Gordon Brown broke his lengthy silence on the future of Scotland yesterday with a statement of the case for retaining the Union that was refreshingly forward-looking.

Until yesterday, the former Prime Minister's championing of Britishness was chiefly notable for its clumsiness: a call for a national holiday to celebrate our shared values was received equally coldly in every part of the UK while the claim that Paul Gascoigne's goal against Scotland in Euro '96 was one of his favourite football moments produced ridicule. Perhaps he had absorbed some of the ease with which our Scottish Olympians revelled in being simultaneously Scottish and British because, delivering the Donald Dewar lecture at the Edinburgh Book Festival yesterday, Mr Brown produced a series of principled arguments that carried the weight of conviction.

The Unionist parties launched the Better Together campaign, headed by Mr Brown's Labour colleague and fellow former Chancellor Alistair Darling, by emphasising the advantages of the shared institutions of the British Isles and the additional clout Scotland gained internationally by being part of the UK. Mr Brown carried the argument to the Nationalists' territory by highlighting the distinctive nature of the Scots' contribution to the Union, particularly in the ideas of community and justice. His premise was that these values, allied to English traditions of liberty and individualism, together forged a political, economic and social arrangement that was more progressive than the EU or US and that could provide a template for other multinational agreements. This returns the independence debate to first principles.

In challenging the Nationalists' claim to guardianship of Scotland's communitarian values, Mr Brown provided a passionate cross-party voice that has so far been missing from the No campaign. But he correctly identifies the need for the debate about Scotland's future to rise to a higher level on the substantive issues.

A conclusive answer to whether Scotland would be better or worse off if independent remains elusive because there are too many variable factors, from the price of oil to the fate of the euro. But concentration on numbers has obscured wider consideration of the long-term effects of a divergent fiscal policy on the wealth of individuals as well as the nation's economy. Mr Brown's assertion that varying rates of minimum pay, corporation tax and social security will start a race to the bottom under which "the good provider in one area would be undercut by the bad and the bad would be undercut by the worst" should reignite the debate that must be had on policy.

A hunger for a nuanced public discussion on independence that goes beyond party dogma has been apparent for some time. Mr Brown has provided a timely reminder of the need for political parties, civic organisations and individuals keen to take part in the great debate to encompass both first principles and substance. He acknowledged the Scottish tradition of the democratic intellect. If there is life yet in that concept, now is the time to start exercising it.