In an on-line world it would be much easier to enforce banishment or selective ostracism than in real life. Filtering agents could look for certificates from accepted enforcement agencies before letting messages through. Each user could have a set of agencies which were compatible with his principles, and another set of "outlaws". You could even end up with the effect of multiple "logical subnets" of people who communicate with each other but not outside their subnet. Some nets might respect intellectual property, others not, and so on.
Yeah I've been thinking about this alot. It seems that my system has a high probability of increasing cultural fragmentation. I have occasionally tried to support the thesis that as the level of technology sophistication increases, the fraction of the population that is employed in "artistic" professions [jobs that create things, the purpose of which is our intellectual stimulation] will increase and further that the number of artistic jobs that can be supported by a population has a positive correlation with the population's degree of cultural fragmentation. Perhaps there are some _positive_ economic benefits to the creation of seperate "subnets", and the cryptographic walls erected by cyberspatial governments will be the mechanism by which this fragmentation occurs. JWS