For the second time in as many months, George Osborne, the Shadow Chancellor, finds himself politically in choppy waters. The first time resulted from his having dallied too long this summer on the yacht of the Russian oligarch Oleg Deripaska in Corfu. The second time came this weekend, when he fell under scrutiny for challenging the responsibility of the Government's plan to revive Britain's economy through tax cuts. Mr Osborne argues that the future burden of paying for such cuts might so fracture faith in Britain's ability to meet its debts that they risk corroding further the already tarnished value of sterling.

You might disagree with Mr Osborne's alternative prescription - that tax cuts which are not funded by cost savings elsewhere would recklessly endanger an already enfeebled economy still further. You might argue that desperate times call for desperate measures; that we are embarking on an economic journey without maps and that, in such circumstances, the old signposts must be ignored in favour of a pragmatic, live-now-pay-later response.

But it is surely wrong to quibble with Mr Osborne's contention that, while it not the obligation of an Opposition always to oppose, it is its prerogative, even its duty, to do so when it feels the Government is behaving rashly (see page 19). Leave aside the fact that accusing Mr Osborne of talking down the pound sounds rich when sterling has already lost a quarter of its value against the dollar since the summer, and stands at an all-time low against the euro. The attempts this weekend by the Prime Minister and his Chancellor to portray Mr Osborne as, at best, a wartime blabbermouth whose loose lips risk sinking our economic ship and, at worst, some kind of unpatriotic subversive out to wreck Britannia, smack more of the Russian Duma than of open debate.

“My job as Shadow Chancellor,” Mr Osborne said yesterday, “is to tell the British people the truth about the British economy,” adding that: “David Cameron and I are deadly serious about fiscal responsibility.” Of course, everyone is deadly serious about fiscal responsibility. But, like beauty, fiscal responsibility sometimes turns out to be in the eye of the beholder. It can mean different things to different people. Mr Brown says that the case for unfunded tax cuts is unanswerable. It is answerable: it is just that Mr Brown doesn't care for those particular answers.

Should we be borrowing heavily now, sharing Alice's call for jam today, and not concerning ourselves too strenuously with what we'll spread on our toast tomorrow? Or should we only enact tax cuts that are funded by savings elsewhere - a strategy championed by the Conservatives, but spurned by the Government as offering no stimulus at all, on account of its being self-balancing.

This newspaper leans towards the strain of fiscal caution framed by Mr Osborne. Yet we also welcome debate. Anyone today must be humble enough to acknowledge that shepherding the economy through the most disorienting crisis in half a century is as precarious as steering a tanker through fog. It would be hubristic to be stubbornly confident about any fiscal prescription, given how many one-time certainties have proved to be as reliable as those SatNavs which lead overtrusting drivers straight into a lake.

For Gordon Brown to accuse Mr Osborne of playing politics with sterling insults not only Mr Osborne, but also a public striving to make sense of the economic chaos. It echoed the way he accused Mr Cameron last week of playing politics with the Baby P tragedy. The Prime Minister cannot hide under the skirts of the “national interest” to quash reasonable concerns about the economy and social care. He should focus on steering his course for the economy, rather than telling the Opposition it is not allowed to oppose.