A technical presentation by Greg Maxwell, a Bitcoin Core contributor and chief technology officer at Blockstream, recently took place at a SF Bitcoin Developers event. The discussion centered on the i
A technical presentation by Greg Maxwell, a Bitcoin Core contributor and chief technology officer at Blockstream, recently took place at a SF Bitcoin Developers event. The discussion centered on the impending 0.15 release of Bitcoin Core. When Michael Tidwell, host of Blocktime, posed a question during the Q&A segment, he turned to the topic of SegWit2x and what would occur if that proposal's hard fork component were to secure the majority of mining hashpower.
The origins of SegWit2x trace back to the New York Agreement, wherein major industry participants and the dominant share of miners consented to pursue a hard fork raising the block weight threshold, with implementation targeted for November. However, some organizations that signed onto the accord have since either pulled back their support or issued clarifications that their backing applied only to certain components, excluding the hard fork portion.
Maxwell was direct regarding Bitcoin Core's position: the project's main developers oppose SegWit2x and will not incorporate it into their software. His assessment of its prospects drew a parallel to mining dynamics. "I think it's unlikely that [SegWit2x] will get more work behind it for the same reason that miners are mining [Bitcoin Cash] right now," Maxwell explained. His reasoning centered on profit incentives: "Miners are going to follow the money."
Maxwell's worldview treats Bitcoin as fundamentally a set of rules rather than a system defined by whichever chain possesses the greatest accumulated computational effort. In his conception, rule compliance outweighs raw hashpower. "More work is always secondary to following the rules of Bitcoin," he said. He marshaled an analogy to strengthen the point. If Ethereum somehow received greater total mining energy directed toward it than Bitcoin did, that wouldn't suddenly transform Ethereum into Bitcoin in his eyes. "I don't just suddenly go, 'Oh, Ethereum is Bitcoin now because it's got more joules of energy pumped into its security,'" he offered.
Maxwell didn't dismiss hard forks as impossible, but he underscored significant obstacles to achieving them. A hard fork would need something essential to succeed: genuine grassroots support from the user base at large. "But it has to be a hard fork the users as a whole choose to do," he stressed. The practical challenge is substantial. "Maybe that's really hard to achieve, especially since we can do so many things without hard forks," he noted.
Bitcoin Core's development philosophy favors soft forks instead—modifications that remain compatible with older node software and that users can activate selectively. Maxwell outlined why this matters for security architecture. "That's an important part of the security model because if you can easily change Bitcoin to take one controversial, probably okay change, then you can change it in lots of other ways as well," he elaborated. He captured Bitcoin's essential promise as a "digital asset that isn't going to change out from under you."
One scenario Maxwell sketched out: introduce a soft fork first, then deploy a hard fork later to handle resulting complications and technical overhead. Hard forks framed as cleanup operations might garner stronger backing. A broader principle governs which hard fork concepts have realistic chances. "There is a proportional relationship [between] the distance you have to the code — and the operation of the system — and how viable you think some of these proposals are," Maxwell reflected.
The dialogue moved into speculative territory—what if the mining ecosystem united around SegWit2x? Maxwell's answer hinged on a prerequisite condition: "I think that if users as a whole were adopting it, then the people that are developing Bitcoin today would go and do something else instead," he proposed.
But picture an alternate reality where miners endorsed SegWit2x yet the broader user community stayed loyal to the established chain. Under those circumstances, Maxwell suggested, Bitcoin Core engineers would have recourse to a drastic remedy: altering Bitcoin's proof-of-work algorithm, currently SHA-256. Maxwell rejects the notion that SHA-256 constitutes a non-negotiable pillar of Bitcoin's identity; he even anticipated it might require replacement someday for cryptographic security reasons.
The problem: changing the algorithm would render all mining equipment obsolete and worthless. Maxwell termed this approach the "nuclear option" for its destructive impact. Yet he saw rational justification for triggering it when circumstances became dire. "When you have no other choice, you do it because duh," he said plainly. The underlying logic was stark: "Do you choose a system that's non-functional and insecure or do you choose a system that works?"
