The British Parliament has commenced debate over Brexit, the United Kingdom's divorce from the European Union. In keeping with the entire Brexit experience, the outcome of that discussion remains unknowable. Britain remains deeply divided about the wisdom of Brexit in general and the particulars of the deal that Prime Minister Theresa May has worked out with the EU. For all the uncertainty, one thing is clear: Failure to reach a deal with the EU, for whatever reason, would be a disaster for the U.K.

Ever since the U.K. voted narrowly for Brexit in 2016, the country has remained deeply divided and almost evenly split. Not surprisingly, that division has been reflected in the ruling Conservative Party. May has lost seven Cabinet members over Brexit negotiations, the most recent quitting at the beginning of the month. And while all those who resigned believe that the deal — still very much an outline — does not protect British interests, they do not agree on the appropriate remedy. Several ministers believe that a second referendum is the solution, an option that May has rejected and for which there is little legal basis (and it is unlikely that the EU would agree).

More revealing, the most hard-core Brexiters cannot articulate a deal that they prefer and has the slightest prospect of winning EU approval. Supporters of Brexit made incredible promises that had no basis in reality. They asserted that the U.K. could maintain all the positive features of association with the EU — the trade advantages — while reclaiming the pieces of sovereignty that they wished to protect (immigration in particular). The EU resoundingly rejected this a la carte approach and with good reason: If London could keep the bits of membership that it liked and reject those policies it did not, then the organization would unravel as all its members sought similar arrangements.