Maybe a flat tax isn't such a good idea after all...

[Alpha]

...what is to stop the devious liberals from turning that into a 10-10-10 plan or a 11-11-11 plan? You know the liberals are going to find some sort of way to force their big government agenda on the American people, so they're going to try to use our own tax system against us and subsequently, against the American people.

Because there are no social democrats in America? Because anyone who supports any degree of marginal taxation is not an American citizen? Honestly, you talk as though you live in a dictatorship, not a democracy. If American people vote for candidates who represent certain policies, then it is sensible that those policies are then enacted to reflect their democratic mandate. If you judge policy based on how little influence "liberals" can/can't have over it, all you're doing is devising a way for democracy to stop functioning. I find that repugnant.

Also, a flat level of taxation is a terrible idea, that's why it doesn't exist anywhere (to the best of my knowledge). "European socialists" don't support 90% taxation. Sales tax is the most regressive form of taxation, and I'd much prefer it to be scrapped in favour of higher income taxes.

Wealth and income are assumed (sensibly) by economists to have a declining marginal utility. That is, $100 to a poor person is worth more than $100 to a very rich person. While a flat tax rate in dollar terms still takes more from rich people than poor people, if you take proportionally more from richer people to compensate for a lower proportion among poorer people, total utility will still be higher; marginal taxation is more efficient than a flat tax.

Moreover, it's fundamentally more equitable, both horizontally and vertically. Richer people can afford to surrender more of their income without sacrificing their essential standard of living than can poor people: that is, people in different circumstances should be treated differently.

A sales tax is horrible as a tax, and positively harmful as a primary revenue-gathering measure. It places a much greater burden on poor people than on rich people -- that is, as a proportion of income, poor people will pay MORE in tax than will rich people. I could support it if it exempted 'necessary' expenditure, such as rent and food, and would doubly support it if it was exempted on healthy food but not unhealthy food. However, not only is that difficult to implement (is the lettuce in a McDonald's burger exempt?), I still wouldn't be happy about it.