EP 13: Richard Feynman Famous Quote “The first principle is that you must not fool yourself, and you are the easiest person to fool”

In this episode of the Merkol Podcast, we analyzed the Richard Feynman Famous Quote. The quote goes:

“The first principle is that you must not fool yourself, and you are the easiest person to fool”

Richard Feynman Famous Quote
Richard Feynman Famous Quote
Richard Feynman Famous Quote

Who is Richard Feynman?

The below excerpts are taken from Wikipedia, Farnam Street blog, and MacTutor.

Richard Phillips Feynman was born on May 11, 1918, in Queens, New York City, to Lucille Phillips and Melville Arthur Feynman.

The young Feynman was heavily influenced by his father, who encouraged him to ask questions to challenge orthodox thinking, and who was always ready to teach Feynman something new. From his mother, he gained the sense of humor that he had throughout his life.

As a child, he had a talent for engineering, maintained an experimental laboratory in his home, and was delighted in repairing radios. When he was in grade school, he created a home burglar alarm system while his parents were out for the day running errands.

He studied a lot of mathematics in his own time including trigonometry, differential and integral calculus, and complex numbers long before he met these topics in his formal education. Realizing the importance of mathematical notation, he invented his own notation for sin, cos, tan, f (x)f(x), etc. which he thought was much better than the standard notation. However, when a friend asked him to explain a piece of mathematics, he suddenly realized that notation could not be a personal matter since one needed it to communicate.

Feynman also worked on the Manhattan project in 1941. The Manhattan Project was the code name for the American-led effort to develop a functional atomic weapon during World War II.

Feynman was never one to settle for knowing the description of things or the accepted truths of things. Instead, he really wanted to know, and it was that burning curiosity that led him to his greatest work. Feynman was human, at times all too human, but his mind was devoted to figuring out reality the way it was.

Richard Feynman Famous Quote: What does it mean?

To understand this quote better we need to understand the concept of confirmation bias. It is the tendency to interpret new evidence as confirmation of one’s existing beliefs or theories.

For example, consider someone who believes that people who are left-handed are more creative than persons who are right-handed. When this individual meets someone who is both left-handed and creative, they place a larger emphasis on the “proof” that backs up their beliefs. This person may go so far as to seek proof that supports their belief while dismissing examples that contradict it.

Confirmation biases affect not only how we receive information, but also how we understand and retain it. People who support or oppose a certain subject, for example, will not only seek information to support their position but will also interpret news stories to support their previous beliefs. They’ll also recall details in a way that promotes their beliefs.

This tendency is present in all of us. Thala Ajith vs Thalapathy Vijay fan fight is an excellent example of this. Both sets of fans understand the greatness of the other person, but still only seek to look at or acknowledge the information that confirms the side you choose. It is the same with Messi Vs Ronaldo.

Richard Phillips Feynman
Richard Phillips Feynman

In this case, no one is forcing you to agree or disagree with anything. You have chosen a side because of your natural instincts and you try to fight for it by looking for evidence that proves your theory. This is normal and is a basic human trait, but the point where we become fools is when we don’t acknowledge or disapprove of other pieces of evidence just so that we can prove our theory.

People who are not aware that they are doing this would live their entire lives like this and the worst part is they start not seeing anything that disapproves of their notions, let alone considering them.

In extreme forms, people will accept very poor quality evidence and even exaggerate its importance in order to support their theories.

This is the main reason behind people supporting corrupt political leaders even when there is mounting evidence that he/she is corrupt. Yet their minds are trained by themselves to not consider those evidence and just look for proof that confirms their beliefs.

This was how Feynman approached all knowledge: What can I know for sure, and how can I come to know it? It resulted in his famous quote, “You must not fool yourself, and you are the easiest person to fool.” Feynman believed it and practiced it in all of his intellectual work.

The only to avoid this confirmation bias is to train ourselves to challenge what we think we see. Seek out information from a range of sources.

Alternatively, discuss your thoughts with others. Surround yourself with a diverse group of people, and don’t be afraid to listen to dissenting views.


What we take from Feynman is an absolute, unvarying pursuit of rationality and truth. Feynman would rather admit that he didn’t know something than believe in false knowledge.

Always approach any problem with no preconceived notions and try to understand it completely. Even then don’t make any conclusions. Let your findings speak for themselves.


I have recorded a podcast on this Richard Feynman Famous Quote. But it is in Tamil. If you know the language then please do listen to this. Do let me know if you like it. Here is the link:

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