The Democratic Party's draft platform for the 2020 election cycle sees the world as I did when I was a Model United Nations delegate: A place where foreign policy is a vessel for pious intentions, and informed by the common good.

Back then, I argued that India and Pakistan could sheath the daggers they held at each other's throat — if the leaders in New Delhi and Islamabad simply set aside their blood-soaked history and had a rational, reasonable discussion. So what if Gen. Mohammed Zia-ul-Haq, the Pakistani dictator at the time, was a religious fanatic, menacing his own people as much as the neighborhood? Surely he would recognize the benefits, economic and political, of peace in South Asia?

In my defense, I was 14 at the time.

The authors of the Democratic platform, all grown-ups, have the same faith in Ayatollah Ali Khamenei as my wide-eyed schoolboy had in Gen. Zia. They imagine that the supreme leader of the Islamic Republic will mend his ways if only he can be persuaded that the U.S. is not out to get him.

"Democrats believe the United States should not impose regime change on other countries, and reject that as the goal of U.S. policy toward Iran," they write. Instead, under a President Joe Biden, Washington should "prioritize nuclear diplomacy, de-escalation, and regional dialogue."

That means a return to the 2015 nuclear deal with Iran, known as the Joint Comprehensive Plan of Action. The authors argue that the "Trump Administration's unilateral withdrawal from the JCPOA isolated us from our allies and opened the door for Iran to resume its march toward a nuclear weapons capacity that the JCPOA had stopped. That's why returning to mutual compliance with the agreement is so urgent."

Once that happens, there should be "a comprehensive diplomatic effort to extend constraints on Iran's nuclear program and address Iran's other threatening activities, including its regional aggression, ballistic missile program, and domestic repression."

Under normal political circumstances, all this policy pablum is easily dismissed as the kind of virtue-signaling to be expected from both parties ahead of their presidential conventions. The 180-member platform committee will examine the Democratic draft next week and recommend any amendments before ratification at the convention in Milwaukee next month.

After the conventions, the presidential candidates cherry-pick talking points from their party platforms. Once elected, a president is in no way bound to follow through on the promises therein.

But the Iran-related proposals in the Democratic platform merit alarm, not only because Biden is listed as one of the 15 authors, but because they are consistent with his position on the Islamic Republic. If Tehran complied with the terms of the JCPOA, he wrote earlier this year, "I would rejoin the agreement and use our renewed commitment to diplomacy to work with our allies to strengthen and extend it, while more effectively pushing back against Iran's other destabilizing activities."

As I've pointed out, the former vice president has a history of endorsing woolly and reckless ideas, especially in connection with the Middle East. But few are more dangerous than the notion that Iran can be talked out of its "other destabilizing activities." That catchall term encompasses the slaughter of Sunni Muslims in Syria and Iraq, support for fanatical Shiite militias across the Middle East, the promotion of Lebanese and Palestinian terrorist groups, attacks against civilian shipping in international waters, assistance for the Maduro regime in Venezuela, assassination campaigns against opposition figures in Europe and cyberattacks against the U.S.

Taken together, these activities comprise the bulk of Iran's foreign policy since the formation of the Islamic Republic in 1979. Biden imagines Khamenei can be persuaded to give it all up, in exchange for relief from U.S. economic sanctions and after more diplomacy. That was the expectation of his boss, President Barack Obama, when the JCPOA was signed.

But that was never in the realms of possibility. While the nuclear deal was being negotiated, Khamenei repeatedly said he would brook no discussion about anything else. Nor did he demonstrate any goodwill on this front, much less a change of heart, after the JCPOA was signed. Iran "did not and will not hold talks with [the U.S.] on issues other than nuclear negotiations," he said. "We agreed to hold talks with America only on the nuclear issue and for particular reasons."

Iran stepped up all those "other destabilizing activities" even as the world powers that signed the JCPOA began to dismantle the economic sanctions. Tehran ramped up its support for Syrian dictator Bashar Assad, for Shiite militias in Iraq and for the Houthi rebels in Yemen. Having turned a blind eye to Iran's misbehavior in his eagerness to get a deal done, Obama was unwilling to punish the regime afterward, whether for fear of endangering what he saw as his biggest foreign-policy success or out of consideration for the other signatories.

Trump's withdrawal from the JCPOA was arguably hasty, possibly even unnecessary: A more politic — and defensible — strategy would have been to simply impose tight U.S. sanctions on the regime for those other activities, while giving it no excuse to resume nuclear enrichment and denying the other signatories the high horse from which they now criticize Washington for reneging on a deal.

But to promise a unilateral American return to the JCPOA is to ignore the lessons of recent history. "The nuclear deal was always meant to be the beginning, not the end, of our diplomacy with Iran," say the authors of the Democratic platform. For Khamenei, it was and ever will be the end, not the beginning. As long as he and his ilk remain in power, Iran will remain an intractable menace.

Bobby Ghosh is a Bloomberg Opinion columnist. This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.