A parliament without a parliamentarian
Like a parliament, a blockchain is a means by which a group of people collaborates to produce an ordered list of accepted “resolutions” that is deemed authoritative and legitimate by some community it represents. That list of resolutions may cause the construction of alteration of some side-product. Laws passed by Congress create or alter the United States’ legal code. “Blocks” accepted by Bitcoin “miners” change account balances in an implicit ledger of who owns what Bitcoins. But the authoritative source is always an ordered list of accepted resolutions, from which the state of the side products may mechanically be derived.
.. Most obviously, the leadership of a deliberative assembly may be capable of preventing consideration of resolutions that the membership would pass if required to vote on the question. Anyone who follows real-world politics understands that it matters very much who “controls” a legislative house.
.. Among blockchain enthusiasts, preventing the consideration of a potentially acceptable resolution is usually referred to as a “censorship attack”.
.. Every few minutes, or even seconds, the winner of a new lottery is announced. The winner gets to submit resolutions for consideration by the parliament, and is financially rewarded if her “block” of resolutions is accepted by the majority. The proposal of resolutions is not restricted to miners. They may be submitted by, well, anyone at all. Miners check the resolutions and decide if they are likely to pass. They combine the ones that do seem likely to pass into a “block”, and hope to win the lottery. A miner may try to exclude resolutions that are likely to pass but that she herself disagrees with, but that sort of censorship is unlikely to have any effect, since she is unlikely to win the lottery in any particular round.
.. Blockchains reward consensus: It is lucrative to go along with most others would go along with. Understanding the will of the majority of their colleagues and bending to it is the job of each and every legislator.
.. If more than half of the participants in the Bitcoin blockchain suddenly decided that User A was evil and should not, in fact, be permitted to spend her money, then lottery-winners would quickly learn to exclude her resolutions, and that would become a new, communally enforced norm. People in the Bitcoin community who consider a norm like this illegitimate would refer to it as “censorship” or a “51% attack”. But “51% attack” is just another way of describing “majority rules” when you don’t like the decision of the majority.
.. Ones weight in the parliament is determined by how much computing power one can bring to bear, and, it turns out, sometimes by the form of the computing power, as Bitcoin for example is best run by very specialized chips.
.. A blockchain, like a parliament, is much more a social institution than a technological one, although very clever technology was necessary to design blockchain systems that could become socially credible.