As a sample, Marcus poses a question worth pondering:
Let's say you're a police officer out watching a parade. You hear a scream to your right, and see that someone has been stabbed. Quickly, you ask the victim if she knows who attacked her, and she says he slipped directly into the procession.
1. Is your first reaction to start spraying bullets in the general direction of the parade?
2. If you do, and you hit a bystander, who gets the blame?