Last week’s tentative agreement on the Iranian nuclear programme sparked a great deal of debate in the US, with the Obama administration and its critics in congress haggling over a “good deal” or a “bad deal”. Others have highlighted the differences between the American fact-sheet, released by the White House on the key parameters of the deal, and an Iranian version.

But Iran has also opened up, allowing public discussions to an unprecedented degree between those who believe the Iranian negotiating team are on the right track and others who say they are not telling the full truth. Iran’s state TV, which raised eyebrows as it broadcast Barack Obama’s speech live in the immediate aftermath of the Lausanne preliminary agreement, has grilled the country’s foreign minister over the issues that have been mentioned by the US but downplayed at home. Other Iranians have scrutinised the US fact-sheet in public almost line by line.

One person stands out among those in Iran who want an end to the long-standing dispute over the country’s nuclear activities. Sadegh Zibakalam, a professor of political science at Tehran University, has become a familiar face in Iran for his passionate and daring debates with hardliners on national television and radio or at roundtables hosted by various institutes, in which he publicly challenges the state line on many sensitive topics. In the absence of serious political dissidents, who are either silent after the 2009 crackdown or still in jail, Zibakalam singlehandedly fills the space of an entire opposition. He is an outspoken critic still being tolerated by the ruling establishment. He made headlines last year when he said he recognises Israel because the UN recognises it as a state.

And earlier this week, Zibakalam went head-to-head with a conservative member of the parliament, Hamid Rasaei, his usual sparring partner in such discussions, talking about the pros and cons of the outcome of the latest negotiations in Switzerland. After so many similar appearances, the two have become familiar with each other’s talking points and often exchange comments referring to their previous sessions. Nevertheless, they are popular and touch on issues considered taboo for a long time. Zibakalam’s Facebook page has attracted more than 350k likes. He clearly lives up to his name, which means “eloquent speaker” in Persian.

Monday’s discussion between the two, held at the Young Journalist Club in Tehran, was remarkable as they locked horns over the recent negotiations. Zibakalam made clear that in his view the political understanding reached in Lausanne was a defining turning point in the history of the Islamic republic. “Some events are considered as turning points in a country’s political life, for example Iran before the revolution and Iran after the revolution,” he said. “I believe Lausanne will become one of these turning points for Iran.” Iranians have had good reasons for having deep suspicion of the US, as a recent Intercept article study, but Zibakalam said for the first time since the 1979 Islamic revolution, the Iranian establishment, or at least some of its factions, is studying whether Iran and the US can overcome that mistrust.

Rasaei, in his part, rejected President Hassan Rouhani’s comments that the Lausanne agreement was a win-win outcome. “Even illiterates, hawkers, or even taxi drivers in Iran know that a decision is up to him [Obama]... Not only we did not win, but we were defeated.” Zibakalam fired back by saying that Rasaei’s problem with the talks does not stem from the details of an agreement but from his ideology, accusing him and his sympathisers of making a career out of anti-Americanism and anti-imperialism. “You give that away from these people and they have nothing to say,” Zibakalam said.

In his defence of the efforts to end the nuclear dispute, Zibakalam went so far as to questioning the establishment over its obsession with the nuclear programme. “I asked [senior negotiator] Aragchi what would you have to say to your grandchild if he comes to you in 30 years time and asks you what did you gain in return for spending so much on the nuclear programme?” Zibakalam argued that the programme, especially the enrichment cycle, was not cost-effective for Iran. “How many people work for our atomic agency, how much budget does it have? [Compare that] to the money designated for our health, this is the real issue.”

Rasaei attacked Zibakalam for questioning the nuclear programme, saying it symbolises Iran’s struggle for independence today. “Mr. Zibakalam, why did you go to jail [under the late Shah’s rule]?” Rasai asked, trying to remind the professor of his revolutionary past. Zibakalam did not hesitate to respond: “I went to jail for democracy, so that we wouldn’t have political prisoners in the future, so that we wouldn’t have [opposition leaders] placed under house arrest.” Zibakalam, who has been critical of the situation of human rights in Iran, was referring to the house arrest of opposition leaders, Mir Hossein Mousavi and Mehdi Karroubi.

A high point in their debate was when Zibakalam said the world is suspicious of Iran over its anti-Israel bellicose. “Brazil, Argentina and India all have nuclear programme but Iran is the only country which has announced it wants to destroy Israel... who has given us the duty to destroy Israel?” Zibakalam said. “Israel has never said it wants to destroy us ... Even Palestinians recognise Israel. We are more catholic than the pope.”