[PeterisP]

There is no such thing consensus of the people in any communities of nontrivial size.

In anarchy situations, whoever is capable of filling the power vacuum creates new rules - the "highly motivated and well armed" groups don't break the rules (since if they disagree, there's obviously not a consensus about those rules); they define the rules and others possibly break them.

[AnimalMuppet]

True enough. But, technically, once someone fills the power vacuum, it's not anarchy any longer.

(But if you're living in it, that "technically" isn't going to comfort you one bit...)