[alistoriv]

And if a hypothetical commune became dominant and an existential threat to the existence of a hypothetical libertarian society? The Communist Party of the Philippines operates as a parallel government in many respects, do you think that should be allowed? The Zapatistas?

It's misleading to say that it would be a-ok to start a socialist society in a libertarian society. It (like many aspects of libertarian analysis, in my opinion) ignores the reality of a political situation like the one described.

[skookumchuck]

It's not misleading. Hundreds (thousands?) of communes have been set up in the US. As far as I know, nobody has tried to shut them down. Nobody is stopping you from joining an existing one. You can find them via Google.

More to the point, the notion that communes are a threat to libertarianism is flat out false. Libertarianism is about freedom to associate with and do business with people as you please. That includes pooling ones' interests in a commune.

What you cannot do under libertarianism is force someone to join, or prevent someone from leaving.