Pragmatic definition of consensus for light clients

The discussion begins with the theoretical application of Utreexo commitments in Bitcoin through a soft fork, which could potentially streamline proof work by allowing verifications to start from an effective checkpoint rather than the entire blockchain history. This method would notably reduce the time required for proofs since only the recent portion of the block history would need detailed verification.

However, the primary issue highlighted is the lack of immutable consensus rules within Bitcoin that a Zero-Knowledge (ZK) proving system necessitates. Currently, Bitcoin does not maintain a fixed protocol enforced universally, as evidenced by variations in the libbitcoinkernel versions used across the network. This variability leads to uncertainties regarding the enforcement of new and existing soft forks, raising concerns about the reliability of ZK proofs under such conditions.

Furthermore, the practical utility of ZK systems in the context of Bitcoin is questioned. While ZK proofs could effectively summarize the header chain of Bitcoin, the slow growth rate and small size of Bitcoin headers diminish the potential benefits. The narrative conveys skepticism toward the practicality of ZK proofs in environments where consensus is fluid and subject to changes influenced by human decisions both present and future. Thus, it implies that relying on ZK systems might be impractical for ensuring long-term value or security within the Bitcoin ecosystem, as these systems fail to adapt to the dynamic nature of human-based consensus.