The UK newspaper The Times asked Prof. De Cremer to respond on the art of negotiation in Brexit by sending in a letter to the editor. Here is the link to the letter but you can also read it below.

Sir, Daniel Finkelstein is right in saying that the EU should tell the UK to go away and only come back when they know what they want. The simple truth of any negotiation is that it takes place when parties need each other to achieve their goals, but this requires a willingness to collaborate. The position of the EU is that it does not want the UK to leave, whereas the UK does not want to stay. Good negotiation theory says that to achieve cooperation one should negotiate based on interests and not positions. Positions polarize the negotiation process and avoid communication aimed at reconciling wants. The UK has failed in making clear what it wants because Theresa May failed to build a coalition back home before negotiating with the EU. The EU is as such facing an unprepared opponent who is not able to bring a coherent and constructive voice to the negotiation table. There can then only be one piece of advice: Go home, do your homework and clarify what you want. Donald Tusk already called for patience with the UK. So, what are we waiting for?