Hanlon's razor is an aphorism expressed in various ways, including:
- "Never attribute to malice that which is adequately explained by stupidity."
Inspired by Occam's razor, the aphorism was popularized in this form and under this name by the Jargon File, a glossary of computer programmer slang. Later that same year, the Jargon File editors noted lack of knowledge about the term's derivation and the existence of a similar epigram by William James. In 1996, the Jargon File entry on Hanlon's Razor noted the existence of a similar quotation in Robert A. Heinlein's novella Logic of Empire (1941), with speculation that Hanlon's Razor might be a corruption of "Heinlein's Razor". (The character "Doc" in Heinlein's story described the "devil theory" fallacy, explaining, "You have attributed conditions to villainy that simply result from stupidity.")
In 2001, Quentin Stafford-Fraser published two blog entries citing e-mails from Joseph E. Bigler explaining that the quotation originally came from Robert J. Hanlon of Scranton, Pennsylvania, as a submission (credited in print) for a book compilation of various jokes related to Murphy's law published in Arthur Bloch's Murphy's Law Book Two: More Reasons Why Things Go Wrong! (1980). Subsequently, in 2002, the Jargon File entry noted the same.
- Newton's Flaming Laser Sword
- Clarke's three laws
- Dunning–Kruger effect – Cognitive bias in which people of low ability mistakenly assess their cognitive ability as greater than it is
- Finagle's law
- Good faith
- Hitchens's razor
- Occam's razor – Philosophical principle of selecting the solution with the fewest assumptions
- Law of triviality
- Peter principle
- Presumption of innocence
- Principle of charity
- Sturgeon's law
- Guy L. Steele; Eric S. Raymond, eds. (1990-06-12). "The Jargon File, Version 2.1.1 (Draft)". jargon-file.org. Retrieved 2017-07-19.
- Livraghi, Giancarlo (2004). Il potere della stupidità. Pescara, Italy: Monti & Ambrosini SRL. p. 1. ISBN 9788889479131.
- "Hanlon's Razor". Jargon File. Eric S. Raymond. 2002-03-03. Retrieved 2017-07-19.
- Eric S. Raymond; Guy L. Steele, eds. (1990-12-15). "The Jargon File, Version 2.2.1". jargon-file.org. Retrieved 2017-07-19.
- Eric S. Raymond, ed. (1996-07-24). "The Jargon File, Version 4.0.0". jargon-file.org. Retrieved 2017-07-19.
- Robert Heinlein (1941-03-01). "Logic of Empire". Astounding Science-Fiction. Vol. 27 no. 1. p. 39. Retrieved 2018-08-08.
- Stafford-Fraser, Quentin (2001-11-26). "[untitled]". Retrieved 2017-07-19.
- Stafford-Fraser, Quentin (2001-12-04). "The origins of Hanlon's Razor". Retrieved 2017-07-19.
- Arthur Bloch (1980). Murphy's Law Book Two: More Reasons Why Things Go Wrong!. Price Stern Sloan. p. 52. ISBN 9780417064505.
- Eric S. Raymond, ed. (2002-03-03). "The Jargon File, Version 4.3.2". jargon-file.org. Retrieved 2017-07-19.