>Randomly assign a representative sample of the population - say, 10,000 taxpayers - a lower tax rate, and see what happens. This assumes the tax rate only aff

>Randomly assign a representative sample of the population - say, 10,000 taxpayers - a lower tax rate, and see what happens. This assumes the tax rate only affects the individual paying tax; but taxes are used at least in part to finance public goods - positive externalities that also affect individuals. If a random group of people personally pay lower taxes but still benefit from the available public services that other taxpayers are still funding, that doesn't tell us anything useful.