Crane's Law: There's No Such Thing as a Free Lunch

Crane's Law is the name Arthur Bloch's Murphy's Law collection gives to a very old piece of folk economics: there is no such thing as a free lunch. Something that looks free has a cost, and if you cannot see who pays it, the answer is usually you, later.

TL;DR Crane's Law says you cannot get something for nothing. The saying comes from the free lunches American saloons once served to drinkers, spread through newspaper columns in the 1930s and 1940s, and was popularized by Robert Heinlein's 1966 novel The Moon Is a Harsh Mistress and Milton Friedman's 1975 essay collection There's No Such Thing as a Free Lunch. The "Crane's Law" label is in print by 1969, and Arthur Bloch's 1977 Murphy's Law collection lists it under that name.

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What Crane's Law says

The archive records the law in its shortest form: There is no such thing as a free lunch. The same idea is written many ways, and all of them mean the same thing:

  • "There ain't no such thing as a free lunch."
  • "There is no such thing as a free lunch."
  • "There's no such thing as a free lunch."
  • "No free lunch."
  • The acronyms TANSTAAFL, TINSTAAFL and TNSTAAFL, which spell out the first three.

A "free" thing is paid for somewhere. The payment may be hidden in a higher price, in your attention, in your data, in a cost passed to someone else, or in a problem you have only postponed.

Where the name comes from

The name is older than Bloch's book. A 1969 article in the journal Pennsylvanian already quotes it as "Crane's Law", and Arthur Bloch's 1977 book Murphy's Law and Other Reasons Why Things Go Wrong lists it under that name.

None of the sources we have checked say who Crane was, so we do not guess. If you know, send us the source and we will add it.

Where the saying comes from

The "lunch" is literal. In the nineteenth-century United States, many saloons offered a free lunch to anyone who bought a drink. The food was often salty, so the customers got thirsty and bought more. Newspapers were already pointing out that the lunch was not free: a South Carolina paper called it one of the most expensive things in town in 1873.

The saying took its modern meaning in print in the 1930s, as the punchline of a short fable, "Economics in Eight Words". A king asks economists to summarize their science, and the last one standing answers in eight words: there is no such thing as free lunch. Wikipedia dates the earliest known telling to a 1933 Cleveland Press column by Herman Fetzer, and says newspaper editor Walter Morrow rewrote it in 1938 with the "ain't" ending. Quote Investigator found no 1933 text, dates the fable to Morrow in June 1938, and calls the case for Fetzer weak, so the exact first appearance is still open.

How it spread

  • 1942: "There ain't no such thing as a free lunch" appears in the trade magazine Public Utilities Fortnightly.
  • 1949: Pierre Dos Utt publishes a monograph titled TANSTAAFL.
  • 1966: Robert A. Heinlein makes TANSTAAFL a central theme of The Moon Is a Harsh Mistress, where a character explains that a bar's free lunch is paid for through its drink prices.
  • 1971: Edwin Dolan's book on environmental policy uses the acronym as its title. The same year, ecologist Barry Commoner's The Closing Circle gives the idea as the last of his four laws of ecology.
  • 1975: Milton Friedman titles a collection of essays There's No Such Thing as a Free Lunch.

Why it belongs with Murphy's Laws

Murphy's Law says that what can go wrong will. Crane's Law explains one of the ways it gets the chance: the cost you did not budget for arrives anyway, usually at a bad moment.

  • The free upgrade that locks you into a new subscription.
  • The quick fix that becomes technical debt.
  • The favor that comes with an invitation to a long meeting.
  • The "free" app that pays for itself with ads or your data.

Economists call the general version opportunity cost: whatever you choose, you give up the next best thing. Ask "what is this costing, and who is paying?" before you accept the lunch and you will meet fewer surprises.

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