Yet she stands by her answer.
And she is right.
Marilyn vos Savant was born Marilyn Mach on 11 August 1946 in St Louis, Missouri. As a child, she stood out for her extraordinary intelligence. At the age of ten, she took an earlier version of the Stanford-Binet test. The result, calculated using the ‘mental age’ method in use at the time, yielded the spectacular figure of 228.
This score earned her a place in the Guinness Book of Records for several years as the holder of the ‘highest IQ’. The category was eventually discontinued in 1990, as the tests were considered too varied and too imprecise to seriously designate one person as the most intelligent in the world.
We must therefore immediately dispel some of the folklore surrounding her story. Marilyn vos Savant has not scientifically demonstrated that she is more intelligent than Albert Einstein or Stephen Hawking. As for the figures regularly attributed to Einstein, Hawking or Elon Musk on social media, they are generally wild guesses, or even outright fabrications.
But Marilyn vos Savant did not need an artificial comparison to be fascinating.
After putting her philosophy studies on hold to work in the family business, she moved to New York and devoted herself to writing. Her fame earned her a column in *Parade*, a huge Sunday supplement distributed with hundreds of American newspapers. From 1986 onwards, she answered readers’ questions there, solved puzzles and debunked a few misleading lines of reasoning.
On 9 September 1990, a reader submitted a probability problem inspired by the American game show ‘Let’s Make a Deal’, formerly presented by Monty Hall.
The contestant stands before three doors. Behind one of them is a car. Behind the other two are goats.
The contestant chooses a door, but it remains closed. The presenter, who knows where the car is, then opens one of the other two doors and reveals a goat. He then offers the contestant the choice of sticking with their original choice or switching to the last door, which is still closed.
Should the contestant switch doors?
Our immediate intuition tells us that there are two doors left and that there is therefore a one-in-two chance of winning. Switching or not switching would make no difference.
Marilyn vos Savant, however, replies that the contestant should switch. By sticking with their first door, the contestant has only a one-in-three chance of winning. By choosing the other one, they have a two-in-three chance.
The car has obviously not moved, and no magical probability has been added to the game. When making their first choice, the contestant had only a one-in-three chance of picking the car. They therefore had a two-in-three chance of choosing a goat.
The presenter knows the correct answer. He does not open a door at random: he deliberately eliminates a losing door. If the contestant’s first choice was wrong — which happens two times out of three — the car must necessarily be behind the only other door still closed.
Swapping therefore guarantees a win whenever the first choice was wrong, i.e. in two out of three cases.
The mechanism becomes even clearer if we imagine a hundred doors. The contestant chooses one, with only a one-in-a-hundred chance of having found the car. The presenter then opens ninety-eight doors, all of which contain a goat. All that remains is the door chosen at the start and one other closed door.
Who would really want to stick with their first choice, made almost entirely at random?
Marilyn vos Savant’s answer, however, sparked a national outcry. *Parade* received around ten thousand letters of protest. Nearly a thousand were signed by people holding a PhD, sometimes written on the letterhead of university departments of mathematics or science.
Some correspondents did not merely challenge her reasoning. They addressed her with brutal condescension. Others openly brought her gender into their criticism, as if the error they believed they had uncovered proved something about women and mathematics.
Marilyn vos Savant did not back down.
She reiterates her explanation, provides tables of results and invites teachers to replicate the experiment with their pupils. The simulations confirm what she has been asserting from the outset: over a large number of rounds, the strategy of switching doors wins about two-thirds of the cars.
One important clarification remains essential. Her solution assumes that the presenter knows the location of the car, always opens a losing door and systematically offers the contestant the chance to switch. If the presenter acts at random or only offers the switch in certain situations, the probabilities may differ.
In the classic version of the Monty Hall problem – the one that has been heard around the world – Marilyn vos Savant was indeed correct.
This story does not prove that an extremely intelligent person is never wrong. Indeed, Marilyn vos Savant has been challenged – sometimes justifiably – on other subjects. It demonstrates something even more unsettling: the accumulation of degrees, titles and certainties does not protect against misleading intuition.
A thousand doctorates do not turn a mistake into the truth.
It also shows just how difficult it can be for a woman to be right in a setting where certain men regard themselves as the natural custodians of knowledge. Many of her opponents did not merely counter her with a calculation. They asked her to fall into line, to abandon her reasoning in the face of the social weight of their authority.
She preferred to count the doors.
What is perhaps most remarkable about Marilyn vos Savant is therefore not her famous IQ of 228. This spectacular figure is based on an outdated method of measurement and does not allow for a credible ranking of the greatest minds in history.
Her true achievement was far more human.
She observed a problem that almost everyone believed they understood. She accepted that the truth might run counter to the obvious. Then, standing before ten thousand people certain of their own superiority, she did not confuse the number of her opponents with the strength of their arguments.
Intelligence sometimes begins like this: standing alone before three doors and continuing to see what others still refuse to look at.
