The Duverger Syndrome is democracies' most critical illness. Both the causes and the fixes are known. Solutions must be applied as a matter of priority.
Single Choice Voting produces divisive dualism as its primary observable consequence: two hostile camps where a full spectrum of political opinion existed before. From that binary landscape, a second consequence emerges. Once the camps exist, political actors discover what the terrain makes available: the issues that fracture the opposing coalition, which can be driven to the surface, kept permanently unresolved, and deployed as standard tools of electoral warfare.
A wedge issue is a political topic deliberately used to fracture the opposing camp, mobilise one's own base, and crowd out substantive debate. The key distinction: false dichotomies are the structural artifact of binary politics — the terrain. Wedge issues are the deliberate tactical exploitation of that terrain by political actors.
Not every controversial issue is a wedge issue. An issue becomes a wedge when it splits the opponent's coalition, energises one's own base through strong emotional reaction, and is resistant to compromise — framed as a binary moral question where any middle position looks like capitulation. The most effective wedge issues share one further property: they are more valuable as permanent campaign weapons than as resolved problems.
Where single-choice voting allows multiple parties to compete, a controversial issue can produce a new formation that represents it directly. Anti-immigration sentiment and environmental concern have each generated new parties in countries where that is structurally possible. But the appearance of a new party does not resolve the issue. Germany's immigration debate is no more settled for having a dedicated anti-immigration party in parliament. Climate policy remains contested despite decades of Green parties in coalition governments. New parties change who holds the weapon; they do not put it down.
Under strict plurality voting — the harshest form of single-choice voting — even this partial outlet is closed. A new formation cannot gain traction: the wasted-vote dynamic ensures that supporting it only damages the coalition closest to one's own views. The controversial issue is trapped inside whichever existing coalition is divided on it, where it festers. The opposing party discovers the fault line and exploits it.
The missing ingredient is not more parties — it is a different kind of candidate. Informed Score Voting makes possible what single-choice systems cannot produce: a candidate who offers a genuine synthesis across all the major wedge issues — sensible on immigration, credible on the economy, serious on the environment — and who deeply disappoints no one while satisfying enough of everyone to build a broad coalition. Under any single-choice system, that candidate cannot win. Under Informed Score Voting, they can.
This is why the United States has been arguing about abortion, gun control, and immigration for decades without resolution. These issues are more valuable as permanent campaign weapons than as solved problems. Resolution would eliminate the weapon. Neither side has an incentive to put it down.
The mechanism follows a predictable sequence:
The American experience is the richest laboratory for wedge issue politics, and the most consequential for global democracy.
Race and the Southern Strategy. The most consequential wedge realignment in modern political history. In the 1960s and 1970s, Republicans under Nixon and Reagan exploited white backlash to civil rights legislation to split the Democratic coalition of Southern whites and Black voters. The South transformed from solidly Democratic — as it had been since Reconstruction — to solidly Republican. The issue was not resolved; it was redirected into coded language about crime, welfare, and states' rights, where it has remained a structural element of American politics ever since.
Abortion. The paradigm wedge issue of the late 20th century. Following Roe v. Wade (1973), single-issue anti-abortion voters became a reliable Republican constituency, and the issue provided a permanent mobilisation mechanism that bound evangelical Christians to a party that had not historically been their political home. Democrats were split between progressive absolutists and Catholic or moderate voters uncomfortable with late-term procedures. Both parties benefited from keeping the issue alive and unresolved. When the Supreme Court's Dobbs decision (2022) overturned Roe, it scrambled the dynamic — Republicans suddenly had to own the real-world consequences of a position they had held as a mobilisation tool for fifty years.
Immigration. Exploited by both parties simultaneously, in opposite directions. Republicans use immigration to mobilise nativist sentiment and split the pro-business and pro-labour wings of the Democratic coalition. Democrats use immigration to mobilise minority voters and paint Republicans as nativist. Neither party has resolved the issue in decades of unified government control, because a resolved immigration system is worth nothing at the ballot box.
"Woke" culture and DEI. The contemporary omnibus wedge: an intentionally vague cluster of issues around race, gender, education curricula, and corporate diversity policies. Vague enough to mean whatever the voter most fears. Effective at splitting the Democratic coalition between white working-class voters and progressive activists, while unifying the Republican base under a common cultural grievance.
Independence versus unification. The foundational wedge of Taiwanese politics — the issue that structures every election and makes every other issue secondary. The DPP uses independence rhetoric to mobilise the Taiwanese-identity base; the KMT uses "stability" and "peace" to attract voters who fear PRC retaliation. Neither camp's actual governing policy differs dramatically from the ambiguous status quo — but the rhetorical framing maximises division, and both parties benefit from the ambiguity.
228 memory and transitional justice. The 1947 massacre and the White Terror remain actively contested ground. The DPP uses 228 commemorations to remind voters of the KMT's authoritarian history; the KMT accuses the DPP of weaponising historical wounds for partisan gain. The exploitation of shared historical trauma is a particularly corrosive form of wedge politics — it prevents genuine collective reckoning and turns grief into electoral ammunition.
Cross-strait relations and the PRC threat. The DPP frames every election as a choice between democracy and annexation, casting the KMT as complicit with Beijing. The KMT frames every DPP policy as reckless provocation that endangers peace. The underlying threat from the PRC is real and serious — but its electoral framing is systematically weaponised, making calm strategic debate nearly impossible to sustain.
Brexit — the United Kingdom. The ultimate wedge issue: one that not only split the opposing coalition but realigned British politics on an entirely new axis. European integration had divided the Conservative party for three decades; UKIP exploited that internal wound to force a referendum. Leave versus Remain cut across the old left-right divide, producing a new political geography that neither major party could manage cleanly. Brexit is the rare case where a wedge issue, once detonated, destroyed the terrain itself.
Immigration and Islam — France. The National Rally has used immigration and cultural identity to split the French left between universalist secularists and multicultural progressives, and to force the centre-right into a permanent competition for the same nativist ground. The issue drives Marine Le Pen to the second round of the presidential election in 2017 and 2022 — not because a majority of French voters want her policies, but because the binary of the second round forces a choice between her and whoever remains.
LGBT rights — Poland. The Law and Justice party's campaign around "LGBT-free zones" before the 2019 election was a textbook application: mobilise the rural Catholic base, split the urban-rural opposition coalition, and frame the issue as a defence of traditional values rather than as discrimination. The tactic worked electorally; it also produced real harm to the people it targeted.
Wedge issues share a structural feature that explains their longevity: resolution eliminates them as weapons. A settled issue cannot mobilise voters. A compromise defuses the emotional charge. Neither side has a rational incentive to put the weapon down — and several structural forces actively work to keep it loaded.
The binary prevents compromise. In a two-party system, compromise looks like weakness. Each camp is rewarded for absolutism by its primary voters. A politician who reaches across the aisle on a wedge issue risks being outflanked from within their own coalition — challenged in the primary, denounced as a traitor to the cause. The very same structural pressure that created the wedge prevents anyone from disarming it.
Identity entrenchment. Over time, positions on wedge issues stop being policy preferences and become identity markers. "Pro-life" or "pro-choice" is not just a view about abortion — it is who you are. Changing position feels like betraying one's community. The issue is no longer politically functional; it has become existential.
Aligned incentives. Media coverage rewards conflict — a resolved issue is boring, a live wedge generates attention. Single-issue advocacy organisations on both sides raise money by keeping the issue alive. Party strategists know which issues drive turnout and guard them accordingly. The entire political economy of a two-party system conspires to preserve the issues that are most corrosive to democratic health.
The permanent state of wedge warfare has a further consequence beyond polarisation. When political combat is rewarded over governance, when a party's rational strategy is to wound the opponent rather than to represent the voter, the pool of people willing to enter politics narrows and distorts. The good candidates step back. Which brings us to the third symptom of the Duverger Syndrome: the Good Candidate Drought.