So consider the situation where you did something bad like killing someone (or something less serious) which means that you now have bad karma. So now something bad needs to happen to you, considering all things this thing will statistically caused by another person doing something to hurt you (physically or mentally) which adds to their bad karma and so on.
My question is what would have to be done to stop this chain reaction?
Your bad Karma does not cause bad Karma for others. If another person gets a mindset to kill, it's not a result of your bad Karma. It's a result of his own aversion and volition. But your bad karma can place you at the wrong place at the wrong time.
ex: A crocodile might attack anyone who gets into the water. Your bad karma can place you at the river when the crocodile is waiting to grab a meal. Coconuts fall down from coconut trees whether you killed someone or not. But your bad Karma can place you under a coconut tree when a coconut is falling down.
It's not that the first offender's karma causes the second offender's karma. Instead, as my first teacher explained, in context of the victim-and-offender relationship karma works as a giant matchmaking machine, bringing the two together to rip the fruits of the seeds once sawn.
But you are right in that the mutual evil deeds don't cancel themselves out. Instead, karma has self-sustaining inertia, like a heavy spinning wheel - the more you spin it the more it spins you.
However, as Buddha has shown, not all of the future is determined solely by past karma. Our decision-making NOW is the most important factor.
In your example, both people, the original offender and the second offender, would commit their crimes due to 1) their own bad karma, PLUS 2) their own bad decision-making on the spot.
So "to stop the chain reaction", the only thing we can control is ourselves:
"Am I choosing to act out my previous pain, insults and injuries -- and by doing thus to spin the wheel of evil? Or should the chain of evil stop on myself? Let me spin the wheel of love and compassion instead!"
I'm a cafeteria Buddhist, blending what I understand of it with what I understand of behavioral science and physics. Karma literally translates as "action."
Newton's third law: for ever action, there is an equal and opposite reaction. So for a good action, there is a generally equal in magnitude good action coming back to you. For a bad action, likewise. These actions aren't necessarily for another day... or lifetime... to come. Actions could be immediate, in the way a waiter treats you, someone responds to a post or comment, you are apprehended by the law, and so on.
Good actions beget good, and the more you do, the more you tend to be the recipient of good action. The good energy this produces within you and around you is a virtuous cycle with many benefits for health and well being. Bad actions beget bad. The world is very much a mirror for who you are being.
I see karma as a way of understanding the interaction of all the phenomena surrounding us and a guidepost for happiness and peace.
Lord Buddha said this about your scenario...
"Enmity against enmity can't win"
Karma can be a chain reaction occasionally.If i kill you and you die with anger against me it will create a chain reaction.But if you die with "Metta/Maithree" (a form of unshakable kindness explained in Buddhism) in your mind towards me it will not create a chain reaction.But i will have bad karma.
So your question is, "when it comes to effect me wouldn't someone else come to kill me and wouldn't that person gain bad karma?"
The answer is no, because that is not the only way a karma can come to effect someone.
Imagine i killed you with a gun. So what happened, I sent something through you. Now memorize all the horror movie moments you've had and tell me how many ways are there for a person to die by having something go through his body!
As you can see there is no need for an additional individual for karma to take effect.
Now let's see the same with another individual in the equation. I have killed you and now i have enough karma to be murdered.And i am no angel,i have many enemies with "small beefs" (quarrel/enmity) against me. Now as my karma has changed if they try to hurt me there is a huge potential of something going wrong and me dying in the process.They would even be more compelled to kill me.What is important here is that no matter what they still have their heads too.They can choose to not to do anything.But if they try to hurt me i could die even if they have no plans for my death.
I must tell you what lord Buddha said about trying to learn how karma works. Lord Buddha said only a Lord Buddha can tell the true effect of a karma and no one else is equally accurate in that task.This statement was proved many times by "Arahants" who asked about some people's next lives.
Kamma is complicated subject which only a Buddha fully understands. Kamma influences your environment to create the experience for you. Say you were assaulted. This can be due to Karma and sometime not. Also the person could have become irritated because of you bad Kamma and hit you. Some other cases stimuli can be from other source and you bad Kamma put you there.
In cases where you bad Kamma simulates action of others this can be cumulative as you said where someone gets bad Kamma to which he might have to real a result which intern cases someone else to get bad Kamma. But again not all kamma give result. Also some results are not though volitional action (accidents, post collapsing) of others hence no one makes kamma when they bear fruit.
In most cases kamma tent to bear fruit though people we meet regularly and the environment you are mostly in. Hence generally most cases bad kamma cumulates. This is most evident there are times when life span increases as well as decreases which is based on the cumulative Kamma of the inhabitants of the particular plane.
If you kill so.eone let's say the bad karma or result will be sickness injury or short life all of those things can be occur without injury to another person and injury isn't a cause of more suffering neither is death the Buddha teaching pain is inevitable suffering is optional, make sure you get rid of suffering before and after the unwholesome karma
