TURKEY matters not just for its size, but also as a bellwether of the political forces shaping the world. For centuries it was the seat of a great empire. Today, as a frontier state, it must cope with the violence spewing out of war-ravaged Syria; it is a test case of whether democracy can be reconciled with political Islam; and it must navigate between Western liberalism and the authoritarian nationalism epitomised by Russia. In recent years under Recep Tayyip Erdogan, Turkey has gone backwards. This weekend it can begin to put that right.

On April 16th Turks will vote in a referendum over whether to abandon their parliamentary system for an executive presidency. A Yes is likely, but far from certain. There is nothing wrong with a strong president, but Turkey’s new constitution goes too far. The country would end up with a 21st-century sultan minimally curbed by parliament (see Briefing). A Yes would condemn Turkey to the elected dictatorship of President Erdogan. A No might just let Turks constrain him.

Authority figure

After Mr Erdogan came to power in 2003, he and his AK party did a lot that was good. Encouraged by the IMF, he tamed inflation and ushered in economic growth. Encouraged by the EU, he tackled the cabal of military officers and bureaucrats in the “deep state”, strengthened civil liberties and talked peace with the Kurds. He also spoke up for working-class religious conservatives, who had been locked out of power for decades.

But today Turkey is beset by problems. In the shadow of the Syrian civil war, jihadists and Kurdish militants are waging campaigns against the state. Last summer the army attempted a coup—probably organised by supporters of an American-based cleric, Fethullah Gulen, who had penetrated the bureaucracy, judiciary and army in their tens of thousands. The economy, once a strength, is growing slowly, plagued by cronyism, poor management and a collapse in tourism.

Mr Erdogan argues that, to put this right, Turkey needs a new constitution that will generate political stability. He says that only a strong president can galvanise the state and see off its enemies. Naturally, he is talking about himself.

The new constitution embodies the “illiberal democracy” of nationalists such as Viktor Orban of Hungary and Vladimir Putin of Russia, to whom Mr Erdogan is increasingly compared. On this view, election winners take all, constraints are obstacles to strong government and the ruling party has a right to subvert institutions, such as the judiciary and the press.

Yet this kind of stability is hollow. The most successful democracies make a point of separating powers and slowing governments down. The guiding idea of the American constitution is to stop presidents from acting as if they were monarchs, by building in checks and balances. Even the British prime minister, untrammelled by a written constitution, has to submit herself to the courts, a merciless press and a weekly grilling in Parliament, broadcast live.

Turkey is especially ill-suited to winner-takes-all government. It is divided between secular, religious and nationalist citizens, as well as Turks, Kurds, Alevis and a few remaining Greeks, Armenians and Jews. If the religious-conservative near-majority try to shut out everyone else, just as they were once shut out, Turkey will never be stable.

But the most important argument against majoritarian politics is Mr Erdogan himself. Since the failed coup, he has been governing under a state of emergency that demonstrates how cruelly power can be abused.

The state is entitled to protect its citizens, especially in the face of political violence. But Mr Erdogan has gone far beyond what is reasonable. Roughly 50,000 people have been arrested; 100,000 more have been sacked. Only a fraction of them were involved in the coup. Anyone Mr Erdogan sees as a threat is vulnerable: ordinary folk who went to a Gulenist school or saved with a Gulenist bank; academics, journalists and politicians who betray any sympathy for the Kurdish cause; anybody, including children, who mocks the president on social media. Whatever the result on April 16th, Mr Erdogan will remain in charge, free to use—and abuse—his emergency powers.

During the campaign he accused the Germans and Dutch of “Nazi practices” for stopping his ministers from pitching for expatriate votes. EU voices want to suspend accession talks—which, in any case, are moribund. Before long, the talk may even turn to sanctions. Some in the West will point to Turkey’s experience to claim that Islam and democracy cannot coexist. But to give up on that idea would be to give up on Turkey itself.

The fault is not so much with political Islam—many AK members and voters are uneasy with the new constitution. It is with Mr Erdogan and his inner circle. Although he is a religious man, he is better seen as an old-fashioned authoritarian than as a new-fangled Islamist. The distinction matters because AK, or an Islamist party like it, is bound to feature in Turkey’s democracy. Mr Erdogan, however, will one day leave the stage, taking his authoritarian instincts with him.

Hold him close

Hence the outside world should not give up on Turkey, but be patient. Partly, this is self-interest. As a NATO member and a regional power, Turkey is too important to cut adrift. It will play a vital part in any peace in Syria. Driving it into Russia’s arms makes no sense. Turkey has also been a conduit for refugees into the EU as well as vital in controlling their inflow. The refugee situation is in flux: the EU will need to keep talking to Turkey about how to cope with the resulting instability.

Engagement is also in Turkey’s interests. The EU is its biggest trading partner. Contact with it bolsters the Western-leaning Turks who are likely to be Mr Erdogan’s most potent opposition. NATO membership can moderate the next generation of officers in its armed forces. Although Turkey will not join the EU for many years, if ever, a looser EU, with several classes of member or associate country, might one day find room for it.

Turkey will remain pivotal after April 16th. If Mr Erdogan loses, Turkey will be a difficult ally with a difficult future. But if he wins, he will be able to govern as an elected dictator.