A few people remain silent and still, a few nod their heads, and maybe one or two exclaim “Yes.” Then the person who wants the decision announces: "We have a consensus!" (After all, "everyone agreed--no one stated any objections.")
Poor implementation and outcomes in such situations are quite likely. High quality consensus requires that each person give explicit indication of being able both to live with the decision and to fully commit to successful implementation—even if not fully satisfied. This occurs only with balanced, fair, and rational discussion in which everyone participates and everyone feels heard. (Chris Mcgoff The Primes, 2012 and Peter Scholtes et al The Team Handbook, 1989)
Poor quality consensus decisions result from lack of a shared definition of consensus, lack of a systematic and clear way for each person to indicate if they are in consensus, and arguments and debates as opposed to assuring all opinions are fully heard. Also, use of traditional definitions like "no one voices objections," "everyone agrees with everything," "everyone is fully satisfied," or "majority rules" are not effective and perhaps even destructive to the best efforts. (McGoff, 2012)
Groups have used a wide variety of methods for each person to specifically indicate if they are in consensus: An example is to use a scale of 1 - 5 with "5" meaning a high level of enthusiasm and "1" meaning no enthusiasm. A cut-off is defined (e.g at a rating of '1" or "2" even from just one person) which means insufficient enthusiasm to commit to implementation. The effort to come to a decision would then stop and dialogue would be restarted. This might lead to revision of the proposed decision or a shift in enthusiasm due to deeper exploration of issues. This iterative process increases the odds of a creative decision and shared motivation for implementation.
High quality consensus decision making is not easy. It requires high quality dialogue so that decisions reflect the thinking of all group members. The skills for moving back and forth between checking for consensus and dialogue require a good deal of intentional practice over time.