A related point. Michael brings up the question of polling and the like. Michael's second and third questions are "Who gets to be part of the polling sample? . . . ." and "How does one actually go about doing the polling to assess consensus? . . . ." But I am not sure that consensus can be easily and necessarily equated with "the majority view". A given consensus emerges over time and is something that is the result of the combined force of monographs by experts, the introductory level text books, websites, the passing comments in conference papers, conversations over a beer etc. I am not being facetious about the importance of the latter -- it is in the casual discussions that one begins to feel the existence of a consensus, or the lack of one. Of course there is some relationship between consensus and majority view -- I cannot imagine a consensus that is not also the majority view -- but consensus is about much more than just a count of heads.