Benjamin Franklin's IQ: The 1926 Estimate and the Record Behind It

What the 1926 Stanford study found

Franklin is one of the 301 subjects in Catharine Cox's The Early Mental Traits of Three Hundred Geniuses, the second volume of Lewis Terman's Genetic Studies of Genius, published by Stanford University Press in 1926. Cox, Terman and Maud Merrill read condensed biographies of each subject and asked one question: what IQ would a child have needed to do what this person did at the same age?

Cox produced two estimates per person. The first covers birth to 17; the second covers ages 17 to 26. Franklin's case sits in her chapter for subjects rated 140 to 150 on childhood evidence. For ages 17 to 26 her raters recorded 145. Cox then adjusted every figure for the reliability of the evidence behind it, and Franklin's corrected young-adult estimate is 160 — the number most lists repeat.

His full profile is at Benjamin Franklin. The logic and limits of the Cox method are laid out in historical IQ estimates, explained.

Two years of school, then a self-built education

Franklin's schooling ran from age eight to ten. "At ten years old I was taken home to assist my father in his business," he wrote in his autobiography. At 12 he was apprenticed to his brother James, a Boston printer. At 16, in 1722, he slipped the Silence Dogood letters, written under a pseudonym, into his brother's New-England Courant.

He trained his prose by taking notes on essays from the Spectator, rebuilding them from memory and checking his version against the original to find his faults. He taught himself languages the same way. "I had begun in 1733 to study languages," he recorded. French came first, then Italian and Spanish. When he later opened a Latin Testament, he found he understood far more than one boyhood year of Latin school should have allowed.

That is the kind of record Cox's raters scored highest: early, independent, and documented in the subject's own hand.

The electrician who named the parts

Franklin's scientific standing does not rest on a kite legend. Experiments and Observations on Electricity, published in 1751, set out his account of electrical charge and argued that lightning is electrical. The kite test followed in June 1752. He invented the lightning rod, and rods went up on the Academy of Philadelphia and the Pennsylvania State House that same year.

He also supplied the vocabulary. Terms credited to him include battery, charge, conductor, plus, minus, positively and negatively. The Royal Society awarded him the Copley Medal in 1753 and elected him a Fellow in 1756. Harvard and Yale granted him honorary degrees in 1753, St Andrews in 1759 and Oxford in 1762. The man who left school at ten became "Dr. Franklin."

Where he stands among scientists is covered in physicists ranked by estimated IQ.

Range: printer, founder, diplomat, mapmaker

Breadth drove Franklin's rating. He published Poor Richard's Almanack from 1732 under the name Richard Saunders. He founded the Library Company of Philadelphia in 1731 and the American Philosophical Society in 1743, and served as first president of the Academy of Philadelphia, forerunner of the University of Pennsylvania, from 1749. In 1770 he published a chart of the Gulf Stream.

Politics came late and ran deep. Franklin is the only person to sign the Declaration of Independence, the 1783 Treaty of Paris with Britain, and the Constitution. He was 81 when he signed the last of them.

How Franklin compares with other founders

On Cox's figures, Franklin shares the top of the founding generation with Jefferson and Madison. John Quincy Adams, of the next generation, rates higher at 175.

Five-point gaps are smaller than the uncertainty in any single estimate, so the table ranks evidence, not brains. For a head-to-head on achievement, see Jefferson vs. Franklin.

What 160 does and does not mean

Cox's figures measure documentation as much as mind. A subject with a rich childhood record, and Franklin wrote his own, can outscore an equally able person whose early years went unrecorded. Cox knew this; her corrections exist to offset it. Treat 160 as an informed estimate with a wide margin. Even a modern test score carries a band of roughly five points either way, and Franklin's number has no test behind it at all. For what the figure would mean on today's scale, see IQ 160.

A second caution concerns a smaller number. Some comparison sites subtract about 22 points for the Flynn effect, the rise in test scores across the 20th century, and list Franklin at 138. Cox made no such adjustment. Applying a modern population trend to one 18th-century man stacks a second guess on top of the first.

How we assessed this

We located Franklin's case in the table of contents of Cox's 1926 volume, took his corrected figure from a published reproduction of her Table 12A, and confirmed that the same reproduction matches Dean Keith Simonton's 2006 figures for six presidents Cox also rated. Biographical dates come from Franklin's autobiography, Wikipedia's sourced biography and the Independence Hall Association's account of his electrical work.

Editorial standard: IQ figures for historical figures are retrospective estimates and are labeled as such; scores for living people appear only when the person disclosed them or a reputable outlet reported them. Corrections: contact the editors.