[Entelechy]

we need to define the proper use of the space that welcomes unsolicited cultural messages;

This only becomes an issue of individual rights if we assume that public spaces must be treated as a commons (something I think we both reject). In any other circumstance, there is a landowner (either the govt. or a private individual) and that person or people has control over use of the public space.

Now it may be more civil to conform to the greater community when managing a public space -- but it is not a rights violation to do otherwise.

[annalex]

What I am saying is this: in a fully privatized environment, an entrepreneur will come along and offer a space for unsolicited messaging on his private property, San Marco Square, Inc.. Because there is a market for it, he will strive to allow as much liberty to the messengers as consistent with the individual rights of the messengers and messengees. He doesn't have to do that, but if he doesn't, all the participants will go to his competitor who does. Then, that entrepreneur as well as his competitors will face the same dilemmas the government faces today.