Adaptive Quorum Biasing

3 min readMar 5, 2022

Polkadot institutes a cutting-edge governance model designed to achieve a healthy network that adapts to its users’ needs. It is designed to enable rapid and representative community engagement by leveraging blockchain technology for transparency and accountability. The DOT token enables low-friction engagement in Polkadot and provides an innovative level of sophistication and participation in distributed global governance. Making upgrades to distributed protocols is an undertaking that traditionally requires massive coordination efforts, creating expensive overhead for enacting new features and making it difficult for changes to be adopted, regardless of how contentious a proposal may be. Evolvability is paramount to the long-term viability of any useful product and blockchains are no different. Being decentralized, there is no trivial means to determine how the network product should evolve over time: governance is critical to ensure orderly and schism-free evolution. Decentralized crypto-economic systems will become the new states of the internet world and governance is key in ensuring these crypto-economic systems’ resources work in its (and its stakeholders’) interests.

To mitigate the reality that turnout is never likely to be at 100%, Polkadot introduces Adaptive Quorum Biasing. Quorum has traditionally been defined as a minimum number of participants present for a vote to be considered valid, but issues have arisen over the last few centuries.

Quorum-busting has been used by minorities to delay or prevent a vote from occurring, and some historical figures have gone as far as to jump out of windows to prevent a quorum from being reached. Studies have also shown that strict quorums decrease voter participation. Another issue is how to determine the minimum number of votes required for a quorum to be reached, a decision itself that can be contentious, and how to reach a decision without a defined quorum?

Voting systems without quorums have explored ways of incentivizing participation by means of rewarding voters, or inversely, punishing citizens who do not vote. Research has shown that such mechanisms may lead to much higher voter turnout, but a disproportionate effect on increasing voter knowledge.

Polkadot’s Adaptive Quorum Biasing changes the supermajority required for a referendum to pass based on the percentage of voter turnout.

  • A positive turnout bias requires a heavy supermajority of aye votes to carry at low turnouts, but as turnout increases towards 100%, it becomes a simple majority-carries as above. We call this a “positive” turnout bias because the required margin of ayes increases as turnout increases.
  • A negative turnout bias requires a heavy supermajority of nay votes to reject at low turnouts, but as turnout increases towards 100%, it becomes a simple majority-carries as above. We call this a “negative” turnout bias because the required margin of nays increases as turnout increases.

When a proposal is unanimously voted in favor by the council, it benefits from using the negative bias. We assume that if the council proposes a referendum, then low turnout is less troublesome. Public referenda, however, must be agreed upon using the positive curve. This is done to mitigate attacks by malicious or ill-conceived proposals.

“If only 5% of token holders vote, then 82% of that 5% must vote yes in order for that vote to pass. This effectively solves the turnout problem, which is the major issue with #governance today. ~Ryan Zurrer(Web3 Foundation)




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