Explain it to me like I’m a 4-year-old

In the 1993 courtroom drama Philadelphia, Joe Miller, played by Denzel Washington, defends HIV-positive lawyer Andrew Beckett, played by Tom Hanks. Beckett worked in a large law firm until his boss discovers that Beckett has AIDS and fires him. When Beckett approaches Miller to represent him in a lawsuit against his employer, Miller replies, “All right, explain this to me like I'm a 4-year-old. OK, because this element to this thing I just cannot get through my thick head. Didn't you have an obligation to tell your employer you had this dreaded, deadly, infectious disease?” Becket defends himself but Miller leans back and tells him: “I don't buy it, counselor. I don't see the case.” Nevertheless, Miller changes his mind and decides to help Beckett.

The quote "Explain it to me like I'm a 4-year-old" appears several times in the film, although the ages do vary. The quote transcends this Oscar-winning courtroom drama. It is not only a reference to expensive lawyers who try to win a case with file-busting and legal cleverness. It is also an oft-heard cri de coeur from entrepreneurs, managers, policymakers and other professionals who are tired of the empty phrases of management bullshit and want to grasp a subject in a clear, understandable way. But how do you explain complex concepts such as net present value, subsidiarity principle or unconditional love in an understandable way? It seems that it takes more insight from a person to explain something simple than something complex. Perhaps that is why Einstein is reported to have said: "If you can't explain it to a six-year-old, you don't understand it well enough".

This legend is about Albert Einstein. During his lifetime, he gave many lectures on his difficult to grasp theory of relativity. During these lectures, he was always accompanied by his chauffeur, who waited at the back of the room for the evening to end. After some time, the driver said: "Professor Einstein, now I have heard your lecture on the theory of relativity so often that if I ever had the opportunity, I could explain it perfectly myself." "Very well," replied an amused Einstein, "next week we'll go to a place where they don't know me. Then you can be at the front." And so it happened. Entering the hall, Einstein took the driver's cap and sat down at the back. The driver had no problem reciting the lecture on the theory of relativity perfectly, much to Einstein's delight. After the lecture, an attendee raised his hand and asked him a tricky question, full of complicated calculations and equations. But the driver answered without hesitation: "My dear man, the answer to this question is very simple. So simple, in fact, that I am now asking my driver at the back of the room to answer it!"

The driver was able to solve the tricky situation via a clever ruse, but he had to admit afterwards that there is a big difference between memorising a lecture and then rattling it off and understanding a subject in depth. Belgian scientist and media personality Lieven Scheire summarises the theory of relativity in the following two sentences (watch his explanation here): "When you travel at a really high speed, time slows down. And when you travel at really high speed, lengths become shorter". These sentences are very clear. But do you also understand that if I were to get into a ten-meter rocket and fly around the sun at a speed of 290,000 km per second for two years and then return to earth, that for me two years will have passed and for you on earth 40 years? And that while I am flying there and you are measuring my rocket, my rocket is not ten meters long, but only three?

The growth of science and knowledge is phenomenal and no one can grasp knowledge like an uomo universalis like Leonardo Da Vinci did. In his 1982 book "Critical Path", futurist and inventor R. Buckminster Fuller estimated that if we were to equate all the knowledge accumulated by mankind by the year one A.D. with one unit of information, it probably took about 1500 years or until the sixteenth century to double that amount of knowledge. The next doubling of knowledge from two to four "units of knowledge" took only 250 years until about 1750. By 1900, 150 years later, knowledge had doubled again to eight units. Today, the rate of doubling is between one and two years.

We live in a world where people trust science, knowledge and technology and use them blindly. In their book "The knowledge illusion: why we never think alone", professors Steven Sloman and Philip Fernbach give the example of toilets. Everyone knows the phenomenon of a toilet: a ceramic bowl filled with water. You press a button or a lever and the water, and everything in it, is sucked into a pipe and discharged into a sewer. But how exactly does this work? A group of Yale students were asked to rate their knowledge of some everyday objects (such as a toilet, a zipper or a cylinder lock) on a scale of ten. They were then asked to describe in detail how these objects function. This seemed much more difficult than expected. The professors attribute this overestimation to the fact that people trust in the knowledge of others and do not draw a sharp line between their own knowledge and the knowledge of the group.

Who can still explain how a car moves? Why can an airplane fly? Why does a cow give milk? Toddlers bombard us with these why questions, but as adults we rely on the knowledge of the group and have stopped asking ourselves these questions. And so we talk in a language full of inadequate, meaningless generalities to hide our lack of understanding. Until, during a conversation or a meeting, you exclaim: "Explain it to me like I'm a 4-year-old!".

The American physicist and Nobel Prize winner Robert Feynman was nicknamed "The Great Explainer". He often emphasised the difference between knowing something by name and really knowing it. A name is just a box and you have to look inside the box. If you really know something, then you can break that knowledge down into pieces and make new connections. He writes: "See that bird? It's a brow-throated trush, but in Germany it's called a halzenfugel, and in Chinese they call it a chung ling, and even if you know all those names for it, you still know nothing about the bird. You only know something about people: what they call the bird. Now that thrush sings, and teaches its young to fly, and flies so many miles away during the summer across the country, and nobody knows how it finds its way."

If you write down an idea from beginning to end in simple language that a child can understand, you force yourself to grasp the concept at a deeper level and establish relationships and connections between the different ideas. This way, you don't get stuck in the "what", but you can better explain the "why". That is the essence of the Feynman technique.

And yet, human knowledge is so fragile, sighs Richard Feynman in his book Surely, You're joking, Mr Feynman. He cites the example of an assistant to Einstein, who for years had been studying the knowledge of gravity. Feynman presented him with the following problem: you shoot away in a rocket with a clock on board and there is a clock on the ground. The challenge is that you have to be back down when the clock on the ground indicates that exactly one hour has passed. At what speed should you fly and to what altitude? Einstein's assistant immediately started to perform all sorts of calculations and only after a while realised that you could easily solve the riddle with one of Einstein's fundamental principles of the theory of relativity, namely the present time. Feynman concludes: “I don't know what's the matter with people: they don't learn by understanding; they learn by some other way, by rote, or something. Their knowledge is so fragile”.

According to a 2013 study, four-year-old girls ask 390 questions a day... So let the child in you loose and ask the why question at least ten times a day!