Alright, TurtleDude. This is a probably thankless exercise, but at least I'll have it to refer back to if you ever accuse me of refusing to engage with you.
First, the basic premise of the protection theory is flawed. Government protections extend to much more than property. The Founding Fathers made clear their vision for America in the Declaration of Independence when they spoke of the “unalienable rights” of all Americans to “life, liberty and the pursuit of happiness.” There is no basis for believing that a low-income person’s life is worth more or less to an individual (as contrasted with an insurance actuary, an economist, or a jury assessing damages in a wrongful death case) than the life of a high-income person. The same is true for liberty and the pursuit of happiness. The American military and other protective agencies and institutions of government exist to protect and preserve these rights for all Americans equally, regardless of how rich or poor they are.
Saying that the progressive tax imposes more heavily on the life and happiness of the wealthy is a hazy philosophical objection and a subjective moral judgment, not a concrete fact. The concepts of "life" and "happiness" are too open ended for that to be the only possible inference one can draw from their inclusion in the Declaration.
Value judgments can't be true or false, since they are primordially positive/negative emotional responses, but they can be authentic (insightful, impartial, sincere) or inauthentic (close-minded, self-absorbed, dishonest). I don't consider the sensibility that a wealthy man's life and happiness are damaged by the progressive tax to be valid, because the sheer magnitude of his wealth, and the opportunities it gives him, ought to continue providing him with a capacity to have the first, and to pursue the second, without added difficulty. It would also add he was only able to engage in economic practices that enabled him to become wealthy because of a social order the government provided for him and the rest of the population. The progressive tax could have very well been an instrumental part of that, particularly if the industry he participates in is supported by subsidies drawn from the incomes of wealthy men participating in other industries.
Furthermore, arguing that the progressive taxation's silence on life or happiness
amounts to a tacit admission of valuing the lower-incomes more than higher-incomes is a straw man. Proponents of the progressive tax don't generally talk about the because, due to their hazy philosophical nature, they are extremely irrelevant. We can't engineer
any policy around a given person's moral sensibilities or their interpretations of Founder's intent, let alone a policy as important as the tax code.
Second, there is no persuasive support in the literature for the claim that higher-income people derive a disproportionately greater value from government protection of property than lower-income people. Some progression advocates have argued that government exists in large part to protect rich people from poor people, while poor people need no such protection. Thus, the value of the rich person’s protection is disproportionately greater than that afforded the poor. Perhaps this was true centuries ago in some feudal nations, but it is not now and never has been generally true in the United States. Others argue that insurance is priced according to risk as well as value, implying that high-value property is at greater risk of loss. While this notion has conceptual merit, it does not follow that property owned by high-income people is at greater risk than property owned by low-income people. In fact, the rich are more likely to engage in self-protection (e.g., build protective walls, install security systems, hire guards, etc.), which would result in reduced, not greater, risk. Seligman, Blum and Kalven, and others have examined the property protection arguments for progression and dismissed them as either untenably weak or without merit.
Some aspects of this objection are viable, particularly the notion that the property of the wealthy is not at greater risk than that of other people, but even that fails to amount to much of an objection when you pause and work it out. However, it misses the true depth of the insurance provided by government -- the government doesn't only
protect value, its very existence plays a major formative role in
creating it. That is to say, the order that government provides is what enables the confidence to engage in productive economic activities. Without government, the self-defense the wealthy engage in would be limited to beating off intruders with clubs, and their wealth would amount to a bigger cave, a larger fire, and a greater store of meat. Because without the order, security, and authentication given by defense forces, contract law, standardized currencies, and continual subsidies, human beings collectively wouldn't have had the confidence to invent and develop complex civilizations.
Third, this interpretation of the benefits principle overlooks the principle of marginal utility. If, as virtually all economists agree, the marginal utility of a dollar of income declines as income increases, then people would place a lower value on protecting their income as it rises. To accept protection theory as an argument for progression, one would have to assert that each additional dollar of income earned is worth more than the previous dollar of income, which is nonsensical.
That's a dishonest play on an economic concept, and ironically is itself nonsensical. The economic utility of individual dollars decreases the more of them you have, but that decline in the value of individual dollars doesn't result in a net loss of value on a person's overall capital. The individual value of a wealthy's man's dollars could drop as low as, say, 10% of a poor man's, but he still has exponentially more value because he possesses so many of them. In order for this objection to have any validity at all, the rich man would have to have less economic value from being rich than the poor man has from being poor, which is where the nonsense comes in.
Fourth, even if the protection argument had merit, it would, at best, argue for a proportionate rather than a progressive tax. To argue otherwise requires a belief that the price of property insurance increases faster than the value of the property (in this case, income), which is observably untrue. If the insurance analogy were applied, those with two times as much income or property would pay two times as much tax, which would be proportionate, not progressive. It’s no accident that “historically almost all exponents of benefit theory employed it to support proportion as against progression.
The problem is that this takes the insurance analogy too literally. There is no way to mathematically evaluate the economic value of the protection government confers because the government, its laws, and order are primordial antecedents to economic activity and the numbers that arise from it, including those of private insurance; the existence and actions of government affect economic value and performance in ways that cannot be evaluated numerically. We can't evaluate the exact economic influence the federal government's Cold War policies had, in the same way we can evaluate and put numerical values on the economic influence of a powerful insurance agency in the free market, because there aren't enough concrete examples for comparison (aka, how would have the economy transformed from the 50s to the 80s without the Cold War?).
We can come up with relative, qualitative, ideas, but the government and its influence over
long periods of time are too large to pin down exact numbers. Far too many uncertain variables affecting far too many businesses and industries.
Note - you can come up with numerical values for government actions on a limited range of policies (aka, subsidizing or not subsidizing that particular industry), but not for its overall presence and administration
over time.
Fifth, the analogy to an insurance company is specious. The costs of the military and police and fire departments are not equivalent to property and casualty insurance, in which the policy is priced in accordance with the value of the property insured. There is no material difference in the cost of protecting persons with high incomes or high-value property than that of persons with low incomes or low-value property. (In fact, the cost might be less, since persons with high income tend to reside in low-crime areas.) Accordingly, there would be no difference in the cost of these protections based on property value. Thus, under the protection theory, the fairest tax system would more logically be per capita.
We don't charge the wealthy more because it costs more to protect a wealthy man than a poor man on an individual basis. We charge them because wealthy men depend more on them (or rather, the order they provide). To be clear, it doesn't cost significantly more to protect a rich man's property from fire than a poor man's property, but the wealthy man suffers a greater loss in value from his $1,000,000.00 house and appliances than the poor man's $500.00 a month apartment and $2,000.00 in appliances.
However, more importantly, the wealth's man wealth and the power it gives him derive economic validity ONLY through the consent and complicity of the community, which they are less likely to give during, say, a socialist revolution; in that case, the money of the wealthy man is no good anywhere (even foreign countries, because the value of the currencies he possesses are devalued by the social unrest of the country he inhabits).