Hanlon's razor
About
Hanlon's razor is an expression of the idea that stupidity or incompetence are more likely than malice, i.e. that one shouldn't leap to assume malicious intent. The canonical phrasing appears to be:
Never attribute to malice that which is adequately explained by stupidity.
It is often seen as a special case of Occam's razor, which implies that explaining an act as malice requires more assumptions than does explaining it as stupidity, but this is not necessarily the case. For example: who is more likely to acquire political or economic power – someone who is stupid, or someone who is maliciously selfish?
Caveat
Hanlon's razor may result in excusing instances of advanced malice as mere stupidity, because sufficiently advanced incompetence is indistinguishable from malice.