You cannot exit something that no longer exists.
I'm in Paris this weekend covering the first round of French presidential elections, a historic contest which will have a profound impact on Europe and the world.
Tomorrow's first round of voting could result in a run-off between a far-left and a far-right candidate, both of whom are hostile to the European Union and have in the past called for France to leave the EU. The latest polls show a race that is anyone's game, and could result in any number of second round combinations across the political spectrum. It is an election like France has never seen, and nobody knows that tomorrow will bring.
A first round win for far-right nationalist Marine Le Pen and far-left communist Jean-Luc Mélenchon would send shock waves throughout the world. It would not only mean the collapse of the mainstream political infrastructure in France. It would put the future of Europe, and of Western liberal democracy as a whole, in terrifying doubt.
Commentators, particularly in the English-speaking world, have taken to calling the possibility of either Le Pen or Mélenchon taking France out of the EU as 'Frexit'. It's a play on the UK's 'Brexit' decision to leave the EU (which itself was a play on 'Grexit', the word created when Greece was possibly going to be kicked out of the EU - remember that?). The idea is that either of these two extremist candidates are likely to call a UK-style in-out referendum on France leaving the EU.
But the comparison is a foolish one. The United Kingdom has always had an arms-length relationship with the EU. It was not one of the six founding member states, joining a decade later in 1973 along with Denmark and Ireland. Although it is one of EU's three largest member states, the UK has never behaved like it. Brexit will be traumatic for both sides, but the EU can survive it. An EU without the UK is completely conceivable, and always has been.
The heart of Europe
France is a different story. It is the founding member state. The union was created at French impetus - and certainly never would have happened without French insistence. West Germany and Italy were obviously the junior partners at the time, and the importance of the low countries was reflected in their name.
The EU started out as a French-engineered project. As West Germany experienced its economic miracle and, later, reunification, the essential relationship of the union became the Franco-German engine. Today these two countries are at the core of the EU, and it is impossible to imagine the EU without them.
In short, there can be no EU without France.
To talk of a 'Frexit', in the same way people talked of potential exits for Greece and the UK, is therefor nonsense. If France were to decide to leave the EU, that is the end. There would be no EU to leave at that point.
Polls indicate that if either Le Pen or Mélenchon were to call an in-out referendum, the French would vote by a large majority to stay in the EU. But it almost doesn't matter, because an anti-EU French president in the Élysée would irrevocably destroy confidence in the union.
If Le Pen is elected, the European project is finished - referendum or no. The French may not have understood it, but they would have voted for the end of the European project by voting for her. The panic that would set in across the continent would snowball. It is possible that even by the time Le Pen called a referendum, the EU would already have effectively died.
Far-left and anti-EU
He is essentially promising the same thing that David Cameron promised in 2014, but for different reasons.
Such an approach, thinking that France can dictate to the EU the terms of its future, didn't work for the UK and there is no reason to think it should work now. Contrast this with the approach of Emmanuel Macron, who has promised to initiate a constitutional convention in the Autumn, after the German election, in which all of Europe would take part to reform the union and make it fit for purpose. Macron's plan is not accompanied by any threat to walk away from the union if he doesn't get his way.
Mélenchon has a list of demands that would never be accepted by his EU partners. He wants the euro to shift to being a "shared" currency rather than a "single" currency, and to suspend basic provisions of the EU single market.
Unlike Cameron, Mélenchon hasn't come up with his plan as a crude device to placate a subgroup of politicians. For him, this is ideological. He views the EU as a capitalist cabal that could never deliver the Socialist paradise he envisions for France.
There is no reason to believe his stance has softened. Even if it has, how will he square his years of EU-bashing with a refusal to call or referendum or renegotiate the European project? He will be trapped by his own past words, just as Cameron was.
A dishonest campaign
There is a reason Mélenchon, like Le Pen, is not keen to talk about this now. The French public sees the chaos and uncertainty that has befallen the UK as a result of the Brexit vote.
Both candidates know that a strong majority of French people do not want to leave the EU, and the idea of calling a referendum would be a vote loser in this election. So they have gone quiet on the issue during the campaign. Even though their plans are plain to see in their manifestos, they don't walk about it in their stump speeches.
They have also not been asked about their referendum plans in any significant way during the televised debates. I have been talking to voters here in Paris since I arrived Friday morning.
When I ask Mélenchon and Le Pen voters (the latter has been hard to find in Paris, but the city is full of the former) what they think about the potential of their vote to destroy the European Union, they have had no idea what I'm talking about. Mélenchon voters in particular have had no idea about his referendum plans.
And so tomorrow we may end up with a second-round runoff that will guarantee the destruction of the European Union and a collapse of Europe into chaos. Do people understand that this is what they're voting for?
The maddening thing is that all this could happen despite the fact that a large majority of Europeans support the European Union. Things are sliding out of control because many people do not understand the consequences of their vote.
Europeans are marching, blindfolded, toward their own destruction.