[Bitcoin-development] Block Size Increase

Mike Hearn mike at plan99.net
Thu May 7 16:11:11 UTC 2015

> It is an argument against my admittedly vague definition of
> "non-controversial change".

If it's an argument against something you said, it's not a straw man, right

Consensus has to be defined as agreement between a group of people. Who are
those people? If you don't know, it's impossible to decide when there is
consensus or not.

Right now there is this nice warm fuzzy notion that decisions in Bitcoin
Core are made by consensus. "Controversial" changes are avoided. I am
trying to show you that this is just marketing. Nobody can define what
these terms even mean. It would be more accurate to say decisions are
vetoed by whoever shows up and complains enough, regardless of technical
merit. After all, my own getutxo change was merged after a lot of technical
debate (and trolling) ..... then unmerged a day later because "it's a

So if Gavin showed up and complained a lot about side chains or whatever,
what you're saying is, oh that's different. We'd ignore him. But when
someone else complains about a change they don't like, that's OK.

Heck, I could easily come up with a dozen reasons to object to almost any
change, if I felt like it. Would I then be considered not a part of the
consensus because that'd be convenient?

> I'm sure that's not what the proponents of the size increase want, and
> I'm not defending 1 MB as a sacred limit  or anything, but my question
> is "where is the limit for them?"

20mb is an arbitrary number, just like 1mb. It's good enough to keep the
Bitcoin ecosystem operating as it presently does: gentle growth in usage
with the technology that exists and is implemented. Gavin has discussed in
his blog why he chose 20mb, I think. It's the result of some estimates
based on average network/hardware capabilities.

Perhaps one day 20mb will not be enough. Perhaps then the limit will be
raised again, if there is sufficient demand.

You are correct that "no limit at all" is a possible answer. More
precisely, in that case miners would choose. Gavin's original proposal was
20mb+X where X is decided by some incrementing formula over time, chosen to
approximate expected improvements in hardware and software. That was cool
too. The 20mb figure and the formula were an attempt to address the
concerns of people who are worried about the block size increase:  a
meet-in-the-middle compromise.

Unfortunately it's hard to know what other kinds of meet-in-the-middle
compromise could be made here. I'm sure Gavin would consider them if he
knew. But the concerns provided are too vague to address. There are no
numbers in them, for example:

   - We need more research -> how much more?
   - I'm not against changing the size, just not now -> then when?
   - I'm not wedded to 1mb, but not sure 20mb is right -> then what?
   - Full node count is going down -> then what size do you think would fix
   that? 100kb?
   - It will make mining more centralised -> how do you measure that and
   how much centralisation would you accept?

and so on.
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