The degree to which any given type of taxation is fair depends largely on how a person wants to define “fairness” with regard to taxation. Social scientists typically identify two ways of defining fairness in taxation.
The first of these is the “benefits received” definition of fairness. From this point of view, it is the people who benefit most from government spending who bear most of the burden of taxation. This makes sense because we would typically think that the people who enjoy a thing are the ones who should pay for it. By most definitions, it is not the people with higher incomes who benefit the most from government spending. Therefore, they should not be the ones to pay the most and progressive taxation is unfair.
The second way of measuring fairness is the “ability to pay” definition. By this way of thinking, it is fair to have the people who are most able to pay taxes pay the most taxes. This makes sense because it is clearly logical that the people with the most money can most afford to pay taxes. Clearly, the people with higher incomes are the ones who pay more in a progressive tax system. Therefore, this is a fair system when viewed from this perspective.
The fairness of progressive taxes, then, depends on the definition of “fairness” that is being used.