Assume the following:
1. All people have exactly equal talent and capabilities.
2. All markets are perfectly efficient and fair.
3. Return on Investment (ROI) for all occupations is exactly equal, where the definition of "Investment" is non-standard and includes the following:
Note that (b), (c) and (d) have a strong subjective component and even (a) has a significant subjective component via an individualized Discount Rate (a rate of interest that relates the value of future income to current income to a given individual). Because of the differing "Investments" required for various occupations, there would be significant differences in compensation for those occupations since the ROI for all occupations is constrained to be equal.a. Cost (Money & Opportunity Cost) of Education.
b. Difficulty/Stress/Unpleasantness of the job.
c. Negative of the Satisfaction produced by the job.
d. Other similar considerations.
This means that only those occupations that provide adequate value to justify the ROI will exists. In other words, if an occupation requires a great deal of "Investment" and therefore requires a high wage according to the ROI constraint, but nobody is willing to pay for the goods or services that this occupation would provide at that wage level, the occupation won't exist.
The ROI is an after-tax ROI. In this hypothetical world, nobody cares what their compensation is before taxes and instead they focus on their after tax compensation.
Consider the effect of increasing taxes on a given occupation while leaving the taxes on all other occupations the same. It doesn't matter if it's an occupation with high or low compensation, the effect is the same. If everybody with the occupation stayed in it, the after tax ROI for that occupation would be reduced. However, this violates the ROI constraint, so enough people would leave this occupation and do something else until the supply of people working at this occupation is reduced enough so that supply and demand balance to drive the after tax ROI for this occupation back up to nearly its original level.
Since people have left this occupation and are now competing in other occupations, all occupations' ROIs are slightly reduced (including this occupation with its additional tax burden). Taxes and regulation essentially have the effect of reducing our ROI for the work we do.
That's the first interesting effect. All ROIs are reduced by the same amount. Any attempt at making income taxes progressive is completely thwarted. The ROIs for the occupations with the highest and lowest compensations remain equal after the tax increase.
Since the occupation with the new tax burden has similar after tax compensation, the pre-tax compensation must be higher. That means that the production of goods and services dependent on this occupation incur greater cost, which implies that everybody will end up paying a higher prices for these goods and services. Again, any attempt at making income taxes progressive is lost, since everybody, rich or poor, will pay the same increased cost for these goods and services.
In this hypothetical economy, it is impossible for income taxes, regardless how progressive by design, to actually be progressive in effect. Since the poor feel the burden of reduced ROI and higher prices most acutely, the poor feel the burden of higher taxes more than anyone else.
In future posts I'll argue why the real economy bears significant resemblance to this hypothetical economy in regards to taxation.