<human>: What is a good argument against a flat tax?
<bot>: A good argument against a flat tax is that it can lead to economic inefficiency, as some people will end up paying more than their fair share of taxes while others pay too little. This could cause the economy to become less productive and reduce overall growth. Additionally, a flat tax may also lead to higher levels of inequality between taxpayers since those with lower incomes would be taxed at higher rates.