Nassim Nicholas Taleb, the author, says: “The way people reveal, unconsciously, that an action is in their best interest, is by telling you it is in your best interest.” British eurosceptics are doing exactly this to Nick Clegg, the Liberal Democrat Deputy Prime Minister, and Ed Miliband, who leads the Labour opposition.

Both men are urged to match the Conservatives’ offer of a referendum on European Union (EU) membership after the next election — and to announce it as early as their party conferences this week and next. Both are told this gesture is not only right in principle, but certain to help them electorally. And both, for different reasons, will be fools to follow this apparently magnanimous counsel.

Withholding a referendum is risky, of course. It is a provocation to an electorate that has not had a direct say in the European question since 1975. It furnishes David Cameron, the Tory Prime Minister, with a unique selling point at the next election. And when the denial of choice comes from pro-European politicians in a eurosceptic country, it reeks of fear and hauteur. But a thorny position is worth holding if the alternative is even worse. For both men, it is.

As no party can be confident of outright victory in 2015, Clegg may again find himself haggling for a coalition with Cameron. In those negotiations, the Tories’ overriding demand will be Lib Dem acquiescence to their planned plebiscite. Now a quarter of a century into their eurosceptic monomania, Conservatives will not wear anything less. So Clegg can ask for almost anything he likes in return: A property tax, another go at electoral reform or a place for a Lib Dem minister atop one or more of the great offices of state. The moment he commits to a referendum before the election, he throws away the mightiest of bargaining chips.

For Miliband, who may actually be prime minister, there is even less reason to heed the eurosceptics. If he pledges a referendum for, say, 2017, the Tories’ preferred date, he will lose the first two years of his government to European arcana and the slog of the campaign. If Britons then vote to leave the EU against his advice — and an unpopular midterm prime minister is unlikely to sway sceptics — his premiership will be stone dead the day after. And all because of a fight he never really wanted to pick in the first place.

Eurosceptics are right to say there is nothing sacrosanct about the Tory schedule, which envisages two years of high diplomacy to loosen the terms of Britain’s EU membership before a popular vote on whether to stay in on the revised settlement.

However, the alternatives being touted are even worse for Miliband. Some want him to demand a straight in-out referendum before the next election, or just after. This will immediately make Cameron’s plan look wishy-washy in the eyes of his perpetually aggrieved and mutinous backbenchers. But as the referendum will be on the current terms on membership, which Britons do not much like, it will also improve the prospects of the out campaign. Any political game-playing can result in exactly the outcome Miliband wants to avoid: Brexit.

Although a referendum pledge is strategic folly for Clegg and Miliband, it is sometimes worth storing up trouble for a later date if the tactical gain is large enough. But there is no reason to believe it will be. Cameron’s referendum speech last January did nothing for him politically: His revival in the polls came with the economy’s own improvement months later. Even the bought goodwill of his MPs dissipated quickly; they rather predictably came back for more sops and assurances in May.

None of this is surprising. Ipsos Mori polls confirm that the electoral salience of the European issue has actually dwindled since the 1990s. It grips a minority of voters, many of whom will never contemplate supporting the Lib Dems or Labour anyway, and bores the rest. Conceding a referendum will not help either party decisively at the next election. Any benefit is likely to be marginal and indirect: They will not come across as snobs who think such a profound subject is beyond the masses’ ken, they will look less awkward and furtive when pressed on the subject by Cameron. These are useful things in an election campaign, but they are not worth the longer-term price. In any case, the more Clegg and Miliband seem to be only granting a referendum to help themselves, the less likely they are to achieve even that tawdry goal.

He does a dazzling job of pretending otherwise, but Cameron never wanted to commit to a referendum. It was extracted from him under duress by a party that has come to regard euroscepticism as its corporate mission. Clegg is under no such pressure. Neither, really, is Miliband — there are advocates of a referendum in his shadow cabinet, but none is zealous enough to force his hand.

The only good reason for either man to match Cameron’s offer is high principle. The EU is unrecognisable from 38 years ago and is about to mutate even more. It does not take a leering populist to think a referendum is overdue. The mistake is to believe it will be in either party’s political interests. That eurosceptics are telling them it is should be the clue.

— Financial Times