I dare say that no classic Austrian economist (Mises, Hayek, Friedman, etc.) would agree with that. In my eyes, they are the only school with a constitent understanding of the negative effects of taxation on wealth creation and freedom, and they would say that any form of taxation that imposes a heavier pro rata burden on the persons that are actually creating wealth (i.e., most effectively employing capital) has a similar disproportionate effect of economic dislocation (again, by taking more capital proportionately out of the hands of the people that are best using it). Progressive taxation is wealth transfer, pure and simple. If you believe in compelled wealth transfer, then yes, I suppose you believe it is equitable - but to me (and those of a libertarian ilk) there is nothing equitable about compulsion. Don't get me wrong, relief of the poor is noble - but only when it is voluntary - again of course, in my opinion.
Indeed, a progressive income tax is not proportionate. It imposes a higher rate of taxation on those with higher incomes. Of course there is a school of thought that taxation should be proportionate. And Hence the use of the adjective "most" when describing economists. More importantly, what are the justifications for a progressive income tax? And, how can a progressive income tax be designed?
Some proponents of a progressive income tax simply advocate wealth transfer. That is, the income tax is considered to be a good measure of wealth, and higher rates are imposed on those with higher incomes so that the revenue flow to the government can be used to provide goods and services to those with less income. Other proponents of a progressive income tax, without necessarily rejecting the first approach, argue that an income tax reflects a payment for the societal costs imposed by those generating income, and that those with higher incomes impose higher societal costs.
I will set to one side the question of whether TAXABLE INCOME, which is used to compute the federal income tax, or ALTERNATIVE MINIMUM TAXABLE INCOME, which is used to compute the supplemental federal alternative minimum tax, are good measures of wealth, or even of wealth increment. I do not think that they are, because they are riddled with all sorts of exclusions and deductions that cause wealthy individuals to report low taxable income and not-so-wealthy individuals to report high taxable income. Toss in credits, most of which are variant manifestations of the same "social policy" engineering reflected in exclusions and deductions, and the computation of federal income tax liability has far less to do with wealth increment than progressive tax adherents claim. Nonetheless, let's consider an income tax that taxes income, period.
Taxation as a mere wealth transfer device seems to fly in the face of libertarian principles. It is the government's business to protect the opportunities that people make for themselves or acquire through effort. It is not the government's business to guarantee outcome. Yet that libertarian perspective must yield, as do other libertarian perspectives, to the reality that "pure" libertarianism cannot exist unless people treat each other appropriately. People, however, don't. Hence, my "right" to drive a car must be tempered by government regulation of traffic signals, speed, and licensing. Most libertarian thinkers, though not all, accept such restraints. The justification is that these restraints are a price that needs to be paid to protect the opportunity to drive (else we'd all be dead very quickly). The justification, though, rests on the notion of protection, or, in other words, safety. Returning to taxation, does not the need to protect the society that provides the opportunities to earn income warrant elimination or amelioration of abject poverty that if left unchecked would cause society to disintegrate? True, it WOULD be nice if voluntary giving and charitable works eliminated poverty, but that hasn't happened. So wealth transfer can be seen more as an investment than a mere transfer. Taxation to support education increases the pool of qualified workers available to those who have the opportunity to employ people in order to earn income. Taxation that shifts wealth can maintain or improve the health of workers so that sick day inefficiencies don't plague the enterprise. There are other examples. True, there are individuals who succumb to the temptation to "live on the dole" which is why efforts, complicated as they end up becoming, are needed to transfer the wealth in ways that benefit society and not just a free-loading individual. Defining and applying the line is a challenge.
Turning to the second approach, it is not difficult to identify the societal costs imposed by those generating income, and to show that when the income is proportionately higher, the societal costs increase disproportionately. This isn't a new idea, and I won't repeat all of the commentary. Consider, for example, the real estate developer who builds a shopping mall or commercial strip. There are societal advantages: jobs are created (though in reality jobs are shifted from other areas as stores close because of the competition from the mall), markets are expanded. But there are costs: traffic becomes congested, increasing pollution and gasoline consumption. The locality's infrastructure, from fire and police protection through emergency medical services to street cleaning, is burdened. Taxes are increased. Some are imposed on merchants, and some on the population of the locality. The developer, having pocketed the profits, is long gone. If the developer doubles profits by building a mall that is twice as large, or by building a second one "down the road," the congestion increases disproportionately. So, too, do the burdens.
The user fees that I have long advocated would solve these problems. However, they would be resisted vehemently by developers. The true cost of most development, and of many other enterprises, causes many to be far less profitable than they appear to be. Consider Microsoft. It is very profitable. But most of its profits reflect the shifting to end users and corporate IS staffs the burden of fixing the mistakes in products rushed to market that aren't ready for prime time. The societal cost in the millions of hours wasted while Service Pack 2 downloads, verifies, unpacks, prepares to install, install, reconfigures, reboots, and then crashes, or while some other fix is installed or bug researched, almost outweighs so-called productivity gains generated by the software. Again, a user fee as I have proposed, such as a $n fee for each time Windows crashes, would obviate the need for an income tax. But it won't happen, will it?
One can also argue that the user fees for some government services, unlike a bridge toll user fee, would be more heavily imposed on those with higher income (assuming income was measured properly as a wealth increment). For example, from an economic perspective military defense is of disproportionately greater value to those with more to lose. Consider that even the provision of human capital to the military is a disproportionate tax on the not-so-wealthy.
So one can see why "most" economists (and others) conclude that a progressive income tax is the most equitable. It is not, however, the most efficient. In its current form, the income tax is horrendously inefficient. And inequitable. Because it is not an income tax but a "tax on the income of those who lack the resources to prevent themselves from being taxed." The earned income tax which I was condemning is the federal income tax taken to its logical extreme: only wages are taxed, because interest, dividends, capital gains, and pensions escape taxation (or are taxed at token levels) because their recipients have the political power and resources to wiggle free of a genuine income tax base. And it was in that posture that I described the earned income tax as violating, in effect, the principles of everyone, whether advocating progressive taxation or proportionate taxation. There simply is no justification for taxing earned income and not other forms of income. None. Period.
I don't like the federal income tax as it now exists. Or has existed. I don't like state and local income taxes. Or earned income taxes. I prefer user fees. I understand that user fees are "regressive" because they claim a higher share of a lower-income person's income than they do of a higher-income person's income. But so, too, are the fees for food, clothing, and other necessities. User fees, after all, are simply the prices charged by a supplier who happens to be a government. (Yes, I know that privitization of many government functions makes sense, and would shift charges from a "user fee" to a mere "private sector price" but I don't want to stray into that discussion at this time.)
There is, however, one sort of income tax that I could support. It is on its face not progressive but it is when it is carefully analyzed. To the advocates of wealth transfer I argue: If income is being used to measure wealth increment as a basis for taxation, then let's accept what it means to be "wealthy." A person is "wealthy" if they have something left after paying for food, clothing, medical care, shelter, and the like. So what's left over (assuming income is measured properly) is what should be taxed. To the advocates of "income tax as paying for societal costs" I argue: "Those who pay for what they eat or wear, etc., are paying societal costs as built into the price. So let's deal with what's left over."
With a goal of minimizing the current paperwork and compliance nightmare that stalks the income tax, the notion of requring each person to keep track of what they spend would be contrary to simplification goals. A poverty level income is calculated annually by the government. Take a percentage of it, say 125%. Each person computes income, subtracts this amount, and pays a tax of, say, 30% of the excess.
Is it progressive? Of course. Let's say the 125% level amount is $20,000. A person with $18,000 of income has no tax. A person with $25,000 of income has a tax of $1,500 (30 percent of $5,000). That's 6% of income. A person with $40,000 of income has a tax of $6,000 (30 percent of $20,000). That's 15% of income. A person with $500,000 of income has a tax of $144,000 (30% of $480,000). That's 28.8% of income. Looks awfully progressive to me.
As for revenue, with exclusions eliminated and deductions limited to the cost of generating income, a lot more goes into the initial computational base. I used numbers that were easy for computation. It would not be too difficult to determine a number that is revenue neutral.
There are other advantages to such a system. I wrote about those advantages in Section VI of TAX AND MARRIAGE: UNHITCHING THE HORSE AND THE CARRIAGE, 67 Tax Notes 539 (1995) and I'll let you go read it. That was almost ten years ago. Of course nothing has happened to move us closer to a sensible tax system.