Exploring the "rigidity" phenomenon of the Bitcoin network protocol

Explaining why we should continue striving to improve the Bitcoin protocol.

Written by: Jameson Lopp

Translated by: LlamaC

(Portfolio: Burning Man 2016, about Tomo: eth Foundation Illustrator)

Recommended note: This article once again explores the phenomenon of "ossification" in the Bitcoin network protocol. As Bitcoin becomes more popular and the network grows, it becomes increasingly difficult to make changes to the protocol, which seems to be an inevitable natural process. The author believes that although ossification is inevitable, Bitcoin should continue to make necessary protocol improvements through careful and broad discussion to maintain its long-term vitality and security.

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In the context of network protocols, ossification refers to the slowing down of their evolution and change. This seems to be a law of network physics. Essentially, as a network protocol gains wider adoption, the "mass" of the network increases, and the effort required to coordinate software updates among protocol users to change the network's direction increases dramatically. Ultimately, the ability to safely activate any protocol change is crushed by the sheer weight of the network due to the inability to coordinate a large number of decentralized participants.

Therefore, the ossification of Bitcoin is inevitable. But as of today, we are still debating whether we should proactively ossify the protocol. I personally strongly oppose this position and believe there is still too much room for improvement; it is too early to give up on changes to the base protocol.

I propose to you that Bitcoin can only remain vibrant, relevant, and secure in the long term by being willing to implement reasonable, broadly beneficial protocol improvements in a careful, consensus-driven manner. Freezing progress at this point is arrogant, ahistorical, and a rejection of the original vision that created Bitcoin. Thoughtful, ongoing evolution is key to Bitcoin's long-term value proposition. Digital gold is superior to physical gold precisely because it is not inert. What I mean is: the properties of physical gold cannot be improved, so financial innovation in gold is achieved through centralized IOUs... but Bitcoin's properties can be improved, enhancing its permissionless use.

Learning from History

Bitcoin has only a 15-year history and has already undergone many consensus changes and upgrades. It is too early to assume that the current point in time is the ideal stopping point. The protocol needs to adapt over time to remain viable.

We should learn from other popular network protocols like SMTP. If Bitcoin ossifies, developers will build increasingly complex layers on top of it to add needed functionality. Complexity introduces bugs and vulnerabilities.

The Death of Decentralized Email: A Historical Review of the Decades-Long Centralization and Killing of the Email Protocol

This is not a criticism of complex layers like BitcoinOS / BitVM / Botanix's Spiderchain / Citrea's zero-knowledge rollup—they are doing the best they can with the available toolset. While we do not want Bitcoin to become an all-encompassing protocol, if adding low-level functionality at the base layer can significantly reduce the complexity of building features at higher layers, then it makes sense to do so.

Potential Paths Forward

Many ideal features, such as covenants, vaults, and payment pools, require base layer upgrades. Building these features clearly into the protocol itself is far better than using hacky overlay layers. A base layer with more building blocks opens up new design space for Bitcoin.

Regarding the news that Bitcoin second-layer developers want to introduce OP_CAT, emphasizing the benefits of OP_CAT for multiple projects and how it will accelerate permissionless innovation. He believes that the idea that all improvements can be made at layers outside the base protocol is usually proposed by those who have not tried to build other layers.

Cautious, well-tested upgrades that are thoroughly discussed and reach community consensus do not harm property rights or Bitcoin's core stable monetary proposition. Upgrades reflect the will of the users, not something imposed upon them.

I believe Bitcoin's potential far exceeds what we have achieved so far. I see the Bitcoin blockchain as a cryptographic accumulator for various systems that can be anchored to it. But we have only scratched the surface of what is possible. If we ossify today, when building permissionless second-layer networks is so difficult, we will tie developers' hands and greatly limit experimentation to find the most valuable uses for block space.

People often say we don't need to change Bitcoin because we can scale through other layers. Sure, it would be great if developers were unrestricted! We simply do not have all the necessary primitive building blocks at the base layer to easily launch permissionless second-layer networks. For example, we could make Bitcoin script powerful again.

Rusty Russell explains his great script restoration project: Bitcoin version v0.3.1 disabled many script opcodes, the most famous being OP_CAT. Re-enabling these opcodes would unlock a lot of potential, and in modern Bitcoin systems, there are some additional opcodes that would complement them well (such as key addition). This talk aims to propose a coherent model to make Bitcoin script as powerful as possible while avoiding the pitfalls that led to its initial weakening.

Note that we implemented three different forks to enable three different building blocks to create the Lightning Network. Without the features enabled by these forks, the Lightning protocol would be much more cumbersome and the game theory would not be as robust.

We could do other soft forks, such as SIGHASH_ANYPREVOUT, which would greatly enhance the Lightning Network and allow for the existence of channel factories, increasing Lightning's efficiency by several orders of magnitude. We could do some privacy-enhancing forks, such as cross-input signature aggregation. We could also do forks like OP_CTV to improve self-custody security through covenants and vaults. We can see many potential futures, but moving in these directions is becoming increasingly difficult.

On Sovereignty and Self-Custody

Scaling is another long-term issue. Greg Maxwell said in 2015:

If the system's cost is too high, people will be forced to trust third parties rather than independently enforce system rules. If the Bitcoin blockchain uses too many resources relative to available technology, Bitcoin will lose its competitive advantage over traditional systems because the cost of verification will be too high (making it unaffordable for many users), forcing trust back into the system. If capacity is too low and our transaction methods are too inefficient, the cost of accessing the chain for dispute resolution will be too high, again pushing trust back into the system.

The decentralization of validation that won the block size debate is only part of the story. The decentralization of economic participants is also important for Bitcoin's long-term success. Remember, it is not the will of the nodes that decides Bitcoin's future, but the will of the economically majority nodes. Bitcoin's economic participants include miners, holders, and traders (including companies and custodians). The key is—if the number of economically relevant nodes decreases due to centralization, and most Bitcoin users cannot self-custody due to cost, we should expect the "governance" of the protocol to become more centralized and fragile.

In the current state of Bitcoin, globally, perhaps only 100 million entities can access Bitcoin's basic properties. In a world of 8 billion people, this situation will not create a new type of decentralized currency that changes the landscape of value and scarcity, but merely creates a new elite class, who, over time, will initially create prosperity and eventually degenerate into bread and circuses like all elite groups in history. For the first time, Bitcoin has the potential to do more than just transfer power from one elite group to another, but only if we continue to strive for maximum decentralization by improving the protocol and enabling more people worldwide to access Bitcoin's basic properties.

Note that the argument "we can do anything we want on other layers" often ignores the fact that any layer built on top of Bitcoin cannot provide the same security model as the base layer. Every time you build a layer on top of Bitcoin, you need to create a whole new set of game theory and trade-offs for self-custody users of that layer.

The Ossified Mindset

Ossificationists believe that Bitcoin has already achieved its core functions as sound money and a store of value. Further changes, even well-intentioned, introduce unnecessary risks that could undermine the very properties that make Bitcoin valuable. By ossifying the protocol, we ensure that Bitcoin remains a trustworthy, decentralized, and immutable monetary system in the long term.

1. Maintaining Trust in Bitcoin's Fundamental Properties:

Bitcoin's main value proposition is its fixed supply and immutability. Any change to the protocol, even a soft fork, could undermine confidence in these core attributes. Some claim that the ability to change the protocol reduces confidence in the inflation schedule, no matter how well-intentioned.

2. Reducing Developer Control and Centralization Risk:

Allowing continued modifications to Bitcoin gives developers too much influence over the protocol. This creates centralization risk, as a small group could change Bitcoin's properties.

3. Guarding Against Unintended Consequences:

Even well-intentioned and thoroughly tested changes can have unforeseen effects on the network. As Bitcoin's value and importance grow, the potential impact of these unintended consequences becomes more severe.

4. Increasing Difficulty of Changes as Adoption Grows:

As Bitcoin's adoption increases and more economic value is built on top of it, any change becomes riskier and more disruptive. Ossificationists believe the protocol should reach a stable point, similar to other foundational protocols like TCP/IP or power outlet standards.

5. Maintaining Bitcoin's Function as Sound Money:

Bitcoin's main goal is to serve as a new monetary system free from debasement. Ossification ensures this core function is preserved, without risking changes to its fundamental properties for potentially unnecessary improvements.

Common Arguments for Ossification

Ossificationists believe Bitcoin currently works very well, and the protocol rules should be extremely resistant to change to maintain its core value proposition as an immutable, non-inflationary, apolitical form of money. Even well-intentioned changes carry great risk and could jeopardize Bitcoin's long-term success and stability.

1. Don't Fix What Isn't Broken

Bitcoin has succeeded under the existing protocol, growing its market cap from $0 to $1.4 trillion in just 15 years. There is no need to risk undermining this success with hasty or unnecessary changes.

2. Stability Is Crucial

Bitcoin's core value proposition is its stability and predictability. Protocol rules should not be changed lightly. Frequent modifications undermine confidence in Bitcoin's immutable nature.

3. Think Twice Before Acting

Changing the Bitcoin protocol is an extremely serious task, akin to amending a constitution or designing laws meant to last for centuries. Any change must be slow, careful, and conservative, and only implemented after considering all long-term effects.

4. The Higher the Stakes, the Steadier the Hand

The bigger and more successful Bitcoin becomes, the more important it is to be cautious with any protocol changes. With over a trillion dollars in value and nation-state buyers involved, we cannot afford mistakes or unnecessary risks.

5. The Road to Hell Is Paved with Good Intentions

Even well-intentioned protocol changes can have unpredictable negative effects, such as harming the economic interests of miners, developers, and holders. The potential risks may outweigh any theoretical benefits.

6. Keep It Simple, Stupid

Not every new feature or improvement needs to be implemented at the base protocol layer. Many things can be done at higher layers, such as Layer 2 or Layer 3, without jeopardizing Bitcoin's core security model and stability.

7. Immutable Money in a Changing World

Constant "improvements" and protocol changes go against Bitcoin's promise as a stable, apolitical currency and settlement network. Ossification is a feature that prevents Bitcoin from being captured by special interest groups or undergoing unpredictable mutations.

8. Bitcoin Should Only Be Money

Using block space for tokens/NFTs and other non-monetary purposes only fuels fads and pump-and-dump scams, crowding out legitimate users who want to use Bitcoin as money.

My Response to Ossification Arguments

Maintaining Trust in Bitcoin's Fundamental Properties:

Trust in Bitcoin's properties and the ability to resist bad ideas ultimately depend on the governance process for protocol changes, not on making changes impossible. Bitcoin is crypto-anarchism, a system that defaults to indifference, which is a powerful veto. You either believe Bitcoin's governance has served us well so far, or you think we've just been lucky and the whole system could collapse at any time.

Jameson Lopp - Keynote on Using Blockchain to Disrupt Bureaucracy

Reducing Developer Control and Centralization Risk:

Similarly, you either believe the game theory around protocol changes is sound, or we've just been lucky so far. Bitcoin developers cannot force anyone to run code they disagree with.

Who Controls Bitcoin Core? Understanding How Bitcoin Development Works.

Moreover, the internal development process is extremely challenging. Most proposed rule and code changes do not make it through the gauntlet.

The Challenges Faced by Bitcoin Core Contributors: A Deep Dive into the History of Accepted and Rejected Code Changes in the Bitcoin Core Project.

To summarize my research from four years ago:

After traversing all rejected Bitcoin Core pull requests, we found:

• 9,011,209 total rejected lines of added code
• 6,279,435 total rejected lines of deleted code

This means 15,290,644 lines of code changes were rejected, compared to 3,651,046 lines of code that were accepted!

This shows that as of writing, only 19% of proposed code change lines were accepted into Bitcoin Core.

Preventing Unintended Consequences:

In my view, fear of unknown unknowns and unintended consequences is not a valid argument. Why? Because every decision has unknown unknowns. Modifying the protocol has unknown unknowns. Not modifying it also has unknown unknowns. There are always unquantifiable unknown unknowns, so this argument is actually self-contradictory. Vigilance is key—this is where Bitcoin's antifragility lies.

Increasing Difficulty of Changes as Adoption Grows:

I don't think this is actually a point of disagreement between the two sides. As the network grows and its value increases, it has always become harder to change, and will continue to do so in the future.

Maintaining Bitcoin's Function as Sound Money:

The world in which Bitcoin operates will never ossify. The world will constantly throw new problems at Bitcoin; if it cannot adapt and solve them, we should expect rough and possibly centralized solutions to be forcibly added. This is what led to the decline of SMTP. The key is that Bitcoin's properties cannot be guaranteed to be preserved through ossification.

Don't Fix What Isn't Broken

No one is pushing for hasty change, and no one can seriously argue that Bitcoin will "collapse" without a particular feature. But what we can say is that the nature of Bitcoin's use will change. Over the past 15 years, it has already changed significantly.

Stability Is Crucial

Since Satoshi left the project, Bitcoin's rules have never been "changed at will." Satoshi once made changes unilaterally without consulting others. I notice some influential people disparage Bitcoin developers as "tinkerers," which is far from the truth. We can observe that due to developers' extreme caution, the pace of change in Bitcoin has slowed dramatically over the years.

Think Twice Before Acting

Indeed, slow and steady improvements that are thoroughly validated are exactly what innovators are asking for.

The Higher the Stakes, the Steadier the Hand

We absolutely should strive to avoid mistakes. We should also have confidence that mistakes are not irreparable. For example, Bitcoin Core has introduced many bugs, but all have been fixed without incident. Even when the Bitcoin network suffered a consensus failure, it was restored within hours due to the vigilance of network participants. This is a fundamental feature of Bitcoin's antifragility.

Bitcoin does not exist in a vacuum. In a sense, it is a living organism. No life form can thrive through stagnation.

Bitcoin is the Mycelium of Money — By Brandon Quittem

The Road to Hell Is Paved with Good Intentions

I think this is another self-contradictory argument. The Bitcoin ecosystem is extremely complex, with countless moving parts and participants. As parts of the system outside the protocol itself change over time, we should be prepared for the unforeseen consequences these changes bring.

Keep It Simple, Stupid

I think this is another point generally agreed upon by both sides. For the base layer, the most important changes should be those that can have a huge impact on other permissionless layers, enabling them to experiment freely without worrying about base layer issues.

Immutable Money in a Changing World

This seems to be another issue of not believing in the game theory behind Bitcoin governance. I think if you don't believe in the system's inherent checks and balances, then you don't truly believe in Bitcoin.

Jameson Lopp points out in his post that public permissionless consensus systems (such as public blockchains) allow users to use them without trusting any single individual, but users must collectively trust all participants.

As I will mention later, ossification itself can also make Bitcoin susceptible to capture by special interest groups. The answer is not paralysis, but vigilance and the ability to adapt to new pressures and adversaries!

Bitcoin Should Only Be Money

The debate over which use cases for Bitcoin should be considered spam has been going on for a long time. I don't find this debate particularly interesting because it ultimately comes down to people arguing about subjective value, while we can empirically observe that non-financial uses of block space have objective value to people—they are willing to pay for the privilege.

On a technical level, Bitcoin is a data store; the blockchain is essentially an append-only log with several other interesting properties. Therefore, people have been using Bitcoin for non-financial purposes for over a decade. As I wrote eight years ago, it is precisely the permanence and non-overwritability of this data that attracts people to use it for non-financial purposes.

Bitcoin: The Trust Anchor in the Blockchain Ocean. Bitcoin is the most powerful permissionless blockchain in terms of computational security because it invests the most resources in securing itself through a proof-of-work process.

We do not know what the long-term market for block space will look like—that is, which uses of block space will be found to provide the greatest utility and value. With each halving, this question becomes more important. I believe that more features and more experimental layers mean we are more likely to find the highest-value use cases for block space. For example, perhaps this could be powering zero-knowledge rollups. We don't know yet, so I think we should let innovators continue to explore the potential design space.

In my view, what do all these arguments boil down to?

Jameson Lopp discusses the relationship between "settlers" and "innovators" in the Bitcoin ecosystem on X.

Frequently Asked Questions

What if all these non-bug-fix protocol change ideas are "nice but unnecessary"? Is this just Bitcoin tech geeks running wild in their ivory-tower technical interests, which are not strictly necessary for Bitcoin to one day become global money?

I don't think it's a matter of necessity or not. I think it's about finding a path, exploring Bitcoin's design space, and maximizing the system's value. To be clear, we could ossify Bitcoin right now, and it would continue to function just fine for a long time, until we encounter a critical issue like quantum computing or the timestamp overflow. But due to development constraints, the nature of Bitcoin itself will evolve differently.

Where is your "stopping point" for changes? When is Bitcoin good enough?

We should continue improving Bitcoin until we can no longer improve it. We have already seen a sharp decline in Bitcoin improvement proposals since 2017—now averaging less than one per month. And many proposals don't even come with activation guidelines because developers don't want to go through that level of scrutiny. As a result, we are losing protocol development talent, which further exacerbates the slowdown.

Should protocol changes be limited to "bug fixes and maintenance" and not include "new features"?

This is certainly an option, and maybe we will eventually go down this path. But I don't think we should be satisfied with the status quo.

Describe scenarios in which the Bitcoin ecosystem might agree to support and promote soft fork or hard fork changes

Any critical issue that threatens the continued operation of the system. However, the nature of ossification may make urgent fixes in the distant future very tricky.

1. Imagine we have not made any changes to Bitcoin's consensus rules for decades. So perhaps the current batch of Bitcoin protocol developers have never actually experienced modifying consensus. In this case, it is not a good sign for us.
2. Consider that there are some potential issues, and we do not know exactly when they will become critical. The nature of ossification means we will keep postponing addressing these issues... possibly until it's too late. I recommend watching my recent talk on quantum computing for a concrete example of this situation.

Jameson Lopp explores the risks posed by quantum computers in his keynote "Protecting Satoshi's Stash" at the 2024 Bitcoin Future Conference. This is a must-watch for anyone serious about protecting their Bitcoin holdings.

Conclusion

We should strive to make changes to Bitcoin to enhance its functionality and allow more permissionless systems to anchor to it. I think we all agree that Bitcoin should not become a hodgepodge protocol like EVM-based networks, but as things stand, developers who want to innovate find it very difficult to do so without creating extremely complex and burdensome logic.

Ossification is complacency. Yes, we all agree Bitcoin is great. But I do not agree that Bitcoin has reached its full potential. I think complacency is one of the greatest threats facing Bitcoin—we cannot rest on our laurels.

Technology is inherently deflationary. Bitcoin's consensus rules should prioritize security and maintain decentralization of the system in as many ways as possible. This includes not only node operators but also users of block space. After all, if someone cannot use block space due to price, they certainly will not run a full node either. I also believe we should enhance developers' ability to build permissionless second layers so we can continue to explore potential use cases for block space as a cryptographic accumulator, thus increasing our chances of finding a path to sustainable demand and permanently paying for Bitcoin's thermodynamic security of block space.

Should we let Bitcoin's future be driven by optimism or pessimism?

Jameson Lopp posted on X comparing the positions of Bitcoin innovators and ossifiers, arguing that Bitcoin's antifragility or fragility depends on individual belief.

To be clear, caution is crucial. You will never see me claim anywhere that "Bitcoin must implement X feature or it will fail." In my view, Bitcoin's success is actually one of the factors that makes it harder to improve.

Jameson Lopp argues in his post that Bitcoin's exchange rate may continue to rise even as its unique properties are gradually eroded. He warns that we should not let newfound wealth lull us into complacency.

But if we allow ourselves to be paralyzed by fear, we will sacrifice potential paths forward and greatly limit the exploration of Bitcoin's design space, which I believe will naturally lead to limiting its adoption, use cases, and strengthening of valuable properties.

The torment of precautions often exceeds the dangers to be avoided. - Napoleon Bonaparte

I want to remind everyone, because I see conflict ahead. Consider the motivation for wanting to improve the Bitcoin protocol. The only reason you care about doing so is if you are a direct user of the protocol. In other words, protocol improvements only matter to those who self-custody. If you use a trusted third party to store your funds, you don't care how they use the protocol.

Jameson Lopp posted on X, pointing out that TradFi's adoption of Bitcoin does not care about improving the protocol and scaling the network, because they are not interested in self-custody. He predicts Bitcoin's next battle is about to begin.

Perhaps Bitcoin has already ossified, and everything written above is in vain. Only with enough hindsight will we know for sure. The world will never stop evolving, and we must ask ourselves whether we want Bitcoin to evolve with it or be left behind.

Let's move forward together.

Forward.