Response:

This myth is belied by the last ten years of experience with Iran.  Iran's sense of grievance runs deep -- it holds the United States responsible for toppling Mossadegh, installing the tyrannical Shah, supporting Iraq in a bloody 8-year war against Iran, shooting down an Iranian airliner, and trying repeatedly to topple the regime, among other things. Clearly, Iran will not accept preconditions for dialogue with the United States, any more than the United States would accept preconditions for talking to Iran. 

But Iran has made multiple peace overtures which the United States has rebuffed.  Right after 9/11, Iran worked with the United States to get rid of the Taliban in Afghanistan, including paying for the Afghan troops serving under U.S. command. Iran helped establish the U.S.-backed government and then contributed more than $750 million to the reconstruction of Afghanistan.  Iran expressed interest in a broader dialogue in 2002 and 2003.  Instead, it was labeled part of an “axis of evil.”  

In 2005, reform-minded President Khatami was replaced by the hardliner, Mahmoud Ahmadinejad.   But the same Supreme Leader who authorized earlier overtures is still in office today and he has vowed that “the day that relations with America prove beneficial for the Iranian nation, I will be the first one to approve of that.” 

This history does not prove that Iran will bargain in good faith with us.  But it does disprove the claim that we know for sure they will not.

Response:

Actually, diplomacy with Iran has not been tried, at least not by the United States.  It is sanctions that have been tried and failed.  For five years until nearly the end of its term, the Bush Administration refused to talk to Iran at all about nuclear issues -- because Iran would not comply with U.S. demands that it first suspend all enrichment. This strategy merely squandered time: while the U.S. sat silent, Iran continued to enrich.

It is true that the Europeans talked to Iran, and they didn’t make much progress. But this is hardly surprising.   Without the United States – the world’s sole superpower and Iran’s chief nemesis – at the table, why should Iran give its best offer to Britain, France and Germany? They would just pocket Iran’s concession, which would become the starting point for later talks with the United States. more

Real diplomacy on this issue has not been tried. What has been tried is threats and sanctions, and everyone agrees they have failed to achieve our objectives.  They may well have set us back by galvanizing Iranian resistance. More of the same is not going to produce different results, and trying for "crippling sanctions" will only make things worse.