Hanlon's razor

Hanlon's razor is an adage, or rule of thumb, that states: "Never attribute to malice that which is adequately explained by stupidity."^[1] It is a philosophical razor that suggests a way of eliminating unlikely explanations for human behavior. It is purportedly named after one Robert J. Hanlon,^[2] who submitted the statement to Murphy's Law Book Two: More Reasons Why Things Go Wrong! (1980).^[1] Similar statements have been recorded since at least the 18th century.

The adage was a submission credited in print to Robert J. Hanlon of Scranton, Pennsylvania,^[2] in a 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).^[1]

A similar quotation appears in Robert A. Heinlein's 1941 novella "Logic of Empire".^[3] The character Doc in the story describes the "devil theory" fallacy, explaining, "You have attributed conditions to villainy that simply result from stupidity."^[4]

Hanlon's razor became well known after its inclusion in the Jargon File, a glossary of computer programmer slang, in 1990.^[5] Later that year, the Jargon File editors noted lack of knowledge of the term's derivation and the existence of a similar epigram by William James, although this was possibly intended as a reference to William James Laidlay.^[6][7] In 1996, the Jargon File entry on Hanlon's Razor noted the existence of the phrase in Heinlein's novella, with speculation that Hanlon's Razor might be a corruption of "Heinlein's Razor".^[3] The link to Murphy's law was described in a pair of 2001 blog entries by Quentin Stafford-Fraser, citing emails from Joseph E. Bigler.^[8][9] In 2002, the Jargon File entry noted the same.^[10] The Jargon File now calls it a "Murphyism".^[2]

The name was inspired by Occam's razor.^[11]

Grey's law (a humorous parallel to Arthur C. Clarke's 3rd law):

Any sufficiently advanced incompetence is indistinguishable from malice.^[12]

Douglas W. Hubbard quoted Hanlon's razor and added "a clumsier but more accurate corollary":

Never attribute to malice or stupidity that which can be explained by moderately rational individuals following incentives in a complex system.^[13]

A variation appears in The Wheels of Chance (1896) by H. G. Wells:

There is very little deliberate wickedness in the world. The stupidity of our selfishness gives much the same results indeed, but in the ethical laboratory it shows a different nature.^[14]

A similar quote is also misattributed to Napoleon.^[15] Andrew Roberts, in his biography of Winston Churchill, quotes from Churchill's correspondence with King George VI in February 1943 regarding disagreements with Charles de Gaulle: "His insolence ... may be founded on stupidity rather than malice."^[16]: 771

• Mike Alder § Newton's flaming laser sword
• Finagle's law
• Principle of charity
• Sturgeon's law
• List of eponymous laws

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• Hubbard, Douglas W. (2020). The Failure of Risk Management: Why It's Broken and How to Fix It (Second ed.). Hoboken, New Jersey: Wiley. doi:10.1002/9781119521914. ISBN 9781119522034.