In explaining any human shortcoming, the first tool I reach for is Hanlon’s Razor: Never attribute to malice that which is adequately explained by stupidity.
Steven Pinker, The Sense of Style: The Thinking Person's Guide to Writing in the 21st Century (New York: Viking, 2014), ch. 3. In an endnote, Pinker adds: "Named after Robert J. Hanlon, who contributed it to Arthur Bloch’s Murphy’s Law Book Two: More reasons why things go wrong! (Los Angeles: Price/Stern/Sloan, 1980)."