The case for higher taxes on the wealthy

[PETRUS]

6. The purpose of taxes.

One of the main functions is to establish a currency. A government issues coins/bills/whatever - say, "dollars" - and demands that taxes be paid in "dollars," which makes the currency valuable and creates a market for it. That is not as widely understood or discussed as the idea of taxes as a way to raise funds. Of course, taxes have historically been used to raise funds (and still are), although the reality is that a government with a sovereign fiat currency does not need to tax in order to spend - such a government can "print" money. Taxes are still necessary for the first reason I mentioned, and also to maintain the value of the currency (printing money for spending and failing to tax some of it back will cause inflation and the currency will lose value).

Other than that, taxes can be used for whatever a government wants (in our case, as a democratic republic that supposedly derives its legitimacy from consent of the governed, whatever "the people" want). The tax code can be used to provide incentives or disincentives for certain behaviors, or to adjust "market" outcomes that are seen as undesirable.

All the reputable, data driven studies I've seen (and there are several, I don't know why your only exposure to a conclusion was a GOP politician) suggest that if the goal is to maximize revenue, the top marginal rates should be between 50% and 75% (depending on the study, and with the brackets defined in relation to median incomes). I have never seen a believable analysis that puts it at 28%. Also, describing high marginal tax rates on top incomes as "punishment" is disingenuous right wing bullshit.