The last and most stubborn myth is that of irreversibility. Whenever idealists say that they want to abolish nuclear weapons, so-called realists shake their heads and say, in tones of patient condescension, “You can’t stuff the nuclear genie back in the bottle.”

This is a specious argument. It’s true that no technology is ever disinvented, but technology does fall out of use all the time. (If you don’t believe me, try to get tech support on any electronic device more than three years old.) Devices disappear either because they are displaced by better technology or because they simply weren’t good. The question isn’t whether nuclear weapons can be disinvented, but whether they are useful. And their usefulness is questionable, given that no one has found an occasion to use them in over 67 years.

NOT everyone wants nuclear weapons. What most people don’t realize is that 12 countries have either abandoned nuclear programs, dismantled existing weapons, as South Africa did in the early 1990s, or handed them over, as Kazakhstan did after the 1991 breakup of the Soviet Union. By contrast, only nine have nukes today (the United States, Russia, Britain, France, China, India, Israel, Pakistan and North Korea).

It’s often assumed that Israel would be the last nation to give up nuclear weapons, given its history and a deep sense of responsibility to protect the Jewish people after the horrors of the Holocaust. But Israel has a powerful conventional military, is allied with the strongest country in the world and its leaders have a keen appreciation of military realities. They understand that nukes pose a greater danger to small countries than large ones. Twenty nuclear weapons used on Israel would do far more overlapping damage than 20 used on Iran.

Small nations have always been vulnerable. In a world without nuclear weapons they would preserve themselves as they always have: by forming alliances with the powerful and avoiding antagonizing neighbors.

France, not Israel, would most likely be the last country to give up nuclear weapons, which help preserve its image as a world power. In a nuclear-free world, France would just be another middle-size power with great cuisine. The real value of nuclear bombs is as status symbols, not as practical weapons.

America and other nuclear powers must pursue the gradual abolition of nuclear weapons, but it will not be easy. Many leaders have little interest in giving up power, real or perceived. Any agreement would have to include stringent inspections and extensive safeguards. It would have to include all current nuclear-armed states in a complicated diplomatic process. But bans on other dangerous but clumsy armaments, like chemical and biological weapons, have been negotiated in the past. These bans — like laws — are sometimes broken. But the world is far safer with the bans than it would be without them.