Is society better off if you take 100 mil in income from Larry Ellison and Sundar pichai and build a few hundred units of low income housing? Even if it pisses off ellison and Google pays pichai less the next year?
A utilitarian could (and has) claimed that this marginal dollar occurs at the point where you have the bare minimum to survive: https://www.lesswrong.com/posts/Y4Adk743X2ZoMBSBi/does-utili...
>"For example, utilitarianism apparently endorses killing a single innocent person and harvesting their organs if it will save five other people. It also appears to imply that donating all your money to charity beyond what you need to survive isn’t just admirable but morally obligatory. "
So I don't think a strictly utilitarian argument is sufficient.
There's a few problems with this line of reasoning:
1. Its not clear to me that this argument is being made by a utilitarian, as you claim
2. You at least appear to show a misunderstanding of what "the marginal dollar" is. Every dollar is the marginal dollar. Its just that the relative value of dollar 1 (which you need to survive) is greater than the relative value of dollar 1 Billion, which you use to, uhhh, buy an island. I think what you're saying is that there is a point where the marginal value of your dollars is low enough that you are ethically obligated to donate them is at or around subsistence level, and that might be true, but it leads to the third problem:
3. Even for a strict utilitarian, if you take into account externalities, the right thing to do might not be to take all the money away from people. If you're optimizing for something like reducing death, reducing everyone in the US to subsistence level probably isn't the best solution: you'll likely do something unwarranted like cause a revolt. This has two major net negatives: a bunch of people die in the revolt, and you end up losing a lot of your money, either because you spend it to put down the revolt or because you don't and you lose and people take it back.
4. While improving the life of those in absolute poverty is a laudable goal, it's not clear that it makes sense for a government to do that, except when it ends up being beneficial to the government or its people. In other words, a government's moral imperative probably doesn't extend (far) beyond its borders.
> So I don't think a strictly utilitarian argument is sufficient.
People often forget about externalities.
On the other hand, if you think of the supply of billionaires as a revenue source, and then you think of there being decreasing demand for being a billionaire as taxes go up, but increased revenue per billionaire as taxes go up, you can draw up supply and demand curves and optimize to maximize revenue from billionaires (or people in general really, its just that the marginal rates can likely be higher on billionaires and they're the talking point of the day). If there are 100 billionaires, and you tax 2% more, and 1 billionaire moves away, you're still up on revenue. I often hear people arguing that we should operate our government more like a business.
This is actually one of the standard strategies for taxation: we should setup a tax system that optimizes for the maximum total tax receipts. When you tax too much, incentives go down and you actually lower your total tax receipts. In principle, there is an optimal taxation amount.
The problem with this approach is that we don't have good enough data. No one really knows how many fewer billionaires there would be if we increased their taxes, and biased interests each have plenty of conjured data to make their argument.
There are other tax strategies as well: trickle down economics (a favorite of the right, also based on suspect data); and guaranteeing living wage (a favorite of the left). One advantage of the latter is that the argument is not based on numbers or data, but on morality.
But that's not the only thing that happens though.
A prospective billionaire that is not yet a billionaire might think "there's little point in putting in all this work on this new project, because the government will take more of my money".
Another thing that can happen is that a foreign company decides to invest somewhere else because of that tax. They might look at the tax and expect it to discourage investment internally and look for potentially better prospects.
Elon and Bezos send people to space with the wealth they fairly gained. The government prints trillions of dollars every year to fund their deficits and wars. If the government needs another billion dollars, it’s quite easy for them to create it.
Why seize money from the rare person who is talented enough to make so much of it?
Would you want to live in such a world? Or do you think maybe the rest of us deserve to have some of that water, even if we're not as clever and we didn't "fairly" earn it?
Dialing back to the real world, all these billionaires and other elites are having very real outsize impacts on the lives of the less wealthy -- from whether/where/how they work, to how they and their children get educated, to what information we have access to, to who goes to jail and who goes free, who goes to war and against whom, and who lives or dies.
Incredible wealth gives people incredible power, and the concentration of this incredible power in the hands of a small minority is distorting the world in ways those not in this minority are having trouble swallowing, no matter whether this concentration of wealth and power was "fairly" arrived at or not.
But, yes, giving up some of what they own is one way of dealing with it... though one could argue that by the time they have control of all that water or wealth, it's too late, because by then they have so much power that they, not you, get to call the shots.
Another way is to change the system so that they don't gain so much control in the first place, and so that water (or wealth) is distributed more equitably among all seven billion of us instead of just a tiny few.
The government spends trillions on wars exactly because of the power concentration you are defending. It's not the common man that decides to go to war, it's the network of wealthy people who benefit from it.