The Blocksize War (book review)

BitMEX Research has published what can be called the first history book on Bitcoin (not all of its history, but just the Blocksize War). It’s written by Jonathan Bier, who surprisingly, has no official online presence that I can find. It could as well be a pseudonym, for all I know. Either way, this book seems like it was written just for me – as in – it’s written for someone who knows Bitcoin well enough from a high level technical, historical, financial, and social context – but does not know the historical details on specifics like how the P2SH war was won^[1]Pete Rizzo and Aaron van Wirdum have a nice history-essay about the P2SH war., or how covert ASICBoost works^[2]BitMEX Research themselves have written about it in detail., and such. If you are such a clued-in-now, but clueless-about-the-past Bitcoin enthusiast^[3]For Ethereum enthusiasts, there is a chapter on the DAO as well., this book is definitely for you.

To sum it up, the Blocksize War was about Bitcoin community’s attempt to increase Bitcoin’s blocksize from 1MB to some higher number. To someone not well-versed with Bitcoin, it seems like a trivial change, and should have been a non-issue. But remember, Bitcoin hates change. The 1MB limit was famously added by Satoshi a while after Bitcoin was up and running, and therefore could be argued as a “hack”, or “kludgy fix” to a non-existing problem, etc. Raising this 1MB limit became the focal point on how Bitcoin’s consensus rules can be changed. Or whether they should change at all? Who is in charge – users, developers, miners, or businesses? The events in this book happened around the 2015-2018 time-frame, and tracking all of them chronologically is non-trivial, and this book goes a long way into making this possible. Bier was physically present in London (2015), Montreal (2015), Hong Kong (2015, 2016), Milan (2016), Stanford (2017), and the Dragon’s Den (an online forum) – which gave him a front-row seat, the view from which he captures vividly.

The book covers major Bitcoin code-forks (not to be confused with network-forks) like Bitcoin XT, Bitcoin Classic, Bitcoin Unlimited, and BTC1 – in quite some detail. Who wrote the code, who pushed the ideas forward, who put their weight behind these, what could have been their ulterior financial or personal motivations, and what eventually happened. The proceedings are livened up by colorful personalities like Mike Hearn^[4]I joined Mike’s old team at Google Zürich right after he left, and heard a few anecdotes that seemed similar in spirit to what this book says., Gavin Andresen, Gregory Maxwell, Faketoshi, Jihan Wu, Adam Beck, Pieter Wuille, Vitalik Buterin, Roger Ver, Samson Mow’s UASF hats, Brian Armstrong, Theymos, Jeff Garzik, Wladimir van der Laan, and others (not to mention Satoshi Nakamoto, whose purported 2015 email from the @visionmail account, I had no idea about). There are basic technical descriptions of important ideas like soft-forks, hard-forks, wipeout-protection, miner-signaling vs miner-voting, whether IETF’s idea of “rough consensus” applies to Bitcoin, the curious nature of BIP-148’s meta-soft-fork, ASICBoost, segwit, Lightning, Bitcoin Cash’s difficulty adjustment algorithm’s bugs, and so forth.

The one key observation that Bier makes is that the existing consensus rule set of Bitcoin acts as a key Schelling Point in any disagreement on whether to change Bitcoin or not, and if enough people defend this Schelling Point, it persists. This idea is reinforced through the book (though explicitly mentioned only once), and eventually, if that’s the only thing you take away from the book – that’d be a good thing. Additionally, history lessons from this book are important and we have to appreciate that BIP-148 might not have worked at all, and could have been catastrophically bad for Bitcoin^[5]Anthony Towns recently speculated this exact same thing.. Just that it happened to work out (and not work, per se) doesn’t mean that it will work out again. Bitcoin wants to add Taproot and Schnorr signatures now, and we are witnessing the beginnings of another skirmish (if not a full-on war). I hope that this time, given that the consensus-rule change itself is acceptable to everyone, a meta-consensus on how to change consensus-rules will emerge. As Bier says in his book, Bitcoin has to be ready when the nation-state attacks begin, and these scars should help.