Blockchain/Level I · Money/1.1 What money is/Lesson 1
Barter and the coincidence of wants
The friction money removes, and the myth about where it came from
MaterialsA notebookThree or four household items to price against one another
Wonder
- Two people each hold something the other could use. Why might no trade happen?
- If barter is so clumsy, why does it reappear whenever a currency fails?
- Did money grow out of barter, or out of something else?
Explore
- Direct exchange works only when each party wants what the other has, in the quantity offered, at the same time and place. William Stanley Jevons called it a “double coincidence, which will rarely happen” in Money and the Mechanism of Exchange (1875); later writers made it the “double coincidence of wants.” A baker who needs shoes must find a shoemaker who needs bread today; if the shoemaker wants cheese, the baker has to arrange a chain of trades to get there.
- The friction compounds. With n goods in a market there are n(n−1)/2 exchange ratios to track: 45 for ten goods, 4,950 for a hundred. Indivisible goods make it worse; a cow cannot be split to pay for sandals without destroying its value. Barter also offers no clean way to save, because stored goods spoil, need housing, or lose their buyers.
- Money splits one exchange into two. The baker sells bread for money now and buys shoes later, from anyone, anywhere. A single accepted good also becomes the unit of account: every price is quoted in the same terms, and the bookkeeping problem collapses from thousands of ratios to one list of prices.
- Adam Smith (1776) and Carl Menger (1892) told the story as a sequence: barter first, then intolerable friction, then money. Anthropologists have not found that sequence. Caroline Humphrey wrote in 1985 that “no example of a barter economy, pure and simple, has ever been described, let alone the emergence from it of money.” Small communities ran on gift, obligation and remembered credit; Mesopotamian temples kept accounts in barley, and later silver, long before coins existed.
- Barter appears instead at the edges: between strangers who will not meet again, and where money has failed. R. A. Radford’s 1945 account of prisoner-of-war camps describes cigarettes becoming the currency, with prices that rose and fell as Red Cross parcels arrived. Argentina’s barter clubs, founded in 1995 with their own paper créditos, swelled to millions of members in the 2001–02 crisis, then collapsed as the notes were counterfeited. People who lose a trusted money rebuild one quickly, and the new one faces the same tests.
- Both accounts point to the same function. Whether money grew from barter or from credit ledgers, it lets strangers settle across time and distance without relying on each other’s memory or goodwill. Every later money, from shells to gold to paper to bitcoin, has to answer the same question: what makes that settlement reliable?
Key facts
- Jevons (1875) described barter’s requirement as a “double coincidence”; the phrase “double coincidence of wants” came later.
- Barter among n goods needs n(n−1)/2 exchange ratios; a common unit of account reduces this to n prices.
- Money separates selling from buying in time, place and counterparty.
- Anthropologist Caroline Humphrey (1985): no pure barter economy has ever been documented.
- Mesopotamian temples kept barley accounts more than two thousand years before the first coins.
- Improvised currencies, such as cigarettes in WWII prison camps and the créditos of Argentina’s barter clubs, appear when trusted money is missing or failing.
Exercise nine, six, three, one
9CollectList 9 exchanges you have made without money: favors, swaps, shared meals, borrowed tools. Note what was given, what came back, and how long the gap was.
6ClusterSort the 9 into 6 groups by what kept each exchange honest: memory, reputation, family tie, written record, immediate swap, or something else.
3DistillReduce the 6 to 3 conditions under which money-free exchange works, and note where each one breaks down.
1CrystallizeWrite 1 sentence on what money adds that memory and goodwill cannot.
Fact check
Dates, figures and claims checked against the published sources listed below.
- W. S. Jevons, Money and the Mechanism of Exchange (1875)
- A. Smith, The Wealth of Nations (1776), Book I ch. 4
- C. Menger, "On the Origins of Money", Economic Journal (1892)
- C. Humphrey, "Barter and Economic Disintegration", Man (1985)
- R. A. Radford, "The Economic Organisation of a P.O.W. Camp", Economica (1945)
- D. Graeber, Debt: The First 5,000 Years (2011)