We might agree or disagree on both of those points, but we won't have a productive conversation if you can't say what problem you are trying to solve.
As one of the "cognitively different" I think far too literally to have deep discourse with normal human beings in realtime. It takes a long-ish time for me to think through people's written communications to respond appropriately and productively. And sometimes I still get it wrong. I VERY MUCH identify with your above request, but long experience tells me it is unlikely to achieve your desired result.
In many cases the problems others are trying to solve are with the conversations themselves rather than the things the conversations are about. A straightforward plea such as yours to state the problem is generally seen as irrelevant, and a direct answer would possibly be harmful, to actually achieving such goals. Moreover, a direct answer in that case would require more insight into one's own motives than most normal people have.
As with most things involving normal people, it's far easier to be certain than right.
To summarize my position: I see one big problem that need solving:
Supporting lots (millions, eventually billions) of people transacting in Bitcoin.
Ideally at as low a cost as possible, as secure as possible, and in the most decentralized and censorship-resistant way possible.
It is hard to get consensus on HOW to solve that problem, because no solution is obviously lowest cost, most secure, and most decentralized all at the same time, and different people assign different weights to the importance of those three things.
That is an excellent statement of a goal I share and some of the values that a good solution must maximize. I am in agreement with it.
I think that there is sharp divergence of opinions in the community regarding the relationship between censorship-resistance and scaling to millions or billions of transactors. Some seem to assume that absolute censorship-resistance and untraceability are necessary to future growth. Others seem to assume that they would hinder future growth. Some seem to assume that absolute censorship-resistance and untraceability are more important than future growth, and others that they are unimportant relative to future growth.
Some seem to think that Bitcoin has ever had any kind of absolute censorship-resistance and untraceability, but this is a misapprehension. It is 'cash-like' in that if you are very very careful you can acquire and spend it without someone knowing who you are. That is IMO about the greatest degree of censorship-resistance and untraceability that realistically will not result in aggressive prevention of scaling the network by various law enforcement concerns.
I would suggest an attempt to clarify the relationship, but any attempt to do so via open discussion and debate would as some say "generate more heat than light." It might be worth it, but bring hot dogs, marshmallows, and an asbestos suit if you plan to light that fire.
My bias is to "get big fast" -- I think the only way Bitcoin thrives is for lots of people to use it and to be happy using it. If it is a tiny little niche thing then it is much easier for politicians or banks to smother it, paint it as "criminal money", etc. They probably can't kill it, but they sure could make life miserable enough to slow down adoption by a decade or three.
They most assuredly can kill it, for all practical purposes. They can make it illegal to be a Bitcoin-accepting merchant, prosecute unlicensed money transmitters dealing in Bitcoin and deny licenses to any money transmitters who plan to start. That would be an effectively fatal blow. Network effects and immediate mass dumping by the 'get-rich-quick' speculators would do the rest. We could be back to that ten-thousand-bitcoin pizza within a few months if the IMF and a few nations signatory to global anti-money-laundering treaties decide to ban it.
As you point out, our most effective strategy is to get big enough, fast enough, to disincentivize the delivery of that fatal blow. Bitcoin needs to be a system that makes significant contribution to the economy - or at least one whose extinction would cost elected creatures substantial numbers of votes - before it can be seen as 'too big to fail.'
The simplest path to "get big fast" is allowing the chain to grow. All the other solutions take longer or compromise decentralization (e.g. off-chain transactions require one or more semi-trusted entities to validate those off-chain transactions). I'm listening very carefully to anybody who argues that a bigger chain will compromise security, and those concerns are why I am NOT proposing an infinite maximum block size.
Allowing larger block sizes is necessary.
In the future, there will be need for more than 1MB of tx per block. When that happens, our choices are two: have a larger block size, or fail. As blocks grow larger, the costs in bandwidth of running a full node become higher so there will be fewer full nodes. That's bad for security, but unrelated to the block size
limit as such.
Blocks will become larger, no matter which limit is in place above them, at the rate transactions grow. The bandwidth costs of running a full node scale with the number of transactions, not with the limit on the number of transactions. So full nodes will drop out as actual transactions scale up, not as the limit is raised. The security question relevant to the higher block size limit then is whether it is better for security to fail or succeed when more than 1MB of tx per block are needed. I say it is better for security to succeed.
Visa seems to get along fine with a peak tx volume that's about 12 times their average tx volume. That seems like a reasonable margin to me, both for peak traffic and for sudden growth within a retargeting period, while remaining low enough to limit any DoS attack that could be executed via large block size. So I would suggest a block size limit set once every 2016 blocks at the same time as difficulty retargeting, at 12 times the average for the previous 2016 blocks.
My main concern with the proposal this conversation started with (20MB and %40/year) is that adoption of a new technology, if and when it happens, is not that gradual. This is another reason I advocate a plan capable of growing by up to a factor of 12 in successive 2-week periods; if this happens, the timing will surprise all of us and the speed with which the change happens and the size to which it grows will surprise almost all of us.
That scenario is also why I think that just scaling up the blocks is not adequate. Bigger blocks would get us through a crisis, but security depends on every user having a manageable set of data that allows them to independently verify transaction validity, and a block chain that grows linearly relative to a userbase that grows exponentially does not make a manageable set of data. So, IMO, the most important scalability/security job after block size is not side chains - it is blockchain pruning.
