[My comments in italic square brackets]
Three Types of Decentralization
When people talk about software decentralization, there are actually three separate axes of centralization/decentralization that they may be talking about. While in some cases it is difficult to see how you can have one without the other, in general, they are quite independent of each other. The axes are as follows:
- Architectural (de)centralization — how many physical computers is a system made up of? How many of those computers can it tolerate breaking down at any single time?
- Political (de)centralization — how many individuals or organizations ultimately control the computers that the system is made up of?
- Logical (de)centralization— does the interface and data structures that the system presents and maintains look more like a single monolithic object, or an amorphous swarm? One simple heuristic is: if you cut the system in half, including both providers and users, will both halves continue to fully operate as independent units?
We can try to put these three dimensions into a chart:
Note that a lot of these placements are very rough and highly debatable. But let’s try going through any of them:
- Traditional corporations are politically centralized (one CEO), architecturally centralized (one head office) and logically centralized (can’t really split them in half)
- Civil law relies on a centralized law-making body, whereas common law is built up of precedent made by many individual judges. Civil law still has some architectural decentralization as there are many courts that nevertheless have large discretion, but common law has more of it. Both are logically centralized (“the law is the law”).
[Note that a network of Biblical courts would operate on similar principles, just with a far smaller scope. First, no positive law — a Christian government has no executive function, and can only ban things, not compel you to do something — and second, no creation of new law: the law today is the same as the law yesterday, and the law today is the same as the law tomorrow.
There remains only one Lawgiver and one King: so there is ethical centralization in this way. The various political systems and nations should be as small and numerous as possible. Finally, the ‘government’ isn’t only the magistrate: the family, the church, and the individual are also legitimate sovereign forces, with only one overall Sovereign, God. It is forbidden for the state to cross into family lines, or for the church to take control of what are fundamentally individual matters.- AP]
- Languages are logically decentralized; the English spoken between Alice and Bob and the English spoken between Charlie and David do not need to agree at all. There is no centralized infrastructure required for a language to exist, and the rules of English grammar are not created or controlled by any one single person (whereas Esperanto was originally invented by Ludwig Zamenhof, though now it functions more like a living language that evolves incrementally with no authority)
- BitTorrent is logically decentralized similarly to how English is. Content delivery networks are similar, but are controlled by one single company.
- Blockchains are politically decentralized (no one controls them) and architecturally decentralized (no infrastructural central point of failure) but they are logically centralized (there is one commonly agreed state and the system behaves like a single computer)
Many times when people talk about the virtues of a blockchain, they describe the convenience benefits of having “one central database”; that centralization is logical centralization, and it’s a kind of centralization that is arguably in many cases good…
Architectural centralization often leads to political centralization, though not necessarily — in a formal democracy, politicians meet and hold votes in some physical governance chamber, but the maintainers of this chamber do not end up deriving any substantial amount of power over decision-making as a result. In computerized systems, architectural but not political decentralization might happen if there is an online community which uses a centralized forum for convenience, but where there is a widely agreed social contract that if the owners of the forum act maliciously then everyone will move to a different forum (communities that are formed around rebellion against what they see as censorship in another forum likely have this property in practice).
Logical centralization makes architectural decentralization harder, but not impossible — see how decentralized consensus networks have already been proven to work, but are more difficult than maintaining BitTorrent. And logical centralization makes political decentralization harder — in logically centralized systems, it’s harder to resolve contention by simply agreeing to “live and let live”.
[PS: The American idea of “Let’s make a deal!” and “Live and let live” — strongly propagated by Gary North — are going to become very powerful globally on the macro scale, as time goes on: regardless of what various socialists, totalitarians, or democrats wish. It looks like Christian libertarian-leaning theonomic small-r republicans have got the winning idea!
Too bad for the centralizing Secularist, Marxist, and Islamic alternatives. Not many tears streaming from my eyes, though, I must admit.]
The next question is, why is decentralization useful in the first place? There are generally several arguments raised:
- Fault tolerance — decentralized systems are less likely to fail accidentally because they rely on many separate components that are not likely to fail.
- Attack resistance — decentralized systems are more expensive to attack and destroy or manipulate because they lack sensitive central points that can be attacked at much lower cost than the economic size of the surrounding system.
- Collusion resistance — it is much harder for participants in decentralized systems to collude to act in ways that benefit them at the expense of other participants, whereas the leaderships of corporations and governments collude in ways that benefit themselves but harm less well-coordinated citizens, customers, employees and the general public all the time.
All three arguments are important and valid, but all three arguments lead to some interesting and different conclusions once you start thinking about protocol decisions with the three individual perspectives in mind. Let us try to expand out each of these arguments one by one.
[And this is where I will stop, and recommend that you read the complete article yourself!]