Quadratic Voting

Overview

Quadratic voting (QV) is a collective-decision mechanism in which each voter is given a budget of "voice credits" and may buy votes for or against a proposal at a quadratic price: buying n votes costs n² credits.[1] The mechanism was formalized by economist E. Glen Weyl (from an earlier 2012 working paper, "Quadratic Vote Buying") and developed with Steven Lalley in "Quadratic Voting: How Mechanism Design Can Radicalize Democracy" (2018); under stated assumptions the authors show QV is asymptotically efficient at aggregating preference intensity, not just preference direction, because the quadratic cost schedule is the one that makes a voter's optimal spending proportional to how much the outcome is worth to them.[1][2] QV is independent of land or rent capture — it is a governance mechanism, not a tax — but it entered Georgist-adjacent discussion through Radical Markets (2018) by Eric Posner and Glen Weyl, which paired it (Ch. 2) with the Georgist-inspired Harberger tax as a second application of the same mechanism-design philosophy — using price signals to reveal true preferences — to a different domain, voting rather than property.[2] Vitalik Buterin's endorsement of Radical Markets helped carry both proposals into cryptocurrency and mechanism-design circles, where QV variants (quadratic funding for public goods) have since been piloted.[3]

QV's link to Georgism is one of shared method and shared advocates, not of shared subject matter, and it sits further from the airtight land case than the Harberger tax does: it makes no claim about land, rent, or unearned value, and its efficiency result depends on assumptions — a well-defined "voice credit" budget, no vote-buying collusion or credit markets between voters — that are contested in the political-mechanism-design literature. Richard L. Hasen argues QV would in practice founder on collusion, wealth inequality in the effective value of credits, and the difficulty of a fixed budget in real elections;[4] Goodman and Porter show formally that QV yields optimal policy only under restrictive conditions and generally will not.[5]

See Also

• Radical Markets — the book that paired quadratic voting with the Harberger tax as sibling mechanism-design proposals
• Harberger Tax (COST) — the Georgist-adjacent proposal QV is most often discussed alongside
• Vitalik Buterin: On Radical Markets — the essay that carried both proposals into tech and crypto circles
• Posner & Weyl, Radical Markets (full book scan)

Sources

1. Steven P. Lalley & E. Glen Weyl (2018), "Quadratic Voting: How Mechanism Design Can Radicalize Democracy," AEA Papers and Proceedings, 108, pp. 33–37 — used for the mechanism's definition (n² cost) and the asymptotic-efficiency result (A-claim). SSRN working-paper version
2. Eric Posner & Glen Weyl (2018), Radical Markets: Uprooting Capitalism and Democracy for a Just Society, Princeton University Press, Ch. 2 — used for QV's pairing with the Harberger tax as a shared mechanism-design program (A-claim). Publisher page; see also wiki summary.
3. Vitalik Buterin (2018), "On Radical Markets." vitalik.eth.limo — used for the claim that this essay carried QV and the Harberger tax into crypto/tech circles; see also wiki summary.
4. Richard L. Hasen, "QV or Not QV? That Is the Question: Some Skepticism about Radical Egalitarian Voting Markets," The University of Chicago Law Review (Quadratic Voting symposium) — PDF. Used as the skeptical secondary source on QV's real-world assumptions: collusion, the unequal real value of credits under wealth inequality, and the fragility of a fixed voice-credit budget in actual elections.
5. John C. Goodman & Philip K. Porter, "Will quadratic voting produce optimal public policy?" Public Choice 186(1), 2021, pp. 141–148. DOI: 10.1007/s11127-019-00767-4 — used for the formal result that QV attains optimal policy only under restrictive conditions and generally will not.