My best (stupid) guess is weapons. US gov has a ton of weapons. Already sells tons of weapons. Now the prices will always remain stable. Other countries would love to know that 30 million usd would always be able to buy an f15. Other countries declaring war will increase the value of the USD, as buying weapons from us government will decrease amount of money in circulation.
I would peg it to the number of weapons (manufactured prior to the change) that are destroyed by that country, plus the number of millionaires and billionaires taxed at more than 50%, less the number of weapons manufactured or purchased by that country in a year and the number of citizens living at or below the poverty line.
Now, if the US doesn’t want the value of the dollar to go down, it has to destroy three nuclear warheads and 10,000 assault rifles every year, and house 10,000 people and hike up taxes on Musk and Bezos. China could make the yen a very attractive investment by pledging to destroy their entire nuclear arsenal, driving the value of the yen way up. Russia would go broke even more quickly than they already are as the value of the ruble plummeted.
“What happens when the whole world is disarmed and everyone is housed?” Uh, I dunno, man. Mission accomplished? Like, we should be so lucky to be faced with such problems. And really, in a world without weapons or billionaires, in a world where no one is unhoused, do we even need money anymore?
If we find it still serves our interests to maintain a financial system, tie the value of currency to the elimination of a different societal ill (disinformation, maybe?). Or tie it to scientific discoveries made, or works of art created within each country’s borders.
That’s not how backing works…
You can’t back something with a lack of something, that’s just a scheme to reward actions if the actions are performed by others, or nonsensical if they’re performed by you; you know the government’s just going to produce more cheaper and low quality weapons especially for destroying if that’s how the value of the dollar works.
You also need to have two way exchange of the same material - if you give the government 1 dollar they’ll destroy weapons for you, but in that situation you should be able to exchange that one dollar for your thing back, but what do you get? Do they reproduce the weapons? Do you have to destroy your own weapons? What if you don’t have any?
I know that. But if I’m given the chance to change the way it works, why limit myself? Choosing a random commodity is boring and doesn’t solve the underlying problem.
Hence the destruction of weapons created before the edict, minus all weapons created or purchased.
This is just shifting the problem forward to the endgame of a disarmed, de-billionaire’d world. In that world, currency would represent “some positive benefit to humanity,” so maybe you get a portion of a park named after you, or a tree planted in your name.
I know that there are many, many problems with this idea. I am under no delusions that this would work. But the idea is interesting, and thinking about ways that we could incentivize the governments of the world to act in the interest of the world’s people is probably a useful exercise.