Most experts who follow the Brexit negotiations think the Withdrawal Agreement (WA) will sketch in pretty loose terms what the final relationship between the UK and EU will be, although some EU politicians have indicated a reluctance to do this..A vague WA has been called a ‘Blind Brexit’ (ht Chris Grey). While a blind Brexit might help in May’s efforts to achieve an agreement and (maybe) to get parliamentary approval for it, it remains a very undemocratic way forward . Here is why.
Suppose there are only two types of Brexit possible: a No “not the end of the world” Deal or BINO (staying in the single market and customs union). All the polls suggest No Deal is not the will of the people, and its support is in any case dependent on a false view of its economic consequences. Equally it is difficult to understand why anyone would support BINO compared to EU membership, as the only major difference is that we no longer get a say on how the rules we have to obey are changed.
A result of keeping the WA vague about the final relationship is that this binary choice is not apparent to many voters. In particular the UK government is still peddling various halfway houses that the EU is very unlikely to agree to, but we will not know for sure that they will be rejected until after the WA. If we did know it before the WA the number of people who had changed their mind would be greater than it is now, which in turn might embolden parliament to call the whole thing off.
Thus we will leave under false pretenses, of exactly the kind that led to the narrow vote to Leave in the first place. When it does become clear that there are only these two choices, it will be too late to change our mind without new costs. Re-entry into the EU might require becoming part of the Eurozone for example. So we will could end up with BINO plus face saving details forever, and pretty well everyone (including No Deal advocates) will agree we are worse off than we were before.
A similar problem happens if parliament does not approve the WA and we end up with a second referendum. The logic of a second referendum is clear. In the first in 2016 the promises made about what leaving would mean were various and many were untrue. Now we know what leaving does involve it makes sense to ask the people once again. Except in any referendum held after the WA fails to be approved, we will not know what the final deal will be, and that will give May the chance to spin her deal in any way that gets votes. Rather than a referendum on a final deal, it will in fact be a second referendum with unicorns only slightly less outlandish than in the first referendum.
This is what I mean by a very undemocratic procedure. The fault lies first with David Cameron, who should never have agreed to a referendum where the type of Brexit was unspecified. It then lies with May, who initially prefered Brexit fantasy to reality and despite Chequers still panders to the Brexiters. Above all it is the fault of the Brexiters, who by going back on an agreement made in December wasted precious time so they had more chance of getting No Deal.
The EU cannot really be blamed for going along with a vague WA. They are quite happy with BINO, and it avoids a No Deal accident. For that reason they may feel it makes sense to help May. The alternative of insisting on a detailed WA on future trade is high stakes: it could end Brexit, but could lead to No Deal. It is not surprising that most EU politicians would take the less risky option.
It remains the case, nevertheless, that by allowing May to have a vague WA on trade they are assisting in the deception of UK voters and MPs, who will be leaving the EU without knowing what is going to take its place. I hope that is something the EU recognises if we do leave in March 2019 and subsequently want to return. I suspect, however, that this is a vain hope.
 It is also costly in economic terms, because it prolongs uncertainty about what future trade relationships will be. Some of the issues I describe here may also divide those who voted Remain over whether the WA should be passed in parliament or not.