In the very limited sense that it is theoretically possible, Mr Cameron is right. But in practical terms, it is absurd to believe that the UK can steer the EU away from its founding objective of "ever closer union" and, therefore, that we are going to be able seek changes to our "relationship".
Thus does Booker write to tell us that the only solution to our "EU mess" is Article 50.
In all the brouhaha over a Euro-referendum unleashed in the wake of that surge in the polls by UKIP, he writes, it is hard to know who is talking the emptiest fluff. We really are paying the price for all those years when our politicians and media were so keen to bury our European system of government out of sight that they have little idea of the harsh realities of the situation in which we find ourselves.
We have Tory MPs piling in to demand an in-out referendum before 2015, which they are not going to get. We have former political heavyweights such as Lord Lawson, Denis Healey and Norman Lamont queuing up to say that if there were such a referendum they would vote to leave.
We've even got Nick Clegg and those poor little BBC presenters locked in a 13-year-old time warp, trying to tell us that, if we did leave, 3.5 million British jobs would vanish because our trade with our European neighbours would somehow dry up overnight.
None of this bears any more relation to where we actually are, as one of the 27 fully signed-up members of the EU, than David Cameron's threefold dollop of wishful thinking that, if only we re-elect him in 2015, and if only he can somehow persuade his EU colleagues to hand back a few unspecified powers of government –– in breach of the most basic principle on which the EU was founded – he can somehow lead the " yes" campaign in 2017 to a referendum vote for Britain to stay in.
It is true we may one day by law have to have a referendum, whichever party is in power, because sooner or later the drive to give Brussels even more powers in its efforts to save the doomed euro will require a new treaty.
But in the meantime Mr Cameron is terrified that, unless we stay in the EU, we will lose the right to trade freely with its single market. Lord Lawson, in his own muddled way, seems equally to think that, by leaving, we would indeed be excluded from the single market, but that this would be OK because it would somehow bring us "a positive economic advantage".
The truth is that there is only one way we can get what they, and most people, seem to want, but none of them, except occasionally Nigel Farage, ever mentions it – and even then he barely gives it any emphasis. The only way we can compel our EU partners to negotiate a new relationship which would still give us access to the single market is by invoking Article 50 of the Lisbon Treaty.
Only thus can we negotiate precisely the kind of relationship already enjoyed, in their different ways, by the two most prosperous countries in Europe, Norway and Switzerland, which trade as freely with the EU as we do, but without the rest of that political baggage that inspires such growing resentment not just in Britain, but in many other EU member states.
This, of course, catches out Mr Cameron, because Article 50 can only be invoked by a country announcing its wish to leave the EU. He flatly refuses to recognise that it is perfectly possible to continue trading freely with the EU without belonging to it.
Lord Lawson falls into the opposite trap by also imagining that leaving the EU means being excluded from the single market, although he seems to think this could be an advantage because we could somehow make up for it by increasing our trade with the rest of the world. But both these men, like countless others, are living in cloud-cuckoo land. They will not bring their thinking back to earth by looking hard-headedly at the rules of the game.
The only way we can now face up to the reality of the plight we are in is by putting Article 50 at the very centre of the national debate. It is the only way we can get the best of both worlds that so many people say they want.
Unless we do so, we are doomed to wander on in a fog of wishful thinking that can only continue to leave us with the worst of all worlds – ruled by a dysfunctional system of government that we increasingly resent, but refuse to understand, Booker says.
In the words of Lady Thatcher, which he has quoted before, from her book Statecraft, that we should ever have become absorbed into this "European superstate" will one day be seen as "a political error of the first magnitude".
If we really wish to remedy that error, the only practical way that can be brought about is by invoking Article 50.