So far the process of Brexit has focused exclusively on the needs and wishes of the UK and has not considered what could be economically, socially or, critically, politically acceptable to other Member States.
There is also a tendency by leading members of the Government to talk openly about what they want to see delivered by Brexit. If these cases are intellectually incoherent then that simply diminishes the negotiating position.
All the time that Mrs May is perceived as being unable to hold together a Cabinet, the more robust the Member States will be.
Too many versions of Brexit will spoil the potential deal.
Boris Johnson is offering Britain a vision of life outside the EU that is "intellectually impossible", a leading European finance minister has said.The foreign secretary reportedly told a Czech paper the UK was likely to leave the EU customs union post-Brexit - but still wanted to trade freely after.However, Jeroen Dijsselbloem, the Dutch finance minister, said such an option "doesn't exist" and was "impossible".Number 10 said a decision on membership of the customs union had not been made.