A Civil War Over One Megabyte
Between 2015 and 2017, the Bitcoin community was torn apart by a conflict known as the 'block size war'. At its heart was a simple, yet profound, disagreement over a single technical parameter: the 1-megabyte limit on the size of blocks in Bitcoin's blockchain.
One faction, the 'big blockers', argued for a straightforward increase to this limit, believing it was the only way to keep transaction fees low and transaction times fast as the network grew. They envisioned Bitcoin as a global payment system for daily use. On the other side were the 'small blockers', who feared that larger blocks would make it more expensive for individuals to run their own nodes, leading to centralization and compromising the network's core value proposition. They advocated for scaling through smarter, more efficient use of the existing block space and by moving smaller transactions to secondary layers.
SegWit: The Complicated Compromise
Segregated Witness, or SegWit, emerged as the small blockers' championed solution. Activated in August 2017, it was an intricate software upgrade, or 'soft fork', that didn't directly increase the 1MB block size limit. Instead, it cleverly restructured transaction data by separating, or 'segregating', the digital signatures (the 'witness') from the rest of the transaction. Because this witness data took up a lot of space, moving it effectively created more room in each block, allowing more transactions to fit. Proponents sold it on two main benefits: it would immediately help lower fees by increasing capacity and, crucially, it would fix a long-standing bug called 'transaction malleability'. Fixing this bug was the essential key to unlocking secure 'Layer 2' solutions, most notably the Lightning Network, which was central to the small-block vision for scaling.
The Prophecy of a Two-Tier System
Critics of SegWit had a host of complaints. They argued it was needlessly complex, that it didn't provide enough of a capacity increase, and that it was a power grab by a small group of developers. But the most prescient criticism was less about the technology itself and more about the future it would create. Opponents argued that by choosing a path that intentionally kept the main blockchain constrained, SegWit was a tacit admission that Bitcoin's base layer would never be for everyone. They predicted it would inevitably lead to a two-tier system: a highly expensive main chain for large, important settlements, and a collection of secondary layers for everyone else. In this future, the dream of 'peer-to-peer electronic cash' for the masses would be abandoned in favor of a system where using the main network for a small payment would become prohibitively expensive.
High Fees and the Rise of Lightning
Years later, that's largely the reality we live in. While SegWit did help alleviate fee pressure for a time, it was not a permanent solution. Whenever network demand surges—whether from a bull market or new uses like Ordinals—on-chain transaction fees can still skyrocket, pricing out smaller users just as critics warned. This has made the Lightning Network not just an option, but a necessity for anyone hoping to use Bitcoin for fast, cheap payments. The 'big blocker' prediction that constraining the base layer would make it a settlement network for the rich has, in many ways, come to pass. This has led to its own set of criticisms, with some developers arguing that the Lightning Network's user experience is still challenging and that it may be pushing users toward easier, custodial solutions, reintroducing the very centralization the small blockers fought to avoid.
