The progressive income tax is a tax structure where the tax rate increases as an individual taxpayer's income increases: the higher the taxpayer's income, the higher the taxpayer's respective tax rate.
The progressive tax does of cause not exist merely for economic reasons. The progressive income tax can be used as a tool to distribute income or wealth or to be punitive, but that would be a deliberate choice and is not an essential component of the progressive tax . However it is the only way in an income tax regime to accomplish that.
In fact the ability to pay theory, arguing that higher-income individuals should have a higher tax rate and burden due to their abilty to fund the government is probably the most established justification and