Buterin Walks Back 2017 View as ZK Proofs Enable Verification

• Vitalik Buterin reversed his 2017 view on full user verification.
• ZK-SNARKs now allow full chain correctness checks without replaying all transactions.
• Buterin said failures like censorship, outages, and validator concentration changed his views.

Ethereum co-founder Vitalik Buterin said he no longer agrees with a June 9, 2017, post where he dismissed the idea of regular users verifying the full blockchain history.

That comment came during a debate over whether blockchains should store only transaction order or also commit the full system state, such as balances and smart contract data.

At the time, Buterin opposed designs where users could only rebuild the state by replaying every transaction or by trusting third parties.

Ethereum chose to commit state roots directly into block headers, which allows any user to prove a balance or contract value through a Merkle proof. This design relies on an honest majority of validators, not a single service provider.

Buterin said that the model was always better than trusting one RPC endpoint, but still failed to give users a true fallback when systems break.

ZK Proofs Change the Cost Equation

The main shift came from zero-knowledge proofs. According to Buterin, ZK-SNARKs now allow users to verify the correctness of the chain without re-running every transaction since genesis. This removes the old tradeoff between trust and computation cost.

In simple terms, users can now check that the full chain state is correct using compact proofs instead of raw execution. That makes full verification practical again without forcing block sizes so small that the network becomes unusable.

Buterin described this as a direct answer to debates from the block size wars, with remaining limits tied mainly to data bandwidth and block production centralization.

With this tool available, he said, design compromises made in earlier years no longer hold.

Failure Modes Matter More Than Theory

Buterin also said his thinking changed due to real-world failures, such as P2P failures, latency spikes, service provider shutdowns, and concentration of validator sets. He added that censorship appears, as seen during the Tornado Cash restrictions.

In those cases, telling users to rely on developers becomes a form of central control. When the only fix requires deep technical work, many users lose access to funds or exit the system entirely.

Buterin said blockchains meant to last decades must offer a last-resort option where users can operate independently if everything else fails. He described full verification as a safety cabin, not a daily lifestyle. Its value comes from always being available.

The knowledge that users can fall back to it also forces intermediaries to behave better, similar to how BitTorrent keeps pressure on media platforms.

Related: Vitalik Buterin Defends Shift to Privacy-Focused Tools Following Community Criticism