A Consensus is a general or full agreement between members of a group. A consensus can be useful in deciding what's true (e.g, a scientific consensus), or as a criteria in decision making. A False Consensus can happen when someone thinks a position is in consensus when it isn't. one can also claim a consensus falsely to advance their position and make it difficult for others to oppose it. a False Controversy can happen when one mistakes something to not be in consensus when in fact it is. Claiming false controversies is a common way of creating uncertainty and doubt.
Related Pages: Common Knowledge, Disagreement, Modesty, Modesty argument, Aumann agreement, Government (in the context of democracies), Contrarianism
See also:consensus on wikipedia