Reflection on the Bitcoin Block Size War

Recently, I finished reading two main historical books documenting the Bitcoin block size war of the 2010s, representing two opposing viewpoints:

• Jonathan Bier's "The Blocksize War" tells the story from the perspective of supporting small blocks.
• Roger Ver and Steve Patterson's "Hijacking Bitcoin" discusses from the perspective of supporting large Blocks.

Reading these two historical books that document events I personally experienced and participated in is fascinating. Although I am quite familiar with most of the events and the narratives from both sides, there are still some interesting details that I either didn't know or had forgotten, and it's also intriguing to look at these situations with a fresh perspective. At that time, I was a "big block supporter", but a pragmatic moderate block advocate, opposing extreme growth or absolutist statements. So do I still support the views I held back then?

How does the Small Block Faction view the Block Size War?

The block size war initially revolved around a simple question: should Bitcoin increase the block size limit from 1 MB through a hard fork to allow for more transactions, reduce fees, but at the cost of making it more difficult and expensive to run and validate nodes?

The impression I got from Bier's book is that, although the small block faction does care about this specific issue, they are more concerned with how protocol-level issues are determined. In their view, protocol changes (, especially "hard forks" ), should be very rare and require a high level of consensus among protocol users.

Bitcoin does not attempt to compete with payment processors. Instead, Bitcoin seeks to become a completely new type of currency, free from the control of central organizations and central banks. If Bitcoin begins to have a highly active governance structure, or becomes susceptible to manipulation by miners, exchanges, or other large companies, it will forever lose this precious unique advantage.

In Bier's narrative, what causes the most discomfort for the small block faction is that the big block faction often tries to gather a relatively small number of large players to legitimize and promote their preferred changes------this is completely at odds with the small block faction's views on how governance should be conducted.

How do the Big Block proponents view the block size war?

The big block faction usually focuses on a key question: what should Bitcoin really be? Should it be a store of value ------ digital gold, or a means of payment ------ digital cash? For them, it has been clear from the very beginning that the original vision, as well as the vision recognized by all big block supporters, is digital cash. This is even explicitly mentioned in the white paper!

The big block faction often cites two other works by Satoshi Nakamoto:

1. The simplified payment verification section in the white paper discusses how individual users can use Merkle proofs to verify whether their payments are included when the blocks become very large, without needing to verify the entire chain.

2. A statement on Bitcointalk advocating for gradually increasing block size through hard forks.

For them, the shift from focusing on digital cash to digital gold is a turn that is agreed upon by a small and closely-knit core group of developers, who then believe that, having discussed the issue internally and reached a conclusion, they have the right to impose their views on the entire project.

The small block faction indeed proposed that Bitcoin could serve as both cash and gold solutions------that is, Bitcoin becomes the "first layer" focused on being gold, while "second layer" protocols built on Bitcoin, such as the Lightning Network, provide cheap payments without using the blockchain for every transaction. However, these solutions are severely lacking in practice, and Ver has spent several chapters critically analyzing them. For instance, even if everyone switches to the Lightning Network, it will ultimately still require an increase in block size to accommodate hundreds of millions of users. Furthermore, receiving coins trustlessly on the Lightning Network requires having an online node, and to ensure your coins are not stolen, you need to check the chain once a week. These complexities, Ver believes, will inevitably push users to interact with the Lightning Network in a centralized manner.

The Key Differences in Their Views

Ver's description of the specific debate aligns with the small block faction: both sides agree that the small block faction places more emphasis on the ease of running nodes, while the large block faction prioritizes low transaction fees. They both acknowledge that the reasonable differences in beliefs are a key factor leading to the debate.

However, Bier and Ver have completely different descriptions of most deeper issues. For Bier, the small block faction represents users, opposing a small but powerful group of miners and exchanges that attempt to control the blockchain network for their own benefit. Small blocks maintain Bitcoin's decentralization by ensuring that ordinary users can run nodes and verify the blockchain network. For Ver, the large block faction represents users, opposing a small group of self-proclaimed high priests and venture capital-backed companies ( such as Blockstream ), which profit from the second-layer solutions necessary for the small block roadmap. Large blocks maintain Bitcoin's decentralization by ensuring that users can continue to afford on-chain transaction fees without relying on centralized second-layer infrastructure.

I see that the closest point of "consensus on the debate terms" between both sides is Bier's book acknowledging that many large Block advocates are well-intentioned, even admitting their reasonable dissatisfaction with forum moderators who support small Block being blocked from opposing views, but frequently criticizing the incompetence of the large Block advocates. In contrast, Ver's book tends to attribute malicious intent or even conspiracy theories to the small Block advocates, but rarely criticizes their capabilities. This reflects a common political metaphor I've heard in many instances, which is "the right believes the left is naive, and the left believes the right is evil."

How do I view the block size war? How do I see it now?

During my personal experience of the Bitcoin block size war, I usually stood on the side of the big block faction. My support for the big block faction is focused on several key points:

• A key intention of Bitcoin is digital cash, and high transaction fees may kill this use case. Although second-layer protocols can theoretically provide lower fees, the entire concept has not been fully tested. It is very irresponsible for the small block faction to insist on the small block roadmap while knowing very little about the actual effects of the Lightning Network. Today, real-world experiences with the Lightning Network have made pessimistic views more prevalent.

• I am not convinced by the "meta-level (" assertion from the small block faction. The small block faction often claims that "Bitcoin should be controlled by users" and that "users do not support large blocks," yet they have never been willing to clearly define who "users" are or how to measure users' willingness. The large block faction implicitly proposes at least three different methods of calculating users: hash power, public statements from well-known companies, and discussions on social media, while the small block faction denies each of these methods. The large block faction did not organize the New York Agreement out of a fondness for "groups," but rather because the small block faction insists that any controversial changes require consensus among "users," and signing statements from major stakeholders is considered by the large block faction to be the only practically feasible method.

• Segregated Witness is a proposal adopted by the small block faction that slightly increases the block size, which seems unnecessarily complex compared to simply hard forking to increase the block size. The small block faction ultimately formed the doctrine of "soft forks are good, hard forks are bad" ), which I strongly oppose (, and designed their block size increase plan to fit this rule, although Bier acknowledged that this brought serious complexity, to the point that many large block advocates could not understand the proposal. I believe the small block faction is not just "cautious"; they are making arbitrary choices between different types of caution, opting for one ) without hard forks ( at the expense of another ) maintaining the simplicity and clarity of the code and specifications (, because it aligns with their agenda. Ultimately, the large block faction also abandoned "simplicity and clarity" and turned to ideas like adaptive block size increases as seen in Bitcoin Unlimited, which Bier ) understandably ( criticized harshly.

• The small block faction is indeed conducting very uncool social media censorship to impose their views, ultimately leading to That infamous quote from Theymos: "If 90% of /r/Bitcoin users find these policies intolerable, then I hope that 90% of /r/Bitcoin users leave."

Ver's book focuses on the first and fourth points, as well as part of the third point, while also presenting some theories related to inappropriate behavior tied to financial motives---specifically, the small block faction established a company called Blockstream, which will build a second layer protocol on top of Bitcoin, advocating that the first layer of Bitcoin should remain limited, thus making these second layer networks necessary. Ver is not particularly concerned with the philosophy of how Bitcoin should be governed, as for him, the answer "Bitcoin is governed by miners" is satisfactory. I do not agree with either the small block faction or the large block faction on this point; I believe: the vague "we refuse to define user consensus practically" and the extreme "miners should control everything because they have aligned incentives" are both unreasonable.

![Vitalik's New Article: Reflections on the Bitcoin Block Size War])https://img-cdn.gateio.im/webp-social/moments-4fc32c571dd07dab71805dd5e951a74a.webp(

At the same time, I remember my extreme disappointment with the big block faction on some key points, which resonate in Bier's book as well. The worst point is that neither I nor Bier believes that the big block faction has ever been willing to agree to any realistic block size limit principle. A common view is that "block size is determined by the market" ------ this means miners should decide the block size according to their own will, and other miners can choose to accept or reject these blocks. I strongly oppose this and point out that this mechanism is an extreme distortion of the concept of "market". Ultimately, when the big block faction split into their own independent chain Bitcoin Cash, they ultimately abandoned this view and set a block size limit of 32 MB.

At that time, I actually did have a principled approach to determine the block size limit. Quoting a post of mine from 2018:

"Bitcoin maximizes the predictability of the cost of reading the blockchain while assuming the cost of writing to the blockchain with the lowest possible predictability. The result is excellent performance on the former metric and disastrous performance on the latter. Ethereum's current governance model achieves moderate predictability between the two."

I later reiterated this point in a tweet in 2022. Essentially, this philosophy is: we should strike a balance between the cost of writing to the chain ), i.e., transaction fees (, and the cost of reading from the chain ), i.e., the software requirements of the nodes (. Ideally, if the demand for using the blockchain increases by 100 times, we should share the pain equally, allowing the block size to increase 10 times and fees to increase 10 times ). The demand elasticity of transaction fees is close to 1, so in practice, this is basically feasible (.

![Vitalik's new article: Reflection on the Bitcoin Block Size War])https://img-cdn.gateio.im/webp-social/moments-6eb45b50fe76139d408df0944d18036c.webp(

However, this compromise approach towards ) or "concavity" ( has never been accepted by either side; it may feel too "centrally planned" for one side and too "vague" for the other. I think the fault of the big block camp is greater than that of the small block camp here; the small block camp was initially willing to moderately increase the block size ), such as Adam Back's 2/4/8 plan (, whereas the big block camp was unwilling to compromise, quickly moving from advocating a single increase to specific larger values, shifting to an overall philosophy that almost any adjustment to the block size is acceptable.