The Bonhoeffer Reader https://www.google.com/books/edition/The_Bonhoeffer_Reader/CNZgAwAAQBAJ?hl=en&gbpv=1&pg=PA766, p. 766
Letters and Papers from Prison (1967; 1997), On Stupidity
“Convictions are more dangerous enemies of truth than lies.”
Section IX, "Man Alone with Himself" / aphorism 483
Human, All Too Human (1878), Helen Zimmern translation
Context: Enemies of truth. Convictions are more dangerous enemies of truth than lies.
“An enemy forgiven is more dangerous than a thousand foes.”
Quoted in "The Suez Canal in World Affairs" - Page 79 - by Hugh Joseph Schonfield - 1952
“Nothing in the world is more dangerous than sincere ignorance and conscientious stupidity.”
Source: 1960s, Strength to Love (1963), Ch. 4 : Love in action, Sct. 3
“There’s nothing more dangerous than a good idea.”
Ron English's Fauxlosophy (2016)
“Never ascribe to malice that which is adequately explained by stupidity.”
Often known as Hanlon's razor, this was attributed to Napoleon without source in Message Passing Server Internals (2003) by Bill Blunden, p. 15, ISBN 0071416382
Misattributed
“Never attribute to malice that which is adequately explained by stupidity.”
Murphy's Law Book Two : More Reasons Why Things Go Wrong! (1980) ISBN 0843106743 by Arthur Bloch page 52.
This statement has often been referred to as Hanlon's Razor, though the author himself has remained relatively unknown, and some theories arose that "Hanlon" might have been a corruption of "Heinlein". Hanlon actually was a winner in a contest to come up with further statements similar to "Murphy's Law", for publication in this particular book. This phrase or very similar statements have also been attributed to William James, Napoleon Bonaparte, Richard Feynman (who might well have quoted it) and others.
Similar statements have been made by Goethe, and indeed, Robert Heinlein:
In The Sorrows of Young Werther Goethe declared, "Misunderstandings and neglect occasion more mischief in the world than even malice and wickedness. At all events, the two latter are of less frequent occurrence."
In his story Logic of Empire (1941) Heinlein declares: "You have attributed conditions to villainy that simply result from stupidity". He calls this the "devil theory" of sociology. His character Lazarus Long also voices a variation on the theme in the novel Time Enough for Love: "Never underestimate the power of human stupidity."
Variants of the phrase which have been variously attributed to this wide assortment of authors include:
Never ascribe to malice that which can be adequately explained by stupidity.
Never ascribe to malice that which can be explained by incompetence.
Never ascribe to malice that which is adequately explained by stupidity.
“There is no more sombre enemy of good art than the pram in the hall.”
Source: Enemies of Promise (1938), Part 2: The Charlock’s Shade, Ch. 14: The Charlock’s Shade (p. 116)
Tomorrow and Tomorrow and Tomorrow (1952)
Source: Complete Essays 1, 1920-25
“Folly is often more cruel in the consequence, than malice can be in the intent.”
Political, Moral, and Miscellaneous Reflections (1750), Moral Thoughts and Reflections
