At the heart of the British referendum is a fundamental paradox. Prime Minister David Cameron campaigned for reform in the European Union, and when he got most of what he wanted, backed the campaign to stay. If, however, his compatriots vote for leaving, the reforms will be irrelevant to Britain, which will suddenly be looking for a new modus vivendi with its former partners. Britain will not only lose its ability to influence developments but will also be a catalyst for further change in the bloc. Whether this will be toward further union or fragmentation, Britain will be powerless to act — like being in the trunk of Mr. Gove’s proverbial car.

The argument that Britain can do better on its own seems to be based on nostalgia for a time when it was a great power. In Greece, though, we remember how, at the height of our civil war in early 1947, an exhausted Britain handed the Greek problem to the United States — leading to the Truman Doctrine, confirming American dominance in the region. Within two decades, all but a couple of outposts of Britain’s empire had been abandoned.

President Barack Obama, visiting London on Friday, referred to the “special relationship” between his country and Britain, adding, however, that Britain would be stronger by remaining in the European Union.

The analysis by Mr. Cameron’s government says that annual economic output would be £4,300 (about $6,100) lower per household if Britain left the bloc. The governor of the Bank of England, Mark Carney, fears that Britain could lose its status as a pre-eminent financial center. Mr. Gove argued that Britons could hedge their bets — voting to leave but taking their time to do so. “We can set the pace,” he said. “After we establish full legal independence we can then decide which E.U.-inspired rules and regulations we want to keep ... while we calmly take our time to change the law, one thing which won’t change is our ability to trade freely with Europe.”

Last summer, Greece’s government had a similar win-win idea: hold a referendum and campaign against a new bailout agreement with creditors, but stay in the eurozone. However, when creditors made it clear to Prime Minister Alexis Tsipras that he had no alternative but to lead his country into the wilderness, he signed on to the deal. Mr. Tsipras — like Brexit campaigners — had ignored the observation on Britain’s great gift to the world, attributed to Jean-Paul Sartre : “In football everything is complicated by the presence of the opposite team.”