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Bitcoin solved it with a distributed, massively replicated yet ultimately centralized database. There is only one blockchain, consensus driven, and if you're di

Bitcoin solved it with a distributed, massively replicated yet ultimately centralized database. There is only one blockchain, consensus driven, and if you're disconnected from the blockchain you can't participate. Truly decentralized systems are like BitTorrent or git. There's no singular BitTorrent source, no single server for git. Anyone with a git repo can push/fork/share to their heart's content, even offline, even with other people on isolated networks.

davidgerard 10y ago
And furthermore, the Bitcoin blockchain has rapidly recentralised, because mining benefits from economies of scale, which is a centralising force.
erikb 10y ago
Yeah, bitcoin basically lifted the solution to "one centralized cloud" instead of one centralized server.
c0achmcguirk 10y ago
I suppose you could argue that, but it's just semantics. In the Byzantine Generals Problem the generals are trying to achieve consensus. Their messages to each other need to be stored in a cohesive form, like a log file. The very definition of the Byzantine Generals Problem requires a single truth center. Call it a centralized database if you will, but the problem needs a single source of truth. When independently acting miners or mining pools that do not require a centralized host or server to "bless" their contributions to the single source of truth is indeed a decentralized system. Git and BitTorrent are decentralized too, but they don't have a single source of truth. I may have 100 git repo servers but which copy is the truth? Is Github's copy of master the ONE TRUE master or Bitbucket? Or is it my local repo? In source control it all works out in the end. The developers come to a consensus of where they will push their work. The maintainer will deploy code to production from one of the many repositories. But when you're dealing with financial transactions you definitely need to have a single source of truth. It doesn't mean it isn't decentralized to have a single source of truth.
- astrodust 10y ago
  The single truth center is the blockchain. Without that you have nothing. Git and BitTorrent may not have a single truth center, but they are decentralized and can operate autonomously. Bitcoin cannot. I'd argue it doesn't really solve the generals problem, it just provides a mechanism that can solve it by narrowing the problem down and ignoring some of the ugly edge cases. A true solution to that problem would work in "offline" mode, that is you don't need a persistent link to some authority to ensure you're working with correct information.

davidgerard 10y ago

And furthermore, the Bitcoin blockchain has rapidly recentralised, because mining benefits from economies of scale, which is a centralising force.

erikb 10y ago

Yeah, bitcoin basically lifted the solution to "one centralized cloud" instead of one centralized server.

c0achmcguirk 10y ago

I suppose you could argue that, but it's just semantics. In the Byzantine Generals Problem the generals are trying to achieve consensus. Their messages to each other need to be stored in a cohesive form, like a log file. The very definition of the Byzantine Generals Problem requires a single truth center. Call it a centralized database if you will, but the problem needs a single source of truth. When independently acting miners or mining pools that do not require a centralized host or server to "bless" their contributions to the single source of truth is indeed a decentralized system. Git and BitTorrent are decentralized too, but they don't have a single source of truth. I may have 100 git repo servers but which copy is the truth? Is Github's copy of master the ONE TRUE master or Bitbucket? Or is it my local repo? In source control it all works out in the end. The developers come to a consensus of where they will push their work. The maintainer will deploy code to production from one of the many repositories. But when you're dealing with financial transactions you definitely need to have a single source of truth. It doesn't mean it isn't decentralized to have a single source of truth.

astrodust 10y ago
The single truth center is the blockchain. Without that you have nothing. Git and BitTorrent may not have a single truth center, but they are decentralized and can operate autonomously. Bitcoin cannot. I'd argue it doesn't really solve the generals problem, it just provides a mechanism that can solve it by narrowing the problem down and ignoring some of the ugly edge cases. A true solution to that problem would work in "offline" mode, that is you don't need a persistent link to some authority to ensure you're working with correct information.