There are potential catastrophes so dire, only an approach that blurs the realist and the utopian seems appropriate. Take for example the Treaty on the Prohibition of Nuclear Weapons. Adopted by the United Nations in 2017, it seeks to completely get rid of the most satanic arms ever created.

The treaty’s already been signed by 84 states and ratified by 45. To take effect — that is, to be binding on its signatories — it needs only another handful of ratifications. And this week a group of 56 international bigwigs signed an open letter to nudge that along. They include former presidents and prime, foreign and defense ministers from 20 NATO member states plus Japan and South Korea, as well as one former secretary-general of the U.N. and two of NATO.

One of their stated objectives is to get the current leaders of their countries to sign the treaty. That’s cheeky, since all of the nations in question are presently under the U.S. “nuclear umbrella,” which they’d have to leave or disavow. Unlikely. Several, like Germany, even have American nukes stationed on their own territory.

And then remember that, strictly speaking, none of the signatories so far, nor any of the countries represented by the authors of the letter, even matters. Only nine nations have nukes today: the U.S., Russia, China, the U.K., France, Israel, Pakistan, India and North Korea. And all of them demonstratively boycotted even the talks leading up to the treaty. The chance they’d ever sign is that of a snowball in a fission event.

Does all this make the treaty and the letter a futile indulgence? Quite the contrary. To me, these short texts join a long list of idealist treatises that were never acted upon but nonetheless changed world history. Thomas More’s “Utopia” of 1516 springs to mind, or Immanuel Kant’s “Perpetual Peace” of 1795. Both wanted, among other things, to abolish armies; neither could yet imagine nuclear annihilation, of course.

Neither More, who was being partly satirical, nor Kant, in his realm of pure reason, expected the powers that be to come around to their point of view overnight, or ever. But rather like Martin Luther King when he orated “I have a dream,” they simply confronted us with an ideal state so intuitively compelling, so morally incontrovertible, that the diversions from it in our lived reality began appearing grotesque and unacceptable.

The same goals motivate this treaty. The first is to shake humanity, currently distracted by a pandemic, out of its complacency about the risks of nuclear war. The second is to gradually build a global consensus that eventually makes any military plans built on nukes so shameful that they won’t even be considered. A similar evolution once led to treaties against chemical and biological weapons and land mines.

The first goal, in seeking to correct our flawed risk assessment, is already hard. Since the end of the Cold War, most people have become much less afraid of nuclear war, when instead they should worry more. As I’ve argued before, both game theory and geopolitics suggest that the danger of nuclear conflagration has increased.

The incumbent powers are “modernizing” their arsenals and incorporating nukes into “tactical” scenarios that defy simple deterrence models such as the Cold War’s “mutual assured destruction” (MAD). Upstart powers like Iran want to join the club. Space and cyberspace have been added to land, sea and air as potential battlefields. And then there are imponderables such as artificial intelligence, which makes algorithmic decisions on strikes and counter-strikes in seconds, and all-too-human folly.

The bigger goal is, of course, shaming the nations and leaders that keep their nukes. For instance, stigma could, in time, turn domestic opinion in China and dissuade its leaders from their all-out effort to “catch up” with stockpiles in the U.S. and Russia. It could even sway public attitudes in Russia, India and elsewhere. It could bring the U.S. back to the arms-control negotiating table — the last remaining treaty between it and Russia expires only weeks after the next presidential inauguration.

Two American presidents embodied the imperative to temper nuclear realism with idealism. One was Ronald Reagan, who negotiated with the Soviet Union’s Mikhail Gorbachev to limit their arms race, but who also hewed publicly to this principle: “A nuclear war cannot be won and must never be fought.”

The other was Harry Truman, the only leader who ever ordered nuclear bombs to be dropped in war, but who then helped launch the U.N. to prevent any such thing from happening again. In his wallet he kept what could be interpreted as a poetic version of the Treaty on the Prohibition of Nuclear Weapons. They’re these lines by Alfred Tennyson:

“Till the war-drum throbb’d no longer, and the battle-flags were furl’d, In the Parliament of man, the Federation of the world. There the common sense of most shall hold a fretful realm in awe, And the kindly earth shall slumber, lapt in universal law.”

Andreas Kluth is a columnist for Bloomberg Opinion. He was previously editor in chief of Handelsblatt Global and a writer for the Economist. He’s the author of ‘Hannibal and Me.’