First-past-the-post voting has been praised for promoting political stability by producing two-party or nearly two-party systems. Yet, as the outcome of the United Kingdom's recent election shows, that supposed benefit comes at the price of a government in which a minority can ride roughshod over the interests and preferences of more than half of the population.

On the most important issue in the United Kingdom’s modern history – whether to leave the European Union or remain – the UK’s electoral system produced an absurd result. A majority of the UK public wants to remain in the EU and actually voted accordingly in the parliamentary election on December 12. Yet the election produced a large majority for the Conservative Party, which backs a quick Brexit. The reason is as simple as it is troubling: the failure of the first-past-the-post electoral systems to translate public sentiment into reasonably representative outcomes.

In a first-past-the-post electoral system, each legislative seat goes to the candidate who wins the largest share of the vote, regardless of whether it is a majority. Thus, when the majority opinion is divided among several parties, the minority view prevails with a minority of votes.

As a simple illustration, suppose that there are three parties: Remain-1, Remain-2, and Leave. Suppose that in every district, 66% of the public wants to remain and 34% wants to leave, with the remain voters divided evenly between the two remaining parties. Remain-1 and Remain-2 each receive 33% of the vote in every district, while the Leave Party wins the district seat with 34%. If this result is replicated across all districts, the Leave Party wins 100% of the seats with 34% of the national vote. In a nationwide proportional-representation system, by contrast, the Remain parties would win 66% of the seats and would form the government.

Of course, the actual situation in the UK is more nuanced. Brexit was not the only campaign issue, and 11 parties, not just three, received at least 0.4% of the national vote. Of those 11 parties, eight – Labour, the Scottish National Party, the Liberal Democrats, Sinn Féin, Plaid Cymru, the Social Democratic and Labour Party, the Green Party, and Alliance (APNI) – campaigned either for a second Brexit referendum (a “people’s vote”) or for remaining in the EU. Three of the 11 parties campaigned for Brexit without a second referendum: the Conservatives, the Democratic Unionist Party, and the Brexit Party.

In total, the 11 parties received 98.6% of the vote, with dozens of smaller parties accounting for the remaining 1.4%. The eight parties campaigning to remain or hold a second referendum received 52.2% of the vote, while the three parties campaigning for Brexit with no second referendum received 46.4% of the vote. Yet, the three pro-Brexit parties took 373 seats, compared to just 277 seats for the parties seeking to remain or hold a second referendum.

There are two reasons for this outcome. First, the Brexit vote was nearly all concentrated in one party, the Conservatives, which received 94% of the combined Brexit vote. Labour, by contrast, won only 61% of the vote among the eight parties opposed to Brexit or calling for a second referendum. Prime Minister Boris Johnson united the Brexiteers. Labour’s leader, Jeremy Corbyn, splintered the Remainers.

The second reason is that, under first-past-the-post, the overwhelming majorities (70% or higher) secured by Remainers in some districts – for example, London and Scotland – amounted essentially to wasted votes; the party still won just one seat. In a proportional-representation system, those votes would count toward the party shares at the national level.

Last week’s vote shares were in line with recent public opinion surveys on Brexit. In a particularly telling poll, carried out just before the election, Remainers outnumbered Leavers, 53% to 47%. A majority of voters want to remain, yet the electoral system produced an overwhelming parliamentary majority for leave.

The UK is one of only a handful of high-income democracies – including the United States and Canada (as bequeathed by the UK) – with a first-past-the-post system. If the UK had a national proportional vote system, as almost all of continental Europe does, it would be heading for a second Brexit referendum and staying in the EU. The election results would probably have produced a multi-party coalition government against a quick Brexit.

Another glaring problem, less easily solved, is that young people overwhelmingly want to remain in the EU, while older people want to leave. Older voters are imposing a future on young people who do not want it, but who will most likely have to deal with the consequences for the rest of their lives.

First-past-the-post voting has been praised for promoting political stability by producing two-party or nearly two-party systems. Britain’s two main parties received 76% of the vote and will have 87% of the seats in the next Parliament. Yet the stability is illusory. It comes at the price of a government in which a minority can ride roughshod over the interests and preferences of more than half of the population. When that happens, society becomes politically polarized.

In continental Europe, most governments are multi-party coalitions. They can be difficult to form, cumbersome to maintain, and slow to act. Yet the very process of multi-party coalition-building prevents a minority from walking away with the political prize against the wishes of a large part of the population.

The situation is even more dangerous in the US, where presidential elections install a powerful executive who dominates a two-party legislature. This is a triply cursed system. First, the two parties do a poor job of representing public opinion, not least because of the plutocratic funding of US congressional campaigns. Second, excessive power is vested in the hands of a single individual. And third, because of the peculiarities of the Electoral College, the president can win with fewer votes than the opponent – as has occurred in two of the last five presidential elections. In 2016, Donald Trump won 57% of the electoral votes, despite receiving 2.8 million fewer votes than Hillary Clinton.

As I have written previously, and as the UK’s recent election confirms, the two main Anglo-Saxon democracies are failing. But they are failing not only because of a polarized electorate but also because of the first-past-the-post electoral system, which produces governments that do not represent public sentiment well.

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Jeffrey D. Sachs, Professor of Sustainable Development and Professor of Health Policy and Management at Columbia University, is Director of Columbia’s Center for Sustainable Development and the UN Sustainable Development Solutions Network. His books include The End of Poverty, Common Wealth, The Age of Sustainable Development, Building the New American Economy, and most recently, A New Foreign Policy: Beyond American Exceptionalism.

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