See Cass R. Sunstein - Why Societies Need Dissent<ref>[http://papers.ssrn.com/sol3/papers.cfm?abstract_id=441340 Sunstein, Cass R., Why Societies Need Dissent. Harvard University Press, September 2003]</ref>, and slso this articla article that suggest that that social netwoerks networks will create increase in group polarization<ref>[http://arxiv.org/pdf/physics/0603023.pdf Petter Holme and M. E. J. Newman, Nonequilibrium phase transition in the coevolution of networks and opinions, Physical Review E, 2006]</ref>