The role of investigative journalists remains crucial in holding power to account, even when that power is ‘incompetent’, according to veteran reporter Seymour Hersh.

“The whole purpose of what I think we should be doing is counter-narrative. They have their narrative, and we have to show there is another narrative,” said Hersh, in a keynote session at The Logan Symposium conference in London.

“Even if you can’t publish, the act of asking, the act of doing, the act of putting it down. It’s all about an informed society, and you’re not going to get informed by the leadership. That’s our function.”

Hersh, whose award-winning work include reporting on the My Lai massacre in south Vietnam and more recently the Abu Ghraib prison in Iraq, gave a sparky speech blending advice for young journalists and hackers with brickbats for the US National Security Agency (NSA).

“My view is very simple: the world since I have been old enough to read has basically been run by idiots, nincompoops, thieves... and unfortunately the solution is the idiots who run most of the mainstream media,” he said.

Hersh, who was interviewed on-stage by author and broadcaster Laura Flanders, said journalists should not run scared of bullying by governments and intelligence agencies.

“Let me say this to you real simple: when you have something like these stolen documents, and you decide you’re only going to publish part of it. We’re not breaking the law. We’re not the guys that are violating the rights around the world,” he said, before referring to the Guardian’s decision to destroy hard drives of files leaked by NSA whistleblower Edward Snowden.

“So why be afraid? Why not write everything? Do it. As the Guardian guy did, why let some thugs come into your office and destroy some documents that you know don’t exist elsewhere?… We shouldn’t hesitate. The guys who should worry are the guys who are violating the laws.”

Hersh had a barb for his former employer, the New York Times, suggesting that young investigative journalists do not need mainstream media accreditation to do valuable work.

“You don’t have to be in the New York Times or something like that. The New York Times is narrative. You want to be counter-narrative,” he said. “Mostly I’m embarrassed for the paper these days, having worked there. And that doesn’t mean it isn’t the best there is.”

He reserved his biggest criticism for the NSA, although he portrayed the agency as incompetent rather than malevolent. “The single most overrated agency in the United States is the NSA,” said Hersh.

“It is so fucked up. They can’t get anything right! It’s just the most useless unproductive agency. It doesn’t get much. Yes, any given day if they decide to go after you, they can do a helluva job. But they always could… But it’s also a question of how do they retrieve it. I’m not worried about them.”

Hersh suggested that the danger posed by the NSA is less about what it has been doing so far, and more about what it could do in the future under a more competent leadership.

“Snowden shook up the community, big-time. How many Snowdens are there? They don’t know. They worry about it, because they’re very, very sloppy… They don’t even know what hey’ve done wrong. They can’t find out,” he said.

“It’s a completely dysfunctional place. And I think we can’t get to it because of secrecy… It’s an agency that needs to be cleaned up. It’s a menace to itself because they’re incompetent, but if somebody competent got in there…”

Hersh called for more collaboration between journalists and encryption experts, warning the latter group that the former often need more help getting to grips with online security technology than they might expect.

“You guys who know an awful lot about computers, you have to do more for the dummies. You aren’t doing enough for the dummies… I know you all think encryption is easy, but it’s not for a lot of people,” he said.

However, Hersh added that for him, being a technological “dummy” is in part a strategy for protecting sources.

“I don’t put anything into a computer, and I like it that way. You pick up my iPhone, and I’ve got my wife and kids, but you won’t find anyone who even comes close to being a source. That’s how I protect people, I keep them off the internet.”

Hersh finished by returning to the theme of the role investigative journalism plays in a healthy society.

“We are here to keep them in check, to keep the powers that be in check. That’s the only thing between them, and chaos – fascism if you like. Because they lie. They are frigging liars, because it’s so easy to lie,” he said.

“We have a role to play. We can at least keep them afraid of us.”

• Liveblog: The Logan Symposium – secrecy, surveillance and censor

http://www.theguardian.com/technology/2014/dec/05/seymour-hersh-nsa-surveillance-useless