When David Cameron pledged to hold an in/out EU referendum in the next parliament, having long opposed one, the hope was that it would solve his Europe problem. Tory optimists predicted that the commitment would unite the party, end the seepage of votes to Ukip, and allow Cameron to focus on more salient issues such as the economy (the EU does not even make it into the top ten of voters' concerns).
It has not worked. A year and a half on from Cameron's pledge, a Conservative MP, Douglas Carswell, has defected to Ukip, protesting that Cameron cannot be trusted to deliver a referendum (this despite him having promised to resign as prime minister if he fails to do so), Ukip is still riding high in the polls at around 15 per cent, and the PM is again being forced to bang about Europe (with MPs now demanding that he declares his willingness to campaign for withdrawal).
The lesson many draw is that Cameron was foolish to even try and appease the anti-EU brigade. Rather than being sated by concessions from the Conservative leadership, they simply bank them and come back for more. Short of a unilateral nuclear strike on Brussels, nothing will satisfy them.
All of this is true, but it is far from clear that there was a better alternative available to Cameron. Had he refused to promise an EU referendum, he would likely have suffered earlier defections to Ukip and even have been deposed as Conservative leader. His party would be even more divided than it currently is and Nigel Farage would be able to grandstand as the only man prepared to allow voters to have their say on EU membership.
The reality is that the Tories' Europe wars will only be resolved when the public either vote for withdrawal in a referendum (giving the Better Off Outers what they want), or vote to stay (providing a democratic justification for Britain's continued membership). Since Cameron hopes to achieve the latter outcome, the best strategy is the one he has chosen: renegotiation followed by a referendum (the model that worked for Harold Wilson in 1975).
The logical alternative to a strategy of appeasement would have been one of aggression, and that is not a road that Cameron could have taken with any confidence.