Petrel Resources' Managing Director David Horgan has set foot in war-torn Iraq, but he seems a bit awed by middle-aged television presenter Duncan Stewart. In fact, the snowy haired environmental guru, with some help from communications minister Eamon Ryan, is trouncing the enviro-sceptical Horgan and his co-conspirator, Paul Sommerville of Delta Index, in a live Leviathan debate on 'the economy versus the environment'.

Stewart is such a whirlwind of convincing facts, figures and utopian projections, that when an audience member addresses a question to 'the minister', Stewart fields that as well.

"'Minister' Duncan Stewart now, is it?" asks the host, David McWilliams, with his eyebrow raised high above his casual leather jacket and stylish Converse runners.

In the end, many of the more thoughtful challenges to the green agenda come from McWilliams himself, or the seated and politically-astute audience (one audience member accuses Ryan and Stewart of trying to keep Ireland in protectionist poverty; another lambasts the minister for the government's handling of a Kerry-based biofuel business).

And that's as it should be. Leviathan is built on audience-participation. A live-panel debate held regularly at the Button Factory and sponsored by Delta Index, it's run by political consultant Naoise Nunn and former radio producer Amanda Brown, and hosted by the economist, broadcaster and writer David McWilliams.

Each instalment sees panels of politicians, journalists, business people, activists and rabble-rousers arguing over the big issues on front of an opinionated, well-informed and alcoholically-lubricated audience.

Former panellists have included Michael O'Leary, Eamon Gilmore, Irvine Welsh, Naomi Klein and controversial British Islamist Anjem Choudary ("you should have seen the security for that one," the sound-engineer tells me), and there are also short films from Derek O'Connor and Ian Whelan, and comedic contributions from regular satirist Paddy Cullivan (and on this occassion comedian Jarleth Regan).

Now, as a contribution to public oratory, Leviathan isn't quite like the Greek senate, the salons of Mme Geoffrin, or one of Daniel O'Connell's public meetings.

It's more like a big sprawling (albeit entertaining) pub argument, but that's exactly what founder Naoise Nunn was aiming for. "I started this because the pubs were too loud to talk in," he says.

"My idea of a perfect night out is a good healthy argument with some humour in it. I wanted to provide an alternative forum for political engagement – a public conversation. I couldn't, and still can't, see a great deal of difference between what's offered in the different media organs. I wanted to shake things up a bit and have somewhere where minority views could be aired and discussed."

Leviathan is certainly less reverent than its television and radio counterparts, with boisterous audience members emitting the odd cat-call, and McWilliams unceremoniously slapping down impenetrable waffling ("I'm a bit stupid, you're going to have to explain that").

"There's an unfortunate sterility that comes over people in a television studio," says McWilliams. "You have old presenters and old producers dominating an agenda which I believe has completely changed. The official television channels pay complete lip-service to the political parties.

"Here you can go where the debate takes you and don't have a voice in your ear saying: 'you have to give two minutes to the Fianna Fáil guy now'. The politicians are Carr-communicationed and Terry Proned to within an inch of their lives. But there are some idealists in politics too, and at something like Leviathan they can let their guard down," he laughs. "It's amazing what five pints can do."

So would they ever consider televising it as a rowdier counterpoint to Questions and Answers? "It would have to be called 'Questions and Chancers'!" says McWilliams. "I think RTE are bloodletting and culling so busily that they aren't concerned with the likes of us. That said, if they're serious about the public broadcasting remit then they may have to entertain the notion of opening up debate a little bit," he pauses to laugh. "I'm the only person who's been fired by TV3, Newstalk and RTE so I'm qualified to talk about this."

Nunn thinks that Leviathan fits into a changing political landscape of blogs, online communities and a new era of heightened political sophistication amongst young people.

"I think we're entering really interesting times," he says. "The old political order is changing and party political loyalty, clientele-ism, parish-pump politics, and dynastic politics are fading. The political system that has done us for the last 70 years isn't capable of coping quickly enough or appropriately enough with the current problems.

"I think there's a new political dispensation developing among the public and I think things like Leviathan help."

Indeed, Nunn is uniquely qualified to speak about the transformative power of political debate, having gone through a very public change of mind himself in recent months. Formerly a director with anti-Lisbon campaigners Libertas, Nunn has now decided he supports a 'yes' vote.

"As John Maynard Keynes said, 'when things change, I change my mind, what do you do, sir?'" he says.

"Look, your views are only as good as the challenges they overcome, and the current challenges overcame my view that the Lisbon Treaty should be rejected. I think that's a good and healthy thing.

"And I think that's what Leviathan offers – the other view, the minority report, if you like. Whatever the opinions are, we'll have a look at where the cracks are and challenge them. I think the value of holding a political or cultural view is undermined if it's never challenged."

Leviathan is on this Wednesday in the Button Factory and asks: 'does Ireland now need radical political reform?'

The panellists include Minister Noel Dempsey, Killian Forde and Ciaran Cuffe. You can also catch Leviathan at MindField, the spoken word arena at the Electric Picnic, in September.

Some memorable debates

December 2003 The first Leviathan was hosted by Des Bishop and featured the late, great Ronnie Drew singing a collection of protest and workingman's songs.

March 2005 'What have the British ever done for us?' coincided with the British Council releasing a series of essays on Ireland's relationship with Britain and satirical balladeer Ding Dong Denny O'Reilly led the audience in chanting: "Spit at the Brits" and "Ooh, Ah, up the 'RA"!

March 2006 Are the West and Islam on course for a clash of civilisations? This featured UK Islamist Anjem Choudary. Gardaí were posted in and around the venue and Choudary spent half an hour on the phone to his Imam receiving instruction on whether he could go on stage in a venue serving alcohol.

June 2006 Debate on European attitudes to the US was filmed for the American TV network for a programme called The Anti-American. Senator David Norris and Declan Ganley were on the bill.