#1: Harmony and Discord

Bitcoin experts talk often of consensus, whose meaning is abstract and

hard to pin down. But the word consensus evolved from the Latin word

concentus, "a singing together, harmony,"[1] so let us talk not of

Bitcoin consensus but of Bitcoin harmony.



Harmony is what makes Bitcoin work. Thousands of full nodes each work

independently to verify the transactions they receive are valid,

producing a harmonious agreement about the state of the Bitcoin

ledger without any node operator needing to trust anyone else. It's

similar to a chorus where each member sings the same song at the same

time to produce something far more beautiful than any of them could

produce alone.



The result of Bitcoin harmony is a system where bitcoins are safe not

just from petty thieves (provided you keep your keys secure) but also

from endless inflation, mass or targeted confiscation, or simply the

bureaucratic morass that is the legacy financial system.



Discord



Discord is the enemy of harmony. If, in the great chorus of Bitcoin full

nodes, half the singers decided to suddenly switch tunes, the harmony

would be lost. In its place would be two smaller singing groups who try

to out sing each other (or who may compete through less scrupulous means),

leaving everyone worse off.



This is what a contentious hard fork has the potential to do. Some

people will program their full nodes to sing one song; other people will

program their full nodes to sing a different song. In the cacophony

that results, there will surely be confusion, recriminations, and loss

of confidence.



For this reason, contentious hard forks are to be avoided.



But this doesn't mean we have to sing the same song forever. We have

other options. The first is gathering widespread agreement to change to

a new song---to hard fork the system without giving discord a foothold.



The second way is to add new layers to the existing harmony. A chorus

will often sing accompaniment to an orchestra, and together they can

entertain audiences neither of them could have pleased alone. Soft forks

are the preferred method for adding new features to Bitcoin because they

allow old nodes to continue to sing the same old song (unless they're

miners), while new nodes get to partake in the expanded choices.



Given two forking paths to the same feature, a soft fork is the safer

option because it leaves no room for discord, and no risk that the

essential harmony that underlies Bitcoin's security will be lost.