The suggestion is to establish a Regressive not progressive tax rate. Making more money is incitement enough.
The problem with a progressive income tax that increases is this. When a person makes more revenue they are not paying the same rate on old revenue. They are paying the new higher rate on revenue they were previously paying a lower rate. Let's say the increments are 10, 30, 70. Once a person crosses from 10 to 30 they now pay 30% on revenue they were only paying 10% on. So if you are only one dollar into the higher tax bracket you end upmoaying that rate on every other dollar before it which ends up being a huge tax increase.
That's not how it works. You cannot go from one tax table to another by $1.00 and loose money. The new rate does not apply to all your earnings; instead, you are taxed at a certain rate up to a dollar amount and only those dollars in excess of that are taxed at a higher rate. Here is a chart from Forbe's which simplifies things:
IRS Announces 2014 Tax Brackets Standard Deduction Amounts And More - Forbes
From the chart, you can see that if your taxable income is no more than $9,075 the tax rate is 10%. This means that the most you could pay in taxes is $907.5
If your taxable income is more than $9,075 but no more than $36.900 you pay $907.50 (10% of the first $9,075) plus 15 percent of income in excess of $9,075.
If your taxable is more than $36,900 but no more than $89,350. Your taxes are $5081.25 plus 25% of all income over $36,900. That $5081.25 is calculated as follows: $907.50 (10% of the first $9,076) plus $4,173.75 (15% of the next $27,825, which is $36,900 minus $9,075).
As you go from one tax rate to another, only that income which is in excess of that which qualifies for the lower rate is taxed at the higher rate. I hope that explains things. I worked for the IRS some time ago and I know how the tax code works.