[Paper Review] Social Choice Around the Block: On the Computational Social Choice of Blockchain

Davide Grossi|arXiv (Cornell University)|Mar 15, 2022

Blockchain Technology Applications and Security4 citations

TL;DR

This paper argues that computational social choice (CC) provides essential theoretical foundations for designing fair, robust, and incentive-compatible blockchain consensus mechanisms. It identifies key challenges—fairness in randomized block selection, manipulation in voting-based consensus, and Sybil resistance in trust-based systems—showcasing how CC concepts can solve core blockchain design problems with principled, computationally grounded solutions.

ABSTRACT

One of the most innovative aspects of blockchain technology consists in the introduction of an incentive layer to regulate the behavior of distributed protocols. The designer of a blockchain system faces therefore issues that are akin to those relevant for the design of economic mechanisms, and faces them in a computational setting. From this perspective the present paper argues for the importance of computational social choice in blockchain research. It identifies a few challenges at the interface of the two fields that illustrate the strong potential for cross-fertilization between them.

Motivation & Objective

• To establish the relevance of computational social choice (CC) in addressing fundamental design challenges in blockchain systems.
• To identify key interface points between CC and blockchain, particularly in consensus mechanisms involving randomness, voting, and trust.
• To frame open problems in blockchain—such as fairness in block selection and Sybil resistance—as canonical problems in social choice theory.
• To advocate for cross-fertilization between CC and blockchain research by showing that CC offers formal tools to analyze and design incentive-compatible, decentralized protocols.
• To highlight underexplored research opportunities in trust mechanisms, lottery fairness, and manipulation resistance, grounded in CC principles.

Proposed method

• Analyzes existing blockchain consensus protocols (e.g., PoW, PoS, Ripple/Stellar-style trust networks) through the lens of social choice mechanisms.
• Maps blockchain mechanisms to classical CC concepts: lotteries (randomized selection), voting (consensus via node agreement), and trust systems (influence propagation).
• Applies fairness criteria from social choice (e.g., equal probability of selection) to evaluate randomized block selection in PoW and PoS.
• Examines manipulation risks in voting-based consensus, drawing parallels with strategic voting and control in social choice theory.
• Assesses trust mechanisms using false-name-proofness and power index theory to quantify node influence and Sybil resistance.
• Uses informal, conceptual modeling to frame blockchain challenges as CC problems, avoiding formal mathematics while preserving theoretical rigor.

Experimental results

Research questions

• RQ1 How can fairness in randomized block selection (e.g., in PoW or PoS) be formally defined and ensured using computational social choice principles?
• RQ2 To what extent can voting-based consensus in blockchains be manipulated, and how do existing CC results on strategyproofness apply?
• RQ3 Can trust-based consensus protocols be designed to be Sybil-resistant, and how can costly identities or power indices enforce false-name-proofness?
• RQ4 What structural properties must trust networks satisfy to ensure consensus safety and prevent forks, and how can these be formalized using CC tools?
• RQ5 How can influence in decentralized consensus be quantified and decentralized, especially when some nodes accumulate disproportionate voting power?

Key findings

• Randomized block selection in PoW and PoS can be evaluated for fairness using social choice criteria such as equal probability of selection, revealing potential imbalances in influence.
• Voting-based consensus in blockchains is vulnerable to manipulation, similar to classical voting systems, and CC offers tools to analyze and mitigate such strategic behavior.
• Trust-based consensus mechanisms, such as those in Ripple and Stellar, can be analyzed for Sybil resistance using the concept of false-name-proofness, with costly identities offering a path to robustness.
• Structural constraints on trust networks—such as requiring overlapping trust sets—are necessary to maintain consensus safety, and these can be formalized using graph-theoretic and power-index-based models.
• Power indices from social choice theory can be used to quantify node influence in trust-based systems, offering a way to assess decentralization and detect de facto centralization.
• The integration of CC principles into blockchain design enables a principled approach to balancing fairness, safety, and incentive compatibility in consensus protocols.