Hanlon's razor is an adage or rule of thumb that states, "Never attribute to malice that which is adequately explained by stupidity." Known in several other forms, it is a philosophical razor that suggests a way of eliminating unlikely explanations for human behavior. It is probably named after Robert J. Hanlon, who submitted the statement to Murphy's Law Book Two (1980). Similar statements have been recorded since at least the 18th century.

Origin
A similar quotation appears in Robert A. Heinlein's novella Logic of Empire (1941). The character "Doc" in Heinlein's story described the "devil theory" fallacy, explaining, "You have attributed conditions to villainy that simply result from stupidity."

The quotation as such was a submission credited in print to Robert J. Hanlon of Scranton, Pennsylvania, for a compilation of various jokes related to Murphy's law that were published in Arthur Bloch's Murphy's Law Book Two: More Reasons Why Things Go Wrong! (1980). It is unknown whether Hanlon knew of Heinlein's story or whether he independently constructed the phrase.Hanlon's razor became well-known after its inclusion in the Jargon File, a glossary of computer programmer slang, since 1990. 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, though this was possibly intended as a reference to William James Laidlay. 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". 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. Subsequently, in 2002, the Jargon File entry noted the same. Current Jargon File refers to it as a "Murphyism".

The name was inspired by Occam's razor.
Given a reference text about Hanlon's razor, when did the adage become well-known?
Hanlon's razor became well-known after its inclusion in the Jargon File, a glossary of computer programmer slang, since 1990.