Will Britain follow through on the vote to actually leave the European Union? Britain’s ubiquitous betting markets didn’t have it right when they predicted voters would reject the proposal to leave the EU in a national referendum last week. But give them credit for asking the right question in the aftermath, namely whether Britain will actually go through with a Brexit by invoking the essential Article 50 of the Lisbon Treaty.

The nascent market on Brexit at the Betfair exchange puts even odds on whether this will come to pass. “It’s been a very bizarre week, to say the least,” said Naomi Totten, a spokeswoman for Betfair. But in these uncertain times, punters can find lots of signs that a vote by a simple majority won’t be enough for Britain to make good on the momentous decision to abandon 43 years of EU membership. In any case, when U.S. Secretary of State John Kerry has the temerity to suggest the Brexit decision could be “walked back,” the question bears answering.

Here are four reasons why Britain might avoid a Brexit.

1. There is no majority in Parliament for Brexit, nor was the referendum legally binding. These facts were obvious before the referendum; now they are essential. Disengaging from the EU will require legislation, most notably a law repealing the laws that Britain passed when it originally joined the EU.

The House of Commons is perhaps three-quarters pro-EU. Anyone who argues that the referendum binds members in a political sense is asking those who oppose Brexit to either vote against their conscience or resign. How likely are either of those outcomes? Consider: There are signs, like a poll released this week, that over 1 million Britons already regret voting to leave the EU. And if members of Parliament are asked to vote on legislation abandoning the EU, they will do it against the backdrop of the near-certainty that they are breaking up the United Kingdom, since Scotland is likely to seek independence.

2. Only Parliament can trigger Article 50. There’s no precedent for this situation, but start with the basics: Parliament is sovereign in the United Kingdom, and membership in the EU has conferred all sorts of rights (human rights, defensible through European institutions) and privileges (payments to British farmers under the Common Agricultural Policy) on British subjects. If Article 50 is invoked, Britain is out in two years, whether or not it negotiates a replacement relationship with the rest of the EU, and those rights disappear.

A group of British attorneys affiliated with the UK Constitutional Law Association have made the case that no government can set that process in motion. “Brexit is the most important decision that has faced the United Kingdom in a generation and it has massive constitutional and economic ramifications,” they wrote in their brief. “In our constitution, Parliament gets to make this decision, not the Prime Minister.” At the very least, this issue will be fought out in court.

3. Brexiteers don’t have a viable negotiating stance. Wanting to leave the EU isn’t enough; advocates need a positive agenda for what kind of relationship they do want afterward, but it involves squaring a circle. Nigel Farage and other members of the U.K. Independence Party ran a campaign against immigration to Britain while simultaneously urging continued membership in the European Single Market. Well, the Single Market includes freedom of movement, as other European leaders are now helpfully pointing out, and they are going to insist on it if Britain wants the Single Market.

Cecilia Malmstrom, the EU’s trade commissioner, put it pretty clearly today: “Out is out. They can’t be half in.” In other words, British Brexit proponents now face the daunting task of negotiating with an angry EU while keeping the open-to-commerce-but-closed-to-migrants promises they made during the campaign. If they fail, they anger their own domestic constituencies. Do they have the guts to even try?

4. The public will feel the British economy contract. The only debate about the impact of the vote on Britain’s economy is how bad it will be. Unemployment is expected to rise, and that will affect public opinion and produce more regretful “leave” voters. Almost three-quarters of the respondents to a Bloomberg News survey of economists predicted Britain will slip into a recession, with the only divide between them being whether it will be this year or 2017. Mark Carney, the governor of the Bank of England, warned that a vote for Brexit would tip the country into recession.

Only a Parliament that favors EU membership can trigger the start of the Brexit negotiating process. The opponents of EU membership don’t even have a coherent position. And the economic fallout will sour the public mood with every passing day.

A recipe for Brexit? Not so fast.