For all his ebullient confidence in the House of Commons and his evident ease in the role of Prime Minister, it is increasingly difficult to discern in David Cameron a sense of purpose and vision. In these uncertain times, what are the driving forces – both intellectual and instinctive – that motivate our Prime Minister to get up in the morning and to lead his country? On what principles does he base his decision-making, beyond mere crisis management? This week Tim Montgomerie called for a new big message from Mr Cameron. Tim is right (as ever) but I'd go further and say that our Prime Minister needs not just a message but a very clear set of convictions. In the current global political and economic upheaval, any leader lacking a political compass can be left high and dry by events. Much Conservative discontent, both on the backbenches and in the right-wing press, flows from the feeling that perhaps David Cameron doesn't have much in the way of convictions and that in his swift rise to power he has never felt under any real necessity to work out his creed.

My fellow columnist Bruce Anderson believes that Mr Cameron shares John Major's beliefs, desiring 1950s social stability combined with 1980s economic dynamism. Even Bruce, however, one of David Cameron's biggest fans, cautions that such a philosophy is inadequate in the face of today's political and economic challenges. In the heady hours and days following the General Election, as Mr Cameron fashioned a kind of victory out of defeat, his overt purpose was to restore Britain's economic health, joining forces with the LibDems to administer the necessary medicine. This objective did not require the application of a political philosophy, only an adherence to a simple message: cut the deficit. The rest of the coalition agreement was down to political horse-trading; no-one ever really pretended that it amounted to a coherent whole. Indeed, how could it? Governing in coalition with a party whose modern orientation is somewhere to the left of Labour was never going to be a meeting of minds, only a compromise based on a shared desire for power. For a while, that was enough. The collective sense of relief at seeing the back of Gordon Brown, and having instead a Prime Minister who could strut the national and international stage with style and grace, provided David Cameron with a honeymoon period in his party and in the country at large. No creed was required; indeed it might have seemed in rather poor taste to be banging on about ideology.

Eighteen months later and the world is a different place. The style and grace largely remain; our Prime Minister is certainly no national embarrassment. His social skills enable him to navigate international summits with a a great deal more good humour and aplomb than his predecessor or indeed his tetchy European counterparts. But as he tacitly admitted to David Miliband in Parliament on Tuesday, international summitry is looking pretty vacuous in the wake of the G20. As the Eurozone fiddles, Rome burns. In Tuesday's Financial Times, Gideon Rachman warned that prolonged attempts to preserve the Euro could kill the European Union altogether, and that the idea of fiscal union is an “inherently implausible” solution to the escalating crisis. Yesterday, Martin Wolf took a similar line. When the FT's principal commentators tell its readers that time is up for the Euro, why is our Conservative Prime Minister still arguing that the Eurozone must pull together to save its currency? Is this not a blessed opportunity for David Cameron and George Osborne to point out that the Euro was not just a bad idea for Britain but was and still is a bad idea for everyone involved? Just as the UK values its sovereignty, so should we speak out for the sovereignty of Greece (and indeed Italy), if we are Conservatives who believe in self-governance, parliamentary democracy and the nation state.

Watching the Prime Minister speaking to the Parliamentary Liaison Committee a couple of days ago about the Big Society, I felt there was a flash of conviction, a sense of something heartfelt. Here, surely, was a man of principles, speaking of “the best way to run our country.” Not, as he put it, through “top-down solutions” and the “big state”, but through “devolving power to the lowest level.” Cynics might say that this is merely a well-honed message, or a way of dressing up spending cuts. But I think, for David Cameron, it is much more than that. With Edmund Burke, he is convinced that small institutions are preferable to statism; that government should enable, not disable, and that decisions should be taken as closely as possible to those most affected by them. It's a powerful creed, and one that should run through a Conservative Prime Minister like the words in a stick of rock. It should be his answer to the European crisis, giving him a clear raison d'etre for the repatriation of powers, the break-up of the doomed Eurozone and the return to self-determination. It is as fitting for the international stage as for our domestic education and welfare policies; it should also determine our planning policy and changes to our infrastructure. Going with the grain of human nature, with the little guy and against the powerful elite.

In common with many leading politicians and most public speakers, David Cameron is always more impressive when he speaks without a script, and from the heart. The Prime Minister's consummate yet wholly natural performance before the Liaison Committee showed him at his best. If he were to transfer that conviction-based clarity to his every utterance – and in particular to his response to the European crisis – then the Press, his party and indeed the country, would have much more confidence in his ability to lead us out of the present muddle.