Does this denounce the form of income tax levied by the civil authorities? I’ve heard some that argue in the affirmative, but I’m skeptical.
I suppose you are referring to the phrase “burdens are imposed unequally on the community”. Aquinas chose his words well. So consider what a burden it is for person with a million dollar income to pay a tax of $2000. Then consider what a burden it is for one who is in poverty to pay $2000. It is obviously a much larger burden on the one in poverty to pay the same dollar amount tax. So a fixed dollar amount tax would be an example of imposing burdens unequally. Now it is rare to find a tax that is levied in this manner (a fixed dollar amount), except for small things, like tolls on roads. Most large taxes are either in the form of a flat rate (a percentage of the person’s income) or a graduated rate (a graduated percentage of one’s income). Both of these methods are an attempt to equalize the burden on the community. One could argue that a graduated tax goes too far in burdening the wealthy. But such an argument would have to be made on its own merits - not on a mindless application of the phrase used by Aquinas. For if Aquinas denounces the graduated income tax, then he also denounces the flat rate tax, because the flat rate tax is also unequal in a sense. A 5% flat rate tax would have the millionaire paying $50,000 while the person who only made $20,000 would be paying $1,000. There is no reason to consider the percentage as any more relevant to the amount of burden than the actual dollar amount. So to those who would argue as you suggested, I would ask how they can justify a flat rate tax over a fixed dollar amount tax, in light of this quote by Aquinas.
A fair tax is a misnomer. The poor, working poor, and even the majority of the middle class spend either all or the vast majority of their incomes. Therefore they’re taxed on essentially all of their income, no different than an income tax, albeit likely at a higher rate. Where as the wealthy typically spend just a portion of their incomes on life expenses, which leaves them just paying taxes on a small portion of their income. Which would likely be taxed at an even lower rate than what they were paying. A large portion of their income would go tax free, be invested, and allow an even more rapid accumulation of wealth at the expense of the poor and middle class. This is the very definition of a regressive tax, one that places the burden on the poor and working classes.