The phone-hacking scandal has put investigative journalism in the dock. Yet without investigative journalism - and in particular the meticulous work of one investigative journalist, Nick Davies, of the Guardian - it's a scandal that would have never seen the light of day.
Right now it's the journalistic and moral failures, and the human consequences of those failures, that loom large. But don't lose sight of the second half of the paradox when you consider how British journalism should respond to the events at the News of the World.
A few days ago John Witherow, the editor of the Sunday Times, launched what was, under the circumstances, a brave defence of investigative journalism. He claimed that, at its best and when directed in the public interest, investigative journalism and its ability to uncover wrongdoing and deceit can be a powerful force for good. He acknowledged that achieving that good can sometimes mean breaking the rules. And he worried that the understandable political and public backlash against phone hacking at the News of the World might make the best kind of investigative journalism more difficult to conduct.
I believe he's right. Had it not been for the Sunday Times and the separate series of investigations by Panorama, we simply wouldn't know about the scale of wrongdoing inside Fifa. He's right also to point to the realities of investigative techniques. One recent Panorama uncovered appalling abuse of patients at the Winterbourne View in Bristol. The programme led to arrests and an immediate stop to the abuse, as well as to an overdue national debate about standards and oversight of all care homes. It was a serious piece of work, manifestly undertaken in the public interest. Yet it necessarily involved secret filming and someone posing as a care worker.
At the BBC, such techniques have to be approved by senior editorial managers and take place within stringent controls. Even with the best of intentions and the most precise of guidelines, investigative journalism is difficult. In Panorama's case, mistakes have been very rare, but when they occur - for example, in a programme about Primark, the inclusion of a sequence of film that could not later be substantiated - they inevitably lead to a close review of our procedures. The ability of the BBC Trust to scrutinise BBC investigations and publish its findings, good or bad, means that our values and tradecraft are held constantly and openly to account.
Whatever the ultimate conclusions of the Leveson inquiry, it is important that the ability of serious investigative journalists to do their work is not blunted or unnecessarily constrained.
Nor I believe should we automatically assume that newspapers should be held to the same level of regulatory supervision and constraint as the broadcasters. Plurality of regulation is itself an important safeguard of media freedom.
The BBC is paid for by the public. Because of that, we would never have paid for the stolen information that helped the Daily Telegraph to uncover the MPs' expenses scandal. The privately owned Telegraph took a different view and was able to publish a series of stories that, taken as a whole, were clearly in the public interest. It is not obvious to me that newspapers that people can choose to buy or ignore - and which, should they break the law, can always be prosecuted after the fact - should be held to the same level of continuous supervision and accountability as broadcasters who reach out into every household in the land.
But there are still searching questions for British journalism to answer. Many newspapers with strong investigative teams and many notable journalists with an outstanding record of holding other institutions and walks of life to account showed a marked reluctance to explore the phone-hacking story until events and the public furore made it inevitable. In some cases, they not only refused to investigate the story themselves but heaped opprobrium on those that did. According to Stephen Glover, writing some months ago in the Independent, for example, "the BBC has conspired with the Guardian to heat up an old story and attack Murdoch".
Even in recent days, there's been an attempt in papers that have nothing to do with News International to suggest that our coverage of the story is far more extensive than other news providers and motivated by spite or glee rather than proper news priorities.
The Daily Mail quoted an Ipsos Mori poll misleadingly this week to suggest that public interest in the story is low. On the contrary, our tracking data suggests it is widespread, with more than 54% of adults claiming to follow the story closely. According to the BBC's critics, we are devoting much more time to the phone-hacking scandal than others. Untrue - the stopwatch reveals that the BBC's Ten O'Clock News has devoted fewer minutes to the story over the past fortnight than News at Ten on ITV1, and our BBC News channel fewer minutes in the key 1700-1800 hour than Sky News. We asked a sample of the public last week how important it was for the media to cover the story: 81% said it was important. And by a wide margin, among the broadcasters they gave the BBC the highest marks for trustworthiness and impartiality in our coverage of it. This is an awesome responsibility that we have to live up to.
Perhaps it's inevitable that newspapers and columnists who are already parti pris on the subject of the BBC find it impossible to judge our coverage except through a distorting mirror of imagined conspiracies and motives. The British public take a more straightforward view and on this, as on every other major story, they simply trust the BBC more than any other news provider to tell them the plain unvarnished truth. I also believe they will give short shrift to those brave souls who are already trying to run the argument that the "real" story revealed by events at Wapping is about the dominance of Britain's public broadcaster and that the right public policy response to phone hacking and criminality at the News of the World is - but of course! - to hobble the BBC.
I believe that what the public want, what this moment demands, is not another round of self-serving hypocrisy or internecine strife from Britain's journalists, but a serious discussion about the difference between good and bad investigative journalism and a complex but necessary debate about where the boundary of acceptable journalistic practice lies and how it should be enforced.
Mark Thompson is director general of the BBC.
This article was first published in the Times.