No Stupid Questions

Historically speaking, in most cases where the state has had loose control the "justice" enforced by populations hasn't been pretty. The idea of decentralized community enforcement is only able to be romanticized because it is distant, and it's distant because it fucking sucks. Lynchings, witch burnings, and especially feuds and unending cycles of retributive violence - although the places they have happened in were not stateless, they primarily happened in areas where state control was loose.

Feuds are the natural consequence of a lack of centralized authority. If a Hatfield goes out and kills someone, then the McCoy's deliver "decentralized community justice" by killing the murderer. Except the Hatfield's say their guy was innocent and the accusation was a pretext, the McCoy's are the real killers, so they go out and deliver "decentralized community justice" by killing a McCoy. And so on and so on for generations until everybody's forgotten what even started it.

The only thing that actually puts a stop to that is the big bad state coming in and saying, "Anytime anyone murders anyone, it is an offense against me. No more "settling the score," the score is settled now because I say it is, and if either of you keep this up you will be charged."

But it's not just the historical examples, which I'm sure "won't count" for whatever reason - the effect is also observable in game theory.

In the case of the "Iterated Prisoner's Delimma," the most effective strategy is "tit for tat," where defection is punished with defection and cooperation is rewarded with cooperation, which tends to result in cooperation with others following the same strategy. But what happens when we expand beyond two players?

For example, a game with a hundred players where everyone can put money in a pot, and the pot is doubled and then redistributed equally to everyone. In this case, it's impossible to do "tit for tat" because punishing defection with defection means defecting against everyone else, who would them try to punish you for defecting, and so on. In this case, the most effective strategy is to contribute nothing, and it's only a matter of time before everyone stops contributing.

This is a basic collective action problem, applicable to many irl situations, and the way to solve it is, again, to have a big bad centralized authority come in and tell everyone they have to contribute to the pot whether they like it or not. "The pot" could mean social services, infrastructure, common defense, etc.

State is not the same thing as government

There would be FAR less terrorism because terrorism is just the violent reaction to injustices perpetrated BY THE STATE by people that feel they’ve been wronged by the state.

Poorly.

Likely a volunteer neighborhood watch, then multiple neighborhood watch from different villages would coordinate and eventually they would probably consolidate to make coordination easier, perhaps some kind of salary, oh wait...

Mass murderers would be handled about the same, ie. taken down by local security after the fact.

Terrorism would be less likely to happen; without an organized state to terrorize, what's the point? There's no one to agree to the terrorists' demands.

I call myself an Anarchist, but I don't think there are many reasonable Anarchists who want a society without any government. It's necessary for the function of protecting people. It shouldn't be involved in telling people how to live their lives where it doesn't effect others though, such as laws against drug use or any other lifestyle choices. It should step in to protect people from exploitation and dangers that they don't choose freely.

To answer your question, it couldn't. Essentially no one is asking for that though, so it's not really a useful question.

It wouldn't.

Stateless societies don't work, that's why despite thousands of years of recorded history, we don't have any record of one ever succeeding.

Even just having a village elder who decides disputes is a form of state. Hell, having parents who decide the rules in a family is a form of state.

By not creating the mass murderers and terrorists in the first place, ideally.

Beyond that, anarchism usually embraces the idea of the broadly armed society and militias.

By sponsoring it.

It wouldn't

How big would said society be

There could be alternative to state with its own police. If alternative to state is some kind of unions/syndicates, it could mean, there are, for example, Team Space (Union of Spaceship Institutions + some relevant Universities and Industry Manufacturers) and Team Earth (Union of Agricultural Manufacturers + Farmers + Union of Solar Energy Organisations) represented in the same city. Each of those have their own police funded by their own taxpayers. There could be many such "teams" in the same city, and they together manage infrastructure and security in the city. I think it's important that those teams are kind of "omnipresent", meaning the same team is present in many locations throughout the planet. For example there could be multiple dozens of such teams, and each city on the planet is run by some combination of those teams, which depends on variety of cultural and economic concerns and interests of such teams.