[drdaeman]

> If a blockchain has rules that don't meet my needs, I can choose a different blockchain.

Had this happened with Bitcoin? I think I heard there are some quite major disagreements (something about block sizes and stuff) and there are a lot of users that aren't happy. I don't remember hearing them just "well, whatever" and forking off.

[natrius]

Bitcoin is a special case because it's only really intended to be used as a ledger for bitcoins. Currencies are a collective delusion: they're valuable because other people think they are valuable. Any dispute over what the source of truth is for a currency's ledger strains that delusion, possibly to the breaking point. The value of the currency would suffer, which would defeat the purpose of a fork.

Ethereum is a general purpose blockchain. Forking it could hurt the value of ether, but for many applications, the value of ether doesn't matter. Moving a blockchain-based Twitter from one fork to another is relatively easy and consequence-free.

[tome]

> Currencies are a collective delusion: they're valuable because other people think they are valuable.

This is not true of most currencies. Most currencies are valuable because governments force you to pay them on threat of imprisonment. Bitcoin does not have this feature and therefore, yes, it's hard to see what its fundamental value is.

[drdaeman]

> Moving a blockchain-based Twitter from one fork to another is relatively easy and consequence-free.

I'm not sure it's really consequence-free. It's essentially a netsplit, where the forking party lose connectivity with everyone who's left. Consider the case where Twitter (the centralized one) is suddenly falling apart over some issue into two distinct non-interoperating services. Technically - sure - it's a no-brainer, but socially it feels quite complicated to me.

(I guess, this would work if the app would be designed to use multiple blockchains. I need to give it some thought.)

[natrius]

You got it. Push a new client that supports both chains to users with enough time before the switch for people to upgrade.

[shiro]

Technical curiosity---if I use such a client, and two block chains disagree (on, say, some history that affects the current operation), then won't I end up choosing and sticking one?

[natrius]

Yep! At that point, the problem isn't a blockchain-specific one, it's a more general problem of reconciling conflicting truths. A common, trivial solution is to rank sources of truth.

[jflatow]

What's the benefit of being 'completely decentralized', if the individual joining the network still needs to decide which network and set of rules to trust? Answer: none, you've just pushed the question of trust / centralization to that of choosing the particular fork you want to use.