Hanlon's razor

Origin

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), the adage was titled "Hanlon's razor", without any indication of who "Hanlon" might be.

A statement similar to Hanlon's razor appears in Robert A. Heinlein's 1941 novella "Logic of Empire". The character Doc in the story describes the "devil theory" fallacy, explaining, "You have attributed conditions to villainy that simply result from stupidity." English science fiction author H. G. Wells used a similar phrase in a letter published in the March 1898 edition of The Critic, where he spoke of Fighters From Mars, an unauthorised adaptation of The War of the Worlds, with the phrase "...not so much downright wickedness as a terrible mistake."

Hanlon's razor became well known after its inclusion in the Jargon File, a glossary of computer programmer slang, in 1990. Later that year, the Jargon File editors declared its origin unknown and wrote that there was a similar epigram by William James. However, this was considered misleading and likely to have actually referred to William James Laidlay, as Laidlay was known to have written a similar statement. In 1996, the Jargon File entry on Hanlon's Razor noted the existence of Laidlay's statement in Heinlein's novella, with speculation that "Hanlon's razor" might be a corruption of "Heinlein's Razor". 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. In 2002, the Jargon File entry noted the same. The Jargon File now calls it a "Murphyism".

The name was inspired by Occam's razor.