Jan 2, 2019 · 26m · a16z
a16z Podcast | Hard Forks, Hard Choices for Bitcoin
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In this a16z podcast episode, host Michael Copeland and cryptocurrency experts Adam Back and Alex Morkos analyze the technical, economic, and governance challenges surrounding Bitcoin's block size debate and hard fork scaling proposals.
How this conversation actually went
Every chapter scored 0–10 on four independent dynamics. Hover any point for the reasoning behind the score. How this is scored →
The host as informed peer 2.0 Guest teaching 5.5 Guest disagreement 1.2 The host pushing back 1.5
speaking balance: gold is the host, purple is the guest (3 minute bins)
Sharpest disagreement ▶ 15:34 Rejection of host premise on hard forks
Alex Morkos directly refutes host Copeland's suggestion that hard fork proponents want to take their Bitcoin and play elsewhere, clarifying that nobody wants a split currency.
Hardest push from the host ▶ 23:21 Host frames guest stance as opinionHost Michael Copeland intervenes to explicitly tell listeners that Adam Back's measured approach over four years is strictly his own point of view rather than settled consensus.
Biggest teaching moment ▶ 13:10 Explaining Layer 1 vs Layer 2 architectureAdam Back educates host and listeners on network layering, pointing out that around 99% of Bitcoin transactions already take place off-chain on Layer 2 systems.
The host holds their own ▶ 12:51 Synthesizing tipping vs high-value transfersHost Michael Copeland demonstrates understanding by accurately summarizing Adam's earlier explanation of how low-value tipping transactions compete with high-value transfers for block space.
the scores for every segment, with the reasoning behind each
| Chapter | Topic | The host as informed peer | Guest teaching | Guest disagreement | The host pushing back | Why |
|---|---|---|---|---|---|---|
| Soft Forks vs. Hard Forks Explained | 2 | 5 | 1 | 1 | Host Michael Copeland asks foundational questions about why block size needs to expand. Adam Back explains the fundamentals of soft forks, backward compatibility, block size constraints, and delivered security. | |
| Community Consensus and Split Currency Risks | 2 | 6 | 1 | 1 | Host acts as a facilitator asking Alex Morkos and Adam Back to detail the opposing views and proposed changes. Adam systematically breaks down six distinct proposals including BIP 100, flex cap, and his own compromise proposal. | |
| Evaluating Trade-Offs and Transaction Pressures | 3 | 5 | 1 | 2 | Host asks whether the scaling clock is ticking and synthesizes Adam's point regarding small tipping applications occupying block space. Alex details transaction demand pressures and fee market uncertainties. | |
| Off-Chain Scaling and Layer 2 Solutions | 0 | 6 | 1 | 0 | Adam delivers an uninterrupted monologue detailing Layer 1 vs Layer 2 architecture, off-chain netting, and the Lightning protocol. Host does not speak, keeping host-side scores at zero. | |
| Hard Fork Alignment and Community Governance | 2 | 5 | 2 | 2 | Host asks if hard fork advocates simply want to branch off and play elsewhere. Alex politely pushes back against this framing, clarifying that nobody wants a currency split due to network effects. | |
| Balancing Decentralization, Mining Power, and Security | 3 | 6 | 1 | 3 | Adam details mining pool centralization and the trade-offs between scale and decentralization. Host intervenes near the end to explicitly clarify to listeners that Adam's measured four-year plan represents his specific perspective. |
Statements from this episode (16)
Adam Back invented Hashcash, used in Bitcoin mining
“Back invented Hashcash, a proof-of-work system, which, among its other applications, is used in Bitcoin mining.”
Back: Bitcoin soft forks require 95% miner consensus to activate
“These things don't activate until 95% of the miners are upgraded, so, and there's a long window of warning that the upgrade is happening, six months or so.”
Back: Everyone agrees Bitcoin needs a block size increase
“If we need to increase the block size, which I think everybody agrees with at this point in time.”
Back: Bitcoin blocks are half full, half under one dollar
“The blocks are maybe a third to a half full on average, and if you look at, if you analyze the transactions in the block, about half of them are under a dollar.”
Back: Raising Bitcoin block size to 1GB would cause network failure
“If we jumped up the block size to a gigabyte now, security would fail, the network would probably fail.”
Morkos: Non-consensus hard forks could split Bitcoin into two currencies
“You might end up with two separate currencies instead of everybody moving over to the new currencies.”
Back proposes scaling Bitcoin block size limit to 8MB over four years
“So the proposal I made was to increase to two megabytes failure immediately, as soon as we can roll out change, which to be clear, any of them would take about six months to roll out. Increase to four megabytes after two years, and eight megabytes after four y…”
Morkos: Back's proposal provides crucial temporary scaling relief
“I think that's why you know, a proposal like Adams, which sort of gives you that temporary breathing room, and in the long term, more time to implement the right solution, may make a lot of sense.”
Back: 99% of Bitcoin transactions occur off the main blockchain
“Estimates are something like currently 99% of them are happening off the blockchain.”
Back: Lightning Network could scale Bitcoin capacity up to 10,000x
“There's also right now quite active work on this sort of Bitcoin enhancement called lightning, which is a best described as a kind of right caching layer for Bitcoin, which might scale Bitcoin by a factor of a thousand or 10,000.”
Back: Lightning Network implementations will yield results within six months
“There's a GitHub and a development mailing list, and there are now three, I think maybe four companies who've come forward with implementations of the early stages of it, and we're hopeful that we'll see results from that within the six-month time frame.”
Morkos: Splitting Bitcoin harms users due to monetary network effects
“Everybody would be disadvantaged if the sort of value of Bitcoin was split into two competing currencies. Money has such a strong network effect that you know, that would be bad.”
Back: Bitcoin hard forks require full ecosystem compromise to succeed
“Because of the nature of hard forks where everybody has to upgrade at once, it's essentially, you know, it's essential that all of the participants, including the users, the miners, the ecosystem players providing different kinds of services to users, that the…”
Back: Three or four colluding mining companies could influence Bitcoin policy
“You know, it's probably the case that you could, you know, If you could get collaboration from three, four companies in various parts of the world, you could start to apply some policy influence to Bitcoin.”
Back: Massively scaling Bitcoin sacrifices decentralization, turning it into PayPal
“You can scale massively and lose the decentralization, and at that point, Bitcoin loses most of its distinguishing features, and you're left with a kind of PayPal situation With all the things people gripe about with PayPal.”
Morkos: Bitcoin governance rejects top-down decision-making by industry bigwigs
“No, I don't think the point is to, you know, gather all the bigwigs in the room and make decisions. That's not how a system like Bitcoin works. I mean, everyone makes their own decision, and the idea is to have all the information come together so people can S…”