n. A principle, used most often in computing circles, that says "Never attribute to malice that which can be adequately explained by stupidity."
2001
But faulty forecasts, here in Ireland anyway, are never, ever due to Murphy's Law or human error. Neither does Hanlon's Razor hold the key.
1984 (earliest)
Competence. I am reminded of an extension to Murphy's Law, cryptically named Hanlon's Razor: "Never attribute to malice that which is adequately explained by stupidity."
The razor part of Hanlon's Razor is derived from the famous Occam's Razor, which is the principle of reducing assumptions to their absolute minimum (as Albert Einstein once said: "Things should be a simple as possible, but no simpler"). The Hanlon part is more problematic, and no one is sure who this person is. The best guess I've seen is that it's a corruption (through either malice or stupidity, one supposes) of Heinlein, since the noted science fiction writer Robert A. Heinlein used the phrase "You have attributed conditions to villainy that simply result from stupidity" in his 1941 story "Logic of Empire."