Never attribute to malice that which is adequately explained by stupidity.
(Other Authors and Sources)
Robert J. Hanlon, “Hanlon’s Razor,” Murphy’s Law, Book Two (ed. A. Bloch) (1980)
Cf. Heinlein (again), Napoleon, Taylor, Bonhoeffer, Colton, and Goethe.
See here for more information, including discussion that "Robert J. Hanlon" may be a corruption or obfuscation of "Robert A. Heinlein."
Various variants in combinations with "ascribe," "what can be," and "incompetence."
Variant ("Aerospace saying"): "Never ascribe something to another cause that can be fully explained by stupidity and mediocrity."
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