Variant: The problem with the world is that the intelligent people are full of doubts, while the stupid ones are full of confidence.
Original: Le persone intelligenti, dubitano. Sempre.
Source: prevale.net
Variant: The problem with the world is that the intelligent people are full of doubts, while the stupid ones are full of confidence.
“Doubt is one of the names of intelligence.”
La duda es uno de los nombres de la inteligencia.
As quoted in Diccionario privado de Jorge Luis Borges (1979) edited by Blas Matamoro
Powell told David Frost in a BBC television interview
Quoted in Breaking Ranks Larry Wilkerson Attacked the Iraq War. In the Process, He Lost the Friendship of Colin Powell. https://www.washingtonpost.com/archive/lifestyle/2006/01/19/breaking-ranks-span-classbankheadlarry-wilkerson-attacked-the-iraq-war-in-the-process-he-lost-the-friendship-of-colin-powellspan/d1f359c6-93a0-41c1-beee-2284d6284d47/ Washington Post, by Richard Lei (19 January 2006)
2000s
“Headmaster: They were all socialists. Why is it always the intelligent people who are socialists?”
Act 2, p. 75.
Of the Bloomsbury group.
Forty Years On (1972)
The Freethinker (1970), G.W. Foote & Company, Volume 90, p. 147.
Date unknown
Often paraphrased as "The whole problem with the world is that fools and fanatics are always so certain of themselves, but wiser people so full of doubts."
Compare: "One of the painful things about our time is that those who feel certainty are stupid, and those with any imagination and understanding are filled with doubt and indecision." B. Russell, New Hopes for a Changing World (1951). Compare also: "The best lack all conviction, while the worst / Are full of passionate intensity." W. B. Yeats, The Second Coming (1919).
See also: Dunning-Kruger effect, Historical Antecedents https://en.wikipedia.org/wiki/Dunning–Kruger_effect#Historical_antecedents.
1930s, Mortals and Others (1931-35)