Does a method exist where a secret is generated so that is is unknown until 3 or more people (predetermined) reach consensus that it should be revealed?
If I understand the question right, what you are looking for is a fair secret sharing protocol. Most secret sharing protocols are unfair. For example, in 3-out-of-4 secret sharing with 2 dishonest parties, once one honest party broadcasts their share, the two dishonest parties can privately collude to reconstruct the secret. Then if they refuse to participate, the 2 honest parties cannot reconstruct the secret.
Fairness is described as "if there is a player getting the secret in the recovery phase, then each player participating to the reconstruction process does too" . That reference proposes such a protocol and you can find a number of others by looking at the references in that paper.