On Wed, Dec 16, 2015 at 9:11 PM, Pieter Wuille via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wrote:

We are not avoiding a choice. We don't have the authority to make a choice.

Bitcoin is kind of like a republic where there is separation of powers between various groups.

The power blocs in the process include

- Core Devs

- Miners

- Exchanges

- Merchants

- Customers

Complete agreement is not required for a change.  If merchants and their customers were to switch to different software, then there is little any of the other groups could do.

Consensus is nice, certainly, and it is a good social norm to seek widespread agreement before committing to a decision above objection.  Committing to no block increase is also committing to a decision against objections.

Having said that, each of the groups are not equal in power and organisation.

Merchants and their customers have potentially a large amount of power, but they are disorganised.  There is little way for them to formally express a view, much less put their power behind making a change.  Their potential power is crippled by public action problems.

On the other extreme is the core devs. Their power is based on legitimacy due to having a line of succession starting with Satoshi and respect gained due to technical and political competence.  Being a small group, they are organised and they are also more directly involved.

The miners are less centralised, but statements supported by the majority of the hashing power are regularly made.  The miners' position is that they want dev consensus.  This means that they have delegated their decision making to the core devs. 

The means that the two most powerful groups in Bitcoin have given the core devs the authority to make the decision.  They don't have carte blanche from the miners.

If the core devs made the 2MB hard-fork with a 75% miner threshold, it is highly likely that the other groups would accept it.

That is the only authority that exists in Bitcoin.  The check is that if the authority is abused, the other groups can simply leave (or use checkpointing)