The difference between genius and stupidity is that genius has its limits.
Albert Einstein
All too often, a plot thread depends on one or more characters doing something really stupid. They don't have any chance of doing the smart thing, because then the plot-driving conflicts wouldn't happen.
Even if the stupidity is an organic outgrowth of prior characterization, that doesn't necessarily make it contrivance-free. As addressed in
The Movie and
lampshaded in the "Homer's Enemy" episode of
The Simpsons, the continued tolerance of Homer by his friends, his family, and his employer — indeed, his very
survival — is simply unbelievable at this point.
Contrived stupidity commonly causes things like the collapse of
A Simple Plan in a
Sit Com or the effectiveness of
Schmuck Bait in
Slasher Movies. It is often accompanied by the meta-stupidity of the other characters' ignorance of
Hanlon's Razor. It is vulnerable to
Fridge Logic and may result in a Wall Banger.
Not to be confused with a
Ralph Wiggum, who is just plain dumb, no plot-serving contrivance about it.
Tropes
