"The first principle is that you must not fool yourself and you are the easiest person to fool"
About this Quote
The intent is disciplinary, almost ascetic. Feynman isn’t praising skepticism as a personality trait; he’s prescribing it as a method. This comes straight out of his “cargo cult science” critique, where he warned against research that mimics the outer rituals of rigor while quietly dodging the inner obligation: to test your own favorite hypothesis as if you wanted it to fail. The subtext is that institutions, careers, and prestige make self-deception easier, not harder. When your identity is tied to being right, you’ll unconsciously curate evidence, soften inconvenient results, and confuse elegance for truth.
Stylistically, it works because it’s plainspoken and ruthless. No grand metaphysics, just a single, memorable imperative that re-centers integrity on the private moment before publication: what you allow yourself to believe. In an era of incentives, hot takes, and confirmation-by-algorithm, Feynman’s warning reads less like a scientist’s aphorism and more like a survival manual for thinking.
Quote Details
| Topic | Truth |
|---|---|
| Source | Help us find the source |
| Cite |
Citation Formats
APA Style (7th ed.)
Feynman, Richard P. (2026, January 15). The first principle is that you must not fool yourself and you are the easiest person to fool. FixQuotes. https://fixquotes.com/quotes/the-first-principle-is-that-you-must-not-fool-25401/
Chicago Style
Feynman, Richard P. "The first principle is that you must not fool yourself and you are the easiest person to fool." FixQuotes. January 15, 2026. https://fixquotes.com/quotes/the-first-principle-is-that-you-must-not-fool-25401/.
MLA Style (9th ed.)
"The first principle is that you must not fool yourself and you are the easiest person to fool." FixQuotes, 15 Jan. 2026, https://fixquotes.com/quotes/the-first-principle-is-that-you-must-not-fool-25401/. Accessed 6 Feb. 2026.













