As the community size becomes large the probability of a unanimous decision becomes infinitesimal and the ability of one member to block a decision becomes a target for disruption.
That's very true, which is why it seems silly to call it a 'consensus' rather than a super majority. There should be official policy somewhere outlining exactly what percentage of votes is needed to pass a given thing (e.g. "four-fifths majority is required to appoint an admin").
For many of our votes in the community, Wikipedia uses a two stage near-consensus process which is highly effective. For example, VFD: Members of the community state both their 'vote' and their position and have an ability to discuss their votes and change their votes in an open environment that is free of true coercion.
What about cases where people are being recruited to vote on something like that? I've seen at least one VfD where people were recruited from another source of like-minded people to skew the vote. I'm not sure there is something that can be done about that without potential for abuse, but it's a shady thing to do.
Once the vote is complete, a trusted and experienced member of the community studies the votes and looks for a highly substantial majority one way or another, attempts to exclude votes which were probably made in bad faith or are really voting about something unrelated to the issue. If this person fails to find a clear consensus they take the action which is the least harming and most reversible.
So a simple majority on VfD is not enough? As I explained above, there's a problem with POV pushers grouping together and recruiting to vote. The problem is that often POV pushers are willing to put more effort into getting their way than the non-POV pushers, thus while you will get disinterested "third party" votes, they can easily become overwhelmed since your average person doesn't care as much to vote as your POV pusher does.
---------------------------------------------- Nathan J. Yoder http://www.gummibears.nu/ http://www.gummibears.nu/files/njyoder_pgp.key ----------------------------------------------