Consensus in a wiki environment/Establishing consensus

What happens on a wiki if 45 percent of people feel one way and 55 percent of people feel another way about some change or implementation on a wiki? What happens if there are only two or three people working on a project or an area of the wiki and those two or three people all disagree? Will the two "out vote" the one? Consensus is not a vote though, is it?

So communication must be key in establishing consensus.

Theoretically, once consensus is established, all stakeholders will agree, that the course of action to be taken is the right course of action to be taken. Everyone should be happy... in theory.

How are past users opinions taken into account? If inactive wiki contributors are not available to voice their opinion, or lack of one, should their investment in the direction of the wiki not be taken into account in deciding and agreeing what exactly is the consensus?

What happens if there are 1000 users, and 999 of those users feel one way, and the other one user feels a different way? Is that consensus? It seems like it might be a consensus among the 999 users, but is it truly then a consensus among all the participants within the wiki?

What about the location of consensus? If a few people create a consensus somewhere else about another project, does that consensus override local consensus?