"A very small cause which escapes our notice determines a considerable effect that we cannot fail to see, and then we say that the effect is due to chance"
About this Quote
The intent is methodological, but the subtext is philosophical. Poincare is pushing back against the seductive comfort of deterministic storytelling after the fact: we notice outcomes, then retrofit causes. When the true cause is microscopic or buried in a dense system - a tiny measurement error, a subtle initial condition, a stray perturbation - our narratives default to "it just happened". He's warning that the human mind is an unreliable historian of causality, especially in systems where sensitivity amplifies the small into the spectacular.
Context matters: Poincare is writing at the turn of the 20th century, when classical physics still promised clockwork certainty, yet celestial mechanics and nonlinear dynamics were already revealing cracks. His work foreshadows what later gets popularized as chaos theory: deterministic systems can behave unpredictably because minute differences cascade. The quote works because it flips a common intuition. We treat chance as a property of events; Poincare treats it as a property of observers.
Quote Details
| Topic | Free Will & Fate |
|---|---|
| Source | Verified source: Science and Method (Henri Poincare, 1908)
Evidence: A very small cause which escapes our notice determines a considerable effect that we cannot fail to see, and then we say that that effect is due to chance. (Book I (The Scientist and Science), Chapter IV (“Chance”); in the 1914 English translation: p. 68 (printed page), start of §II). This wording is verifiable as a primary-source passage in Henri Poincaré’s Science et méthode (original French edition, 1908; chapter “Le hasard/Chance”). The quote appears early in the “Chance” chapter, immediately after Poincaré’s discussion of unstable equilibrium (a cone balanced on its tip). In the commonly circulated English wording, some versions omit the second “that” ("say that the effect is due to chance"), but the 1914 Francis Maitland translation reads “say that that effect is due to chance.” The original French sentence is: “Une cause très petite, qui nous échappe, détermine un effet considérable que nous ne pouvons pas ne pas voir, et alors nous disons que cet effet est dû au hasard.” (Wikisource transcription available). Other candidates (1) Nonlinear Dynamics and Chaos with Applications to Hydrody... (Slavco Velickov, 2014) compilation97.9% Slavco Velickov. At the turn of the 20th century , Henri Poincaré , another ... A very small cause which escapes our ... |
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Citation Formats
APA Style (7th ed.)
Poincare, Henri. (2026, February 9). A very small cause which escapes our notice determines a considerable effect that we cannot fail to see, and then we say that the effect is due to chance. FixQuotes. https://fixquotes.com/quotes/a-very-small-cause-which-escapes-our-notice-9880/
Chicago Style
Poincare, Henri. "A very small cause which escapes our notice determines a considerable effect that we cannot fail to see, and then we say that the effect is due to chance." FixQuotes. February 9, 2026. https://fixquotes.com/quotes/a-very-small-cause-which-escapes-our-notice-9880/.
MLA Style (9th ed.)
"A very small cause which escapes our notice determines a considerable effect that we cannot fail to see, and then we say that the effect is due to chance." FixQuotes, 9 Feb. 2026, https://fixquotes.com/quotes/a-very-small-cause-which-escapes-our-notice-9880/. Accessed 12 Feb. 2026.













