What does Consensus mean?
In everyday language, “common, general, or widespread agreement”.
Although this term is used everywhere in blockchain and in distributed computing long before that, ironically, there is no general agreement on the precise definition of the word itself.
Its ordinary meaning is intuitive for people who participate actively in a group and know enough about the decision making process to understand what it means in their personal circumstances. They basically understand how consensus was determined, who was for or against it, and what the consequences are as it relates to their families, clubs, or offices.
What Happens When You Don’t Know Everyone?
A decentralized economy includes people who may never know much about each other. In that setting, let’s take another look at consensus. Do we know how to reach consensus as strangers? Does it take a majority? Is there a vote? If there is a vote, then there are rules to determine a process, a threshold, and the implementation of the decision. However, even when all of these are formally specified, it is quite likely a subset of people will not like the outcome and will want to change it. (Take one look at politics.) Consensus can be contentious.
This issue is especially problematic if there are blocks of data determined by consensus, and everyone who uses that blockchain is supposed to accept and agree those data are permanent and immutable.
The Problem of Consensus for Blockchain.
Personal uncertainty, about the acceptability of a consensus outcome, makes it less likely a blockchain built by consensus will be used by parties who wish to coordinate, but distrust each other.
It may seem like all cryptocurrency users are happy to depend on their blockchain consensus mechanisms. Remember, however, they have self-selected. How can we bring the economic value of blockchain technology to everyone?
Used in a Sentence:
For blockchain to be of value, users must agree to agree; consensus between computers is less important than for users to be reassured that the data are a dependable source of neutrally and correctly validated data that all honest users will accept as permanent.
Last Updated: March 21, 2021