Consensus = 75%?

[adamstgBit]

what should be the threshold for saying the "miners have reached consensus BIP XXX wins!"

[maokoto]

I think 75% or even a little less, is a good number. People tend to stay the same and see what happens, so a 75% moving to a new initiative indicates an awesome majority (as a great part of the resting 25% would simply follow what majority says).

[Klestin]

75% was chosen to prevent any single large miner from vetoing the change.

[BitProdigy]

75% was chosen to prevent any single large miner from vetoing the change.

This is a good point… though I think I'd feel more comfortable with something a little higher… tough call

[DannyHamilton]

It depends on what your goal is.

A fork can reach consensus with 1% of the combined hash power.  It just needs to be written in such a way as to ignore all blocks created on the opposing fork.

Of course, such a fork won't have very good security, as anyone with a mining farm will be able to attack it.

If the fork has 50% of the combined hash power, then both forks are equally secure and may co-exist for a period of time each with their own consensus.

By requiring something significantly higher than 50%, a fork can make sure that it's competitor can not attack it with hash power, and can avoid most situations where blocks may be orphaned by blocks from the other fork.  Under this scenario, there is a likelihood that the economic power behind the fork overwhelms any resistance to acceptance.  As such, the vast majority of users are likely to abandon the old consensus and join the new one.

[BitProdigy]

75% was chosen to prevent any single large miner from vetoing the change.

In a consensus decision process we would ask why the large miner is blocking the proposal and attempt to address those concerns and perhaps amend the proposal so that all achieve consensus, this is why I think something higher than 75% could likely still be a viable level for consensus. All it does is ensure consensus among the entire community and avoid a split in the community. It also provides higher security for the new fork against attacks.

[Klestin]

In a consensus decision process we would ask why the large miner is blocking the proposal and attempt to address those concerns and perhaps amend the proposal so that all achieve consensus, this is why I think something higher than 75% could likely still be a viable level for consensus. All it does is ensure consensus among the entire community and avoid a split in the community. It also provides higher security for the new fork against attacks.

Consensus with all parties is not always possible.  75% is the highest possible number that doesn't allow a single pool to veto the change.  It's not perfect, but it is reasonable.

It's also the same percentage used for initial rollout rules for the last big fork (BIP 34).  Some were predicting doom and gloom with that one too.  In reality it was so traumatic that we barely even remember it happened.

[BitProdigy]

Consensus with all parties is not always possible.  75% is the highest possible number that doesn't allow a single pool to veto the change.  It's not perfect, but it is reasonable.

It's also the same percentage used for initial rollout rules for the last big fork (BIP 34).  Some were predicting doom and gloom with that one too.  In reality it was so traumatic that we barely even remember it happened.

Good points, I'm okay with 75% if the rest of the community is as well. It just seems there is skepticism with 75%, people seem to indicate it is not enough to trust that it was the right decision. They threaten that if XT achieves 75% they will split bitcoin into two chains to avoid the decision. But maybe their reservations with XT are enough to prevent it from achieving 75% consensus anyway so their fears are unfounded. Perhaps 75% is enough to ensure that the best solution is achieved.

[Quickseller]

What the miners *want* really does not matter. Enough money has been invested in both miners and mining pool infrastructure that the miners are forced to be profit seeking enterprises. The miners will mine on the chain they believe will generate the most profits for them over the long run.

If a specific miner routinely sells Bitcoin on coinbase (for example) and coinbase only accepts non BIP101 coins then the miner will not mine on a BIP101 blockchain because it would be of no value to them. Granted, in this situation a miner who wanted to mine on a BIP101 blockchain could opt to sell their mining revenue at another exchange, however if enough exchanges only accept a specific "type" of Bitcoin then all other potential "types" of Bitcoin will have very little value.

If there is economic consensus of a certain proposal then miners who do not accept that proposal will lose out on mining revenue. With mining being as competitive as it is, miners will not be able to afford to temporarily mine on a blockchain that has no value with the hopes that economic players will switch to their "type" of Bitcoin because of security concerns. 

[unamis76]

I'd say 90%. It's a better guarantee that everyone is happy and on the same boat, or at least accepts the fork.

[knight22]

More than 75% over a very large group of people with diametrical views is unrealistic and outright impossible IMO. It will only ensure that any progresses are blocked.

[BitcoinNewsMagazine]

I think Hearn chose 75% because he knew he would never get 90% approval from miners.

[glub0x]

Why say "consensus" and not "A majority of 75%" or "super majority"?
When you start to count % you get out of the consensus ...

[Meuh6879]

75% : BIP compliant (full open bar like today)
91% : BIP enforced (filter applied ...)

[adamstgBit]

75% : BIP compliant (full open bar like today)
91% : BIP enforced (filter applied ...)

no idea what i'm looking at

[NorrisK]

I think Hearn chose 75% because he knew he would never get 90% approval from miners.

90% is not realistic...

You have to take into account that a lot of people will be too lazy to even get involved in this..

[Lituation]

There's not a consensus even in poll results.

100%   - 3 (13.6%)
98%   - 2 (9.1%)
95%   - 3 (13.6%)
90%   - 3 (13.6%)
80%   - 3 (13.6%)
75%   - 8 (36.4%)
51%   - 0 (0%)

Everybody think different. The only conclusion we can reach here is it should be at least %75.

[BitProdigy]

There's not a consensus even in poll results.

100%   - 3 (13.6%)
98%   - 2 (9.1%)
95%   - 3 (13.6%)
90%   - 3 (13.6%)
80%   - 3 (13.6%)
75%   - 8 (36.4%)
51%   - 0 (0%)

Everybody think different. The only conclusion we can reach here is it should be at least %75.

The problem with this poll is that it is not fluid. I think consensus requires the ability to change one's mind. I voted for 90% originally, but after discussing the reasons people like 75%, I have agreed with some of them, so now I would change my vote to probably 80% but I am not able to.

Consensus requires a fluid voting mechanism in which the votes are not set in stone but can be changed overtime, slowly evolving to a consensus. A poll like this cannot reach consensus.

[iGotSpots]

Well if you ask Gavin, consensus is having one 'dev' agree with you, then making your own fork. First they make the Foundation go broke, now they don't even bother using what it is there for    I can't believe people are actually following this stupid two-man shit lol

[Lauda]

90% is feasible. I'm not sure why many think it is not. 75% is a bit low. It's not hard to get most pools and most important companies on board. If you have 90% of the main players agreeing, it is very likely that the rest will come on board as well (obviously, if they want to keep doing business).
AFAIK BIP100 needs 90% (it has already ~25%) from the miners.