Coin Stories: Adam Back Part 2 – Core vs. Knots: Spam, Censorship, and Bitcoin's Future

Date: October 2, 2025
Host: Natalie Brunell
Guest: Adam Back (Blockstream CEO, Hashcash inventor)

Overview

This episode dives into the hot-button debate within the Bitcoin community: the "Core vs. Knots" controversy, centering on how the Bitcoin protocol should address blockchain 'spam' (e.g., non-transactional data and meme coins), censorship resistance, and the risks of altering Bitcoin’s software. Adam Back, a key figure in crypto history, brings a wealth of technical and philosophical insight into why these seemingly technical disputes tap deep fears about Bitcoin's future, precedents of censorship, and the unintended consequences of protocol changes.

Key Discussion Points & Insights

1. Understanding Core vs. Knots & the Spam Debate

[01:10]

• Definition of Blockchain 'Spam':

  • Refers to non-transactional data being inscribed on the Bitcoin blockchain—images, meme coins, etc.—consuming space without contributing to monetary transactions.
  • Notable statistic: “Bitmex research put out... three and a half million images in the bitcoin blockchain... about 105 million non-transactional things.” (Adam Back, [01:22])

• Market Dynamics and Spam:

  • Spam like images is minimized by market mechanisms (fees relative to data size), but still clogs the blockchain and UTXO set.
  • Meme coins, tokens, and so-called “color coins” are being layered onto Bitcoin, reminiscent of altcoin activity.

• UTXO Set Bloat:

  • Non-monetary activity creates millions of unspent outputs, eventually putting stress on node resources—mainly RAM.
    • “If you get a small computer... the thing that is most expensive and harder to upgrade is the ram... [UTXO set] matters.” (Adam Back, [06:04])

• Legitimacy Spectrum:

  • Spam is not a binary; some uses (Tether, company shares) may be legitimate for others. “It's a full spectrum of things... making a judgment about what's legitimate is a slippery slope.” (A, [08:39])

2. Change Proposals and the ‘Knots’ Approach

[11:32]

• Knots vs Core:

  • Knots is a fork of Core proposing tighter spam controls. Natalie seeks Adam’s view on whether such changes risk Bitcoin’s core principles.
  • Adam supports extreme caution: “People are probably losing track of the operational risks of running peer to peer software.” (A, [12:52])

• Analogy to Broader Internet Tools:

  • Experiences with anonymizing email and Tor underline that all privacy-enabling systems get abused, but kneejerk clampdowns risk dangerous precedents for freedom.

3. The Precedent Problem: Apple vs. FBI as Cautionary Tale

[15:50]

• Discussion of Apple’s Refusal to Add a Backdoor:

  • If you build or expose a method to censor, you risk being compelled in the future for any reason.
  • “If you build in the interest of limiting spam or deleting things from a blockchain... now you've probably introduced the risk of compelled... cooperation, to do the same for any number of law enforcement things.” (A, [16:36])

• Censorship Resistance Is a Non-Negotiable:

  • Adam: “It should be unambiguous to everybody that it would be extremely bad for Bitcoin’s value proposition if people built and set a precedent... that they're able to censor or freeze or edit transactions. It's kind of the opposite of Bitcoin’s value proposition.” (A, [17:38])

4. Why Is the Debate So Emotional?

[25:02]

• Community Civil War:

  • The deepest conflicts occur within tribes who care most about the same thing. “You get the fiercest battles between people on the same mission with the same desired outcome.” (A)
  • Many users lack awareness of protocol history, or how law enforcement and precedent interact with digital systems.

• The Technical Reality:

  • Spam is hard—by design— to censor; blocking one type leads to cat-and-mouse games and worse performance for everyone.
  • Example: “If 90% of nodes are trying to block... has zero effects on your ability to reload those and to get them mined... the miners are economically incentivized...” (A, [27:31])

5. Technical, Social, and Game-Theoretical Nuances

[31:30]

• Peer-to-Peer Network Dynamics:

  • Anti-spam measures (e.g. filtering transactions) can slow propagation and degrade node performance.
  • “That is an unfortunate somewhat negative side effect of trying to control spam. But it's manageable...” (A)

• Ultimate Power Lies with Miners:

  • Only miners can actually filter transactions at the protocol level—but asking them to do so is not tenable, given strong economic incentives not to self-censor.
  • “The only real way to stop spam is to persuade the miners to stop it.” (A, [36:55])
  • “As long as there is economic demand and as an industry that can continue making money, it's probably not going to stop.” (A, [41:31])

• Censorship Resistance Is Also an 'Arms Race':

  • Any attempt to filter spam will be met with countermeasures, making the whole system less efficient (and never actually achieving total spam elimination).

6. Historical Parallels & Slippery Slopes

[43:36]

• What if Miners/Developers Try to Censor?

  • Experience from other digital fights: always starts with 'just block the bad stuff', but governments and precedent quickly expand what counts as blockable.
  • “This is the first time I've seen the users and enthusiasts for the system use that hot button tactic [“think of the children”] that governments use to ban...” (A, [48:38])

• Legal/Practical Realities:

  • Illegal content has been inserted into Bitcoin since at least 2018; software changes now cannot erase or prevent it.
  • “Anybody could post something illegal in any of these formats. They could have done that in Opreturn...for the last decade.” (A, [49:51])
  • Users are not liable for data they did not knowingly seek out (“legal concept”), which weakens some of the risk narratives.

7. Development Process, Miscommunications, and Misinformation

[50:33]

• How Consensus Works:

  • 'Core' is not a corporation but a loose set of volunteers, often underappreciated for maintenance work and misunderstood in the public debate.
  • Missteps in communication fueled confusion and more emotional reaction online.

• Viral Misinformation (re: Saylor’s Video):

  • Michael Saylor did not endorse Knots; video was a mashup by a third party. Caution is needed with viral (potentially misleading) content.
  • “Saylor didn't talk about knots. It's a couple of years before this drama's going on, so he didn't endorse anything. He was just saying... you have to be very careful with mission critical systems.” (A, [52:15])

Notable Quotes & Memorable Moments

• On Censorship-Resistance:

  • “Bitcoin is supposed to be final and censorship resistant and unseasonable payments.” (Adam Back, [00:00], [16:36])

• On Precedent and Compulsion:

  • “If you set a precedent for [spam mitigation], now you've probably introduced the risk of compelled cooperation to do the same for any number of law enforcement things.” (A, [00:24], [16:43])

• On Developer Discretion:

  • “It should be unambiguous to everybody that it would be extremely bad for Bitcoin’s value proposition if people built and set a precedent... to censor or freeze or edit transactions.” (A, [17:38])

• On Emotional Intensity in Community:

  • “You get the fiercest battles between people on the same mission with the same desired outcome... [They] are very concerned about the robustness and future survival of bitcoin.” (A, [25:09])

• On Attempts to Stop Spam:

  • “The more you constrain something, the more profitable it gets... The more you're successful at persuading people not to do it, the more they are incentivized to pay and the more profitable it gets. So... you’re never going to be able to stop it.” (A, [41:25])

• On Miner Economics:

  • “It’s like a billion dollar industry, basically, the spam… the miners have collected… $800 million in fees… Are they going to be easy to persuade not to do it? Probably not.” (A, [36:55], [38:50])

• On Community Hot Button Tactics:

  • “This is the first time I've seen the users and enthusiasts for the system use that hot button tactic that governments use to ban… to attack themselves unintentionally.” (A, [48:40])

Important Segment Timestamps

• What is the Core vs. Knots debate?

  • [01:10]–[09:05]

• Knots’ anti-spam approach and risks of protocol change

  • [11:32]–[13:52]

• Apple vs FBI as a protocol precedent

  • [15:50]–[18:00]

• Censorship-resistance, legal precedent, and the Four Horsemen problem

  • [17:38]–[22:42]

• Why the emotion? The challenge of spam in a censorship-resistant network

  • [25:02]–[31:30]

• Propagation impacts and why miner incentives matter

  • [31:30]–[41:30]

• Why policy interventions and miner appeals fail

  • [41:30]–[43:36]

• Development, misinformation, and responsibility

  • [50:33]–[53:21]

Conclusion

Adam Back calls for humility and caution, warning of the grave risks in seemingly simple changes to Bitcoin’s protocol: “Bitcoin is the most mission critical system in the world... you have to be very careful.” (A, [52:15]). Both the technical realities of censorship-resistance and the painful lessons from other peer-to-peer systems make 'fixing spam' intractable without risking Bitcoin’s founding principles.

Natalie summarizes:
“We do really, I think, have to be very careful about evaluating any proposed changes to Bitcoin. We do not want to introduce any ability to censor.” ([51:48])

This episode serves as a vital primer for anyone seeking to understand the technical, economic, and philosophical tensions at the heart of today’s Bitcoin development debates.