When two people have resorted to violence, there's no telling what state of mind they're in, but you can bet it's not a stable one. Everyone should be an active bystander at all times and look out for their neighbors, but when it comes to a physical altercation, there are ways you can help that do not involve becoming physical yourself.
You don't know the context behind the fight or what each party is willing to sacrifice in order to win. You also don't know if either party is armed. For one man in New York, interfering in the madness earned him a stab wound.
It's chaos when a fight breaks out. If you're in an enclosed space, like a bar or a subway car, the fight runs a high risk of injuring other people. If you can help prevent collateral damage, you have a moral obligation to step in and put an end to the madness.
There are a number of ways to help stop a fight without getting physical yourself. By getting in between two aggressors, you run a high risk of escalating a fight to a brawl. Instead, the ever-trusty WikiHow advises either calling the police or enlisting another onlooker for help. Protecting yourself should be the top priority:
Get help from another onlooker. If there is anyone else within hearing range, get them to help you break up the fight before attempting to do it yourself. In situations like this, onlookers don't generally stop to help unless you tell them specifically.
Esquire dissents and provides readers with a step-by-step guide on how to break up a bar fight:
Step 1: If two drinkers start arguing or shoving each other, stand directly between them. If you must, push them apart but don't restrain. That only leads to calls to "hold me back," and that doesn't help anything. Step 2: Identify the more aggressive patron and direct your attention to him. Shift his focus from the other would-be fighter to yourself, even if you're not quite as big as I am. Phrases like "Take it easy" and "It's not worth it" often do trick. Step 3: Have someone remove the less aggressive patron while you're talking. Once he's out of sight, the fight will be over before it even started.