This is a contribution to the Moral Economics sequence.

At a given price level, there is a an optimal bundle of goods and services that maximizes a consumer's preference satisfaction. This means that given that you are consuming such an optimal bundle, you cannot increase your preference satisfaction by buying more of one good or service and less of another - e.g. more gym classes and less video games.

Suppose, however, that an external actor subsidizes gym classes (e.g., your parents, the government), but not video games. Then you might increase your preference satisfaction by buying more gym classes and less video games. Indeed, that is the point of such subsidies.

Similarly, the government's optimal bundle of goods and services - which is a function of the voters' preferences - may change if certain goods and services are subsidized. For instance, if someone is willing to top up each extra dollar the government spends on foreign aid with ten extra cents, it might rationally decide to spend more on foreign aid, and less on other policy areas. (Exactly how large this top-up would need to be would depend on the marginal utility that the government gets from more foreign aid spending, and the marginal disutility it gets from less spending on other policy areas.)

No doubt there are people willing to make such top-ups, which gives room for moral trade  - a notion developed by Toby Ord - between them and the government. Like all forms of trade, such trade would increase both parties' preference satisfaction.

In principle, anyone could take part in such a moral traed (e.g. another government). Here I am going to focus on a special kind of moral trade with the government, however, namely ear-marking your tax money for a special policy area (e.g. foreign aid) for a certain price. People could be allowed to ear-mark all or parts of their taxes for a particular policy area of their choice, if they paid for it via a higher tax-rate.

My guess is that a fair number of voters would accept this offer even on terms which are quite favourable for the government. If so, allowing people to ear-mark their taxes for a price should be very advantageous for the government. The fact that it got more tax money would outweigh the fact that some of the tax money was ear-marked.

Also, note that these ear-marked taxes will to some extent cancel each other out. If four tax-payers, who pay an equal amount of tax, ear-mark their taxes to four mutually exclusive and equally large policy areas, the government will get more tax money in total without the distribition of government spending having been changed. In practice, some areas are going to be more popular to fund, however, which means that this will perhaps not be the normal state of affairs.

Another advantage is that people might feel more motivated to pay their taxes if they knew that their taxes were going to something they felt strongly about. That could mean less tax evasion. It could also mean that people started to think of their ear-marked taxes as something more akin to charity, and less like taxes in the classic sense. It would feel like less of a burden.

One possible worry that deserves comment, though, is connected to the notion of counterfactual trust (which Ord mentions) and replacability arguments (which, e.g. 80,000 hours have used a lot). Suppose that lots of people start ear-marking part of their taxes for foreign aid. Then the government might be disposed to reduce the part of the general pot of money - coming from non-ear-marked taxes - that goes to foreign aid. In the end, the ear-marking will have led to very little extra spending.

This constitutes a breach of counterfactual trust - the government doesn't distribute the general pot of money in the way it would have done if there hadn't been any opportunity for moral trade, because it thinks that in this way, it can maximize its moral preference satisfaction. I don't see a moral problem with that (which can be the case with other forms of breaches of counterfactual trust), but there is a potential pragmatic problem. If tax-payers see this happen over and over again, they might be dissuaded from ear-marking taxes for their favourite cause.

One way to get around this problem is to explicitly refrain from such redistribution of the general pot, at least the first few years. Inevitably, I think that there will be some such redistribution in the end, though.

Potentially, it won't make that much of a difference, though. We know that people have problems getting these replacability arguments. Lots of people don't just want more money to foreign aid - they want their money to go to foreign aid. If that's right, issues of replacability and worries of breaches of counterfactual trust are less important.

Another worry is that this would introduce a certain element of unpredictability in the government budget - particularly if these sorts of ear-marked taxes became common. Temporary shortfalls in the general budget could be covered by increased government borrowing, but unexpected extra funds would normally have to be saved until new capacity to use them has been added. That would probably be a minor problem, though, as would the extra admin work this would incur.

One objection is that this would give rich people, who pay large amounts of taxes, an undue influence over government spending. It is indeed true that this system would give them a better chance of satisfying their moral preferences. However, the government's moral preferences would also be better satisfied under this system (since it would only take part in such transactions that increases its moral preference satisfaction). Thus it is not true that the gains that rich people make happen at others' expense. Everyone wins from trade - this is not an exception.

As some readers might have noticed, there is a similarity between this system and charity tax-deductions. The main difference is that under a system of ear-marked taxes, the controls of where the spending went to would be much more rigorous.Today, you can get tax-deductions for donations to all sorts of highly ineffective charities. Under this system, you could only ear-mark your taxes for something that the government has already deemed spending-worthy.

Has this idea been put forward before? Has it even been tried in practice, perhaps? If not, one could test it by letting people ear-mark small parts of their taxes to a small number of areas - say foreign aid, health care, education, etc. Perhaps it would be most interesting to test it in a country where you can't make charity deductions, since there's bound to be some competition between tax-deductible donations to charity and ear-marked taxes.

I'm not sure whether this would be a good idea, though, and am open to counter-arguments.