote a version that was similar to popular expressions circulating today.

Image Notes: Hammer heads from Practical Blacksmithing (1899) via Wikimedia Commons. Swinging hammer picture is a modified version of the image by geralt on Pixabay.

(Great thanks to Mark Halpern, Benjamin Howard, and Snarxist Agent whose inquiries led QI to formulate this question and perform this exploration. Special thanks to Charles Doyle and his colleagues for their research. Thanks also to John Cowan and Susan Holmberg for their comments. )


  1. 2006, The Quote Verifier by Ralph Keyes, Quote Page 87, St Martin’s Griffin, New York. (Verified on paper)
  2. 1868 April 18, Once a Week, Edited by E. S. Dallas, Number 16, Toys, Start Page 343, Quote Page 344, Column 2, Published by Bradbury, Evans & Company, Fleet Street, London. (Google Books Full View) link
  3. 1962 June, Journal of Medical Education, Volume 37, Trends In Education by Milton J. Horowitz, (Report on the annual meeting of the American Educational Research Association (AERA) held on February 19-21, 1962), Start Page 634, Quote Page 637, Association of American Medical Colleges, Baltimore, Maryland. (Verified on paper)
  4. 1995, Exploring Affect: The Selected Writings of Silvan S Tomkins, Edited by E. Virginia Demos, Series: Studies in Emotion & Social Interaction, (Reprint of article titled: “Simulation of Personality: The Interrelationships Between Affect, Memory, Thinking, Perception, and Action” by Silvan S. Tomkins, Article first appeared in 1963 collection “Computer Simulation of Personality: Frontier of Psychological Theory”, Edited by Silvan S. Tomkins and Samuel Messick; published by Wiley of New York), Start Page 441, Quote Page 445, Cambridge University Press, Cambridge and New York. (Google Books Preview)
  5. 1963 November 8, Science, Volume 142, Number 3593, Book Review: Psychology’s New Frontier by Harold Borko, (Title and authors of book under review: Computer Simulation of Personality by Silvan S. Tomkins and Samuel Messick), Quote Page 656, Column 2, American Association for the Advancement of Science. (JSTOR) link
  6. The Conduct of Inquiry: Methodology for Behavioral Science by Abraham Kaplan, Quote Page 28, Published by Chandler Publishing Company, San Francisco, California. (Verified on paper)
  7. 1964 October, The Library Quarterly, Volume 34, Number 4, “The Age of the Symbol—A Philosophy of Library Education” by Abraham Kaplan, Start Page 295, Quote Page 303, Published by The University of Chicago Press, Chicago, Illinois. (JSTOR) link
  8. 1966, The Psychology of Science: A Reconnaissance by Abraham H. Maslow, Quote Page 15 and 16, Published by Harper & Row, New York. (Verified on paper)
  9. 1967 October 23 Washington Post, FCC Is Divided on Regulating ‘Quality’ by Richard Harwood (Washington Post Staff Writer), Quote Page A22, Column 3, Washington, D.C. (ProQuest)
  10. 1974 September 10, Times-Picayune, Remoulade: Checks May Soon Be Thing of the Past by Howard Jacobs, Quote Page 15, Column 1, New Orleans, Louisiana. (GenealogyBank)
  11. 1974 November 21, Times-Picayune, Remoulade: Today Is Dedicated To Local Versifiers by Howard Jacobs, Quote Page 19, Column 2, New Orleans, Louisiana. (GenealogyBank)
  12. 1981, Survive & Win in the Inflationary Eighties by Howard J. Ruff, (Quote was used as chapter title), Quote Page 44, Target Publishers, San Ramon, California. (Verified with scans)
  13. 1982 April 4, New York Times, Computers Alter Lives of Pupils and Teachers by Edward B. Fiske, Quote Page A1, New York. (ProQuest)
  14. 1984 Fall, Hermes: Columbia Business School, “The Superinvestors of Graham-and-Doddsville” by Warren E. Buffett, Start Page 4, Quote Page 8, Column 1, Published by Columbia Business School of Columbia University, New York. (Note in article: This article is based on a speech Warren Buffett gave at Columbia Business School on May 17, 1984) (Verified with scans)
  15. 1984 August 20, InfoWorld, Volume 6, Number 34, Section: Letters: Twain Said It, (Letter from David Lenfest), Quote Page 6, Column 3, Published by InfoWorld Media Group, Inc. (Google Books Full View)
  16. 1985, Carpenter’s Gothic by William Gaddis, Quote Page 223, Published by Elisabeth Sifton Books: Viking, New York. (Verified with scans)
  17. 1995 October 21, 1995, The News Herald (Panama City News Herald), Section: Viewpoint, “Race relations in U.S.: A dilemma which no commission can solve”, Quote Page 8A, Column 1, Panama City, Florida. (NewspaperArchive)
  18. 2012, The Dictionary of Modern Proverbs, Compiled by Charles Clay Doyle, Wolfgang Mieder, and Fred R. Shapiro, Quote Page 114, Yale University Press, New Haven. (Verified on paper)