> Please explain the difference, in terms of how it should affect my opinion of the person who carries out the act.

Sure.

> A factory boss decides to release some toxic pollutant. They know that it will result in some number of deaths over the next years. They choose to go through with it anyway, because they make more profit than if they disposed of the stuff properly, and that money matters more to them than the lives they’re ending.

This depends a lot on context you haven't provided. Most importantly - is this legal?

If releasing this toxic pollutant is illegal, then they should be prosecuted to the fullest extent of the law. For good reason, that is usually not a death sentence. But if you have an issue with how harsh or not the sentence is, that's a question to take up with the legal system, not with the individual.

Either way, vigilante justice is not needed.

If releasing this pollutant is legal, the question is different. Firstly, why is it legal? If it shouldn't be, then again - this is something to take up with the justice system. Sometimes it's legal for good reasons - it's not clear yet that it is truly toxic. That should definitely inform how we treat someone - releasing something that might be a pollutant is definitely different.

There's just a lot of nuance to this question, it's not an easy soundbite, because the real world is complicated.

> What’s the difference between that and some petty criminal shooting someone in the street so they can take the victim’s wallet?

Let me make a very important point here.

The legality of an action matters a lot more for society than the morality of an action. That's kind of the whole reason we have a legal system, and for good reason! And a pretty fundamental principle of the legal system is that intent matters a whole lot.

Here's some of the differences of the two cases:

- With a criminal shooting someone in the street to take their wallet, I am very scared that he will continue doing this - he will likely shoot more people to get their wallets, because he ignores the laws and morality.

As opposed to the factory boss, who (assuming this is legal), would presumably not do something if it were illegal. So I don't have to worry about his actions - he's not likely to "kill" anyone else if it's against the law.

- A criminal shooting someone is almost certainly trying to kill or at least harm them. The action is very direct. This matters a bunch, because we can be pretty certain of their intent, and therefore how they will act in the future.

As opposed to a factory boss - where the indirectness of the action is far more ambiguous. Did he really know that this would cause deaths? Are there mitigating circumstances (like him being pretty sure it's far enough that it won't cause deaths because it's small amounts, or far from populations)?

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The biggest problem with your examples is that there are really two options here. You either agree with the legal system - in which case, there's a perfect remedy for actions like releasing toxic chemicals, which is using the legal system to prosecute such people.

Or you don't agree with the legal system - you think some things should be illegal, but they aren't.

And this is what is secretly (or not so secretly) motivating most of the pro-vigilante comments. They think that what they consider to be moral is good enough to use to enact justice - they don't need to actually convince their fellow citizens, or convince their lawmakers, to enact their ideas into law. It's enough for them to fervently be sure they are right - that's supposedly a good enough reason to inflict their morality on other people using violence.

And that is a disgusting, anti-democratic worldview, that would leave society in tatters.

Society can't function if everyone can just decide that their morality is the ultimate justice. We have to come together as a society and agree on rules. Because as everyone understands - 99% of people do something that someone else considers wrong.

If our society functioned via "well I'm sure I'm right about what is moral, so I can execute people based on my morality", then pretty soon we'd have total anarchy.

Do you think abortion is murder? Go ahead and kill some doctors. Do you think creating weapons should be illegal? Go ahead and kill the CEO of a weapons manufacturer. Do you think protesting war is terrible because it puts "our soldiers" in danger? Go and shoot up people leading protests. Perhaps you think that climate change will kill us and anyone who works in the car industry is therefore tainted? Go and blow up some car factory workers.

I agree with some of the position above, disagree with some others, as I'm sure most people do. And that's fine! But decent people understand that disagreeing about things, even things that directly pertain to life and death - is not a good enough reason to start killing each other over. We all have to live together, so we all have to work together to agree on what is right or wrong, and to appoint people to collectively enact the will of society - not just have individual citizens run off and do what they want based on their ideas.