Think Incompetence before Malice

Infinite sources (too obvious perhaps.  I bet there is a patent on this).
Wikipedia sez.

The quotation first came from Robert J. Hanlon of Scranton, Pennsylvania, according to his friend Joseph Bigler, as a submission for a book compilation of various jokes related to Murphy's lawpublished in 1980 titled Murphy's Law Book Two, More Reasons Why Things Go Wrong.^[1] The name was inspired by Occam's razor.^[2]

A similar quotation appears in Robert A. Heinlein's 1941 short story "Logic of Empire" ("You have attributed conditions to villainy that simply result from stupidity"); this was noticed in 1996 (five years before Bigler identified the Robert J. Hanlon citation) and first referenced in version 4.0.0 of the Jargon File,^[3] with speculation that Hanlon's Razor might be a corruption of "Heinlein's Razor". "Heinlein's Razor" has since been defined as variations on Never attribute to malice that which can be adequately explained by stupidity, but don't rule out malice.^[4] Yet another similarepigram ("Never ascribe to malice that which is adequately explained by incompetence") has been widely attributed to Napoleon Bonaparte.^[5] Another similar quote appears in Goethe's The Sorrows of Young Werther (1774): "...misunderstandings and neglect create more confusion in this world than trickery and malice. At any rate, the last two are certainly much less frequent."

A common (and more laconic) British English variation, coined by Sir Bernard Ingham, is the saying "cock-up before conspiracy", deriving from this quotation:

Many journalists have fallen for the conspiracy theory of government. I do assure you that they would produce more accurate work if they adhered to the cock-up theory.

—Sir Bernard Ingham^[6]