Last week the EU and UK published a draft divorce agreement. Nearly two-and-a-half years after the UK shocked their own government by voting to leave the EU, we are about to discover what Brexit actually means.

Ofcourse the deal still has to be agreed by the EU and, harder still, by  UK Parliament. Several ministers, including the Brexit secretary, resigned in protest; Theresa May could yet be toppled. MPs must now grapple with multiple loyalties: to their constituents, their parties and their own beliefs, all of which are likely to have shifted since the referendum. Within weeks they will have to make the biggest decision facing Britain, and one of the biggest for Europe, in generations.

If the country has learned anything since 2016, it is to look before it leaps. Yet, in what well summed up the level of debate on Brexit, both hardline Leavers and Remainers alike trashed the deal before they had read a word of it. This makes no sense.

The terms of the divorce will take time for MPs and those they represent to digest—and they may well be amended by European leaders before Parliament has its vote. Nor is it clear what would happen in the event that the deal were voted down: more negotiating, a second referendum or crashing out without a deal? But as the crunch vote nears, mps must consider how to approach this fateful question.

First, we have to forget the past. The cheating that went on during the campaign, the premature triggering of Article 50 and the thin preparations are maddening. But they are questions for the inquiry that will surely one day dissect this national fiasco.

The task before Parliament is to decide in a cool-headed way whether adopting the terms on offer is better for the country than rejecting them.

Those who backed Remain—a group that includes most MPs—will find little in the deal to make them think they were wrong. Although it legally sets out only a temporary framework, its terms are clearly worse than the status quo.

Yet if they are to respect the referendum, MPs need also to judge the deal against what voters were promised during the referendum.

The Leave campaign had no formal manifesto, and most of those behind it have since fled the government but the animating idea was to “take back control”. In some ways the deal does this, notably in immigration, where Britain would reclaim the right to limit migration from Europe. The price of this is being kicked out of the single market, which would hit the economy. MPs must decide whether the government is right that the public accepts this trade-off.

But in other ways the UK will unequivocally forfeit control. It will stay aligned with many of the single market’s current and future rules, to keep trade flowing and the Irish border open, something the  EU has made a condition of any deal.

Once outside the EU, the UK  will have no say in setting these rules. European judges will still arbitrate on such matters, even though the UK will no longer be able to nominate them. This is not taking back control but giving it up.

Meanwhile, as long as it remains in a customs union Britain will not even get the consolation prize of signing trade deals with other countries, something by which many Brexiteers have come to set enormous (and unwarranted) store.

The deal also has implications for the integrity of the United Kingdom. It would keep open the Irish border, but create a deeper regulatory divide between Northern Ireland and mainland Britain. Whilst most English voters do not care much about Northern Ireland, MPs, particularly those from what is formally called the Conservative and Unionist Party, should ask themselves whether it is right that an accidental by-product of Brexit should be a step towards Irish unification.

Hanging over this debate about the pros and cons of the deal is the question of what overturning it would do to the health of Britain’s democracy. Parliament has the legal right to ignore the referendum. But after a record number of people voted (to “take back control”, no less), it could be catastrophic for trust in mainstream parties if it were to do so.

The democratic argument is complicated. The vote to leave was an expression not just of Euroscepticism but of a wider frustration. It exposed divisions by age, region and class that the old left-right party divide had covered up. Far from bridging those divides, the bitter arguments since the referendum have if anything caused the two sides to move even further apart.

Overturning the vote would risk making them irreconcilable but adopting a Brexit deal like the one on offer would be unlikely to heal those wounds. Indeed, if the referendum was a howl by the left-behind against rule by remote and uncaring elites, this form of Brexit could make those problems worse. Anger at unaccountable rulers would not be assuaged by a deal in which Britain followed orders from people it could not elect. And those keen just to get the whole thing over with might find that Brexit marked only the beginning of national argument about the relationship with the behemoth next door.

Nor is it clear that the democratic thing to do is to hold people to the result of a two-year-old, narrowly won referendum, when the consequence of the vote has turned out to be quite different from what many voters expected. Polls suggest that a small majority now prefers Remain to Leave; more might prefer Remain to a compromise like the deal on offer. Almost all MPs want to respect the will of the people. The question is whether the people’s will found its perfect and enduring expression in 2016, or whether it might have changed.

There is no simple way out of this endgame. Whether the Brexit deal is accepted or rejected, it will scar Britain for years. Too many politicians are still grandstanding. Some Brexiteers still pretend there is a Planb that would deliver a painless exit.

Labour is mainly concerned with forcing a general election.

That needs to change, and fast. This decision must be made in the most reasoned way possible and with the maximum information available. Politicians of all stripes have spent the past two years talking about the national interest. In the coming weeks they must weigh up where they think it lies.