Who was the smartest man ever?

The smartest man ever is thought to be William James Sidis. However, there are many other good candidates, like Marilyn vos Savant or Jacob Barnett, just to name a few. Indeed, the number of people who could potentially have an IQ worth of being the smartest in the world ever could be counted in the hundreds (which is not a lot, given that as of today there are 7 billion people on earth) and it would be really difficult to calculate or estimate who of them is really the smartest.

Keep reading to find more about them!

Why is it difficult to know who the smartest person is?

The reason why measuring intelligence (and thus comparing geniuses with one another in order to find out who is smarter) at the extremes becomes more unreliable and has a higher error of measurement is because the sample they can be compared against is smaller.

Intelligence is measured by comparing your performance in a set of cognitive ability items with the performance of all the other test-takers. Your score is derived from the number of correct answers you had relative to the number of correct answers others had.

For instance, if 50% of the population gets 5 or fewer answers correct, that means you are above 50% of people in terms of intellectual ability if you got 6 answers correct.

Roughly speaking, your score is the proportion of people against which you got more correct answers.

For statistical reasons, in order to produce accurate and reliable results, we need large samples of test-takers. The more test-takers against whom your results can be compared, the more accurate these results will be.

However, the more difficult the items get, the fewer people there are that are able to solve them. This means that, for the most difficult items, maybe only 0.1% of test-takers were able to give a correct answer. And these items can still get harder and harder – with fewer and fewer people being able to solve them each time.

This supposes a problem, the smarter you are, the fewer people there are at or close to your level of intellectual ability against whom you can be compared, and therefore the higher the error of measurement is.

At the most extreme levels, there are so few people that drawing any statistical/mathematical comparisons is just not possible, quantifying their intelligence becomes unreliable and loses any statistical sense.

Imagine that there were 100 items in an IQ test, and absolutely no one was able to solve any passed the 70th. If all of a sudden there was someone who solved all of them correctly, how would we know that person’s IQ?

We would know he is above 100% of test-takers, but so would he if he had gotten 71 items correct. How can we know or calculate the difference in terms of IQ between someone who scored 71 items well and someone who scored 100 if there is just no sample in between?

That is exactly the case with profoundly gifted geniuses. They score out of what we are able to measure with our current tests and samples. Even if they do not score out, but just lie around the extremes, the error of measurement would still be high.

The WAIS-IV, one of the most famous and validated IQ tests, only measures up to an IQ of 160.

Either way, we have still done our job, we have researched and gathered a small list of men and women who we think could potentially be among the smartest people on earth. We have included a rough estimate of what we think their IQs are, based on the information that was available on the internet about them.

The smartest people ever on earth:

Marilyn vos Savant – IQ +220

Although there is some controversy as to whether the numbers were exact, when Marilyn took the Standford-Binet test (which is an adult-level IQ test), she got a score of around 220, which landed her in the Guinness World Record. The most striking of all is she was just 10 when that happened. This is also interesting because, in addition, men are supposed to be smarter than women on average when talking about the right extreme of the IQ distribution.

She got even more famous after solving the Monty Hall problem. Indeed, the solution she gave received wild amounts of criticism, some of it even crossing the line towards personal attack.

Many world-class mathematicians and PhDs found themselves writing public apologies some years later when computers proved Marilyn was right.

Marilyn got very famous due to her IQ; she could also be considered one of the celebrities (if she could be regarded as one) with the highest IQs ever.

Jacob Barnett – IQ +180

He was diagnosed with autism when he was just 2. Some doctors even thought he would never be able to even tie his own shoes.

These doctors must have definitely felt very surprised after they found Jacob was accepted into college to study physics at ten, and then graduated at 13.

Before that, he had finished grades six through twelve in less than a year!

As a child, in his leisure time, he used to read physics scientific papers, which is the thing he said he felt passionate about the most.

There is no known record of his IQ, but it must probably be very high, well above 160, given his achievements and extraordinary intellectual skills.

Judit Polgár: IQ +170

Judit Polgár is a worldwide-known chess player, currently considered the best female player to date.

At the early age of 15, she was the youngest chess player to become an International Grandmaster. Impressive!

At 6, her chess rating with the Hungarian chess federation was 2080, and she defeated her first International Grandmaster at 12. She did so at a younger age than Bobby Fischer and Garry Kasparov, who received the title at 14.

It was not possible to find any written record of her IQ, but with such amazing achievements, it is clear she has an intelligence that could easily compete for the title of the “smartest person in the world”.

Magnus Carlsen: IQ +160

He is currently the chess player with the highest ELO of all time.

Carlsen showed an impressive aptitude for intellectual challenges since he was a child. For instance, at 4 he could assemble Lego sets with instructions intended for children aged 10-14.

By age five, he was also able to recall the locations, the populations, the capitals, and the flags of all countries in the world.

William James Sidis: IQ 250-300

Said to be able to speak more than 20 languages as a child, and having been the youngest student to be accepted into Harvard University by age 9, William James Sidis could potentially be one of the smartest persons ever.

He would be teaching at university by age 15, to students much older than him.

However, there are mixed opinions about the veracity of some of these claims, as there has never been found any official basis or proof to support them, such as the one about his wildly high command of so many languages.