The block size war: who decides Bitcoin's rules
The 2015–2017 fight over bigger blocks, Bitcoin XT, SegWit and the fork, and what it taught about governance.
Share this page
The question
Should blocks be made much bigger to fit more transactions, or kept small so ordinary people can run full nodes and verify everything themselves?
What happened
Proposals like Bitcoin XT failed to win support. SegWit, a change that also increased capacity, activated in August 2017 after pressure from users running nodes. Supporters of big blocks split off and created Bitcoin Cash.
The lesson
No company, miner group or developer can force a rule change. Changes stick only when the people running nodes accept them.
FAQ
- Who decides Bitcoin's rules?
- Effectively, the users who run full nodes and choose which software to run. Developers propose, miners order transactions, but nodes enforce the rules.
On the site
Original bitcointalk.org threads
- Bitcoin XT #REKT · 4,528 replies / 379,026 views (as of 13 Oct 2026)
- 20MB Fork · 2,499 replies / 154,828 views (as of 13 Oct 2026)
- SegWit questions · 629 replies / 84,899 views (as of 13 Oct 2026)
Our own explanation; forum threads are linked, not copied. Not investment advice.
More topics
- The Bitcoin puzzle transaction: why keys can't be guessed
- Bitcoin supply and inflation over time
- My Bitcoin transaction is stuck: RBF and CPFP explained
- Lost wallet password or seed: what can be recovered
- Bitcoin or gold? A plain comparison
- Satoshi Nakamoto and Hal Finney: the first Bitcoin transaction
- Bitcoin Pizza Day: 10,000 BTC for two pizzas
- History of Bitcoin hacks: why 'not your keys, not your coins'