You’re walking down the street and you see a boy laying down on the sidewalk. He looks like he’s freezing, maybe you should do something. You look around. In front of you, a few people have just walked past and ignored him.
He looks like he could use some help, and you want to help him. But all those other people just ignored him, so you begin to doubt yourself. Should you really help? Does he even need help? If he did then why didn’t anyone else do anything?
You think “No one else did anything, therefore there is nothing to be done.”
And as you walk past him, the person a few footsteps behind you pauses briefly to process the situation. Their initial instinct tells them that they should help, but thankfully you’ve provided clear evidence that the boy doesn’t need help. If he did, why would you ignore him?