In the marginal or total revenue? Ie tax = C, or tax = c * income? How would we define fair here? Both of the above options seem somewhat fair: everyone cont

In the marginal or total revenue? Ie tax = C, or tax = c * income? How would we define fair here? Both of the above options seem somewhat fair: everyone contributes the same amount, or everyone contributes the same percentage of income. Or a third standard for fairness could be that the benefit you get from government programs is equal to what you pay in taxes. I don't even know which of these I think is best (let alone a hope of ever changing anything). Perhaps the best way to cash out "fair" in this case would be to start with some assumptions about what taxes are supposed to do; eg solve coordination problems, support disadvantaged people, etc; and see what can be derived.