You say Hanlon, I say Heinlein

Hanlon's Razor 

(possibly a corruption of "Heinlein's Razor") 

defined as variations on:

"Never attribute to malice that which can be 

adequately explained by stupidity,

but don't rule out malice."

----------- ALSO  -----------

 There is always one more imbecile than you counted on
and 
Artificial intelligence is no match for natural stupidity.