You're continuing to make out that DMUI is some novel concept that I've just introduced.
This is a standard, widespread concept in economics, even among people who disagree that it should be the basis of the tax code. I am unable to find any mainstream or heterodox economist who disagrees that DMUI is real. The disagreements are about what the implications for taxation (among other things) ought to be.
> I am unable to find any mainstream or heterodox economist who disagrees that DMUI is real.
I agree that DMUI is real. As I've said multiple times. But in attempting to use it as a basis to argue that there is a net increase in value or utility from taking some amount of money from a wealthier individual and giving it to another, less wealthy individual, it's being misapplied.
Attempting to aggregate a subjective, ordinal concept like utility across a group of individuals is, unfortunately, not novel either, but it is incoherent. You're not going to find any political (i.e. mainstream) economists admitting to that, of course, because it undermines the logical basis for their entire profession. However, even mainstream economics these days acknowledges that value is subjective, and the fact that it depends on aggregating metrics which cannot be quantified objectively is a common objection to utilitarian philosophy.
The idea that marginal utility is specific to the individual is hardly novel either. As Herbert Davenport put it in The Economics of Enterprise[0] back in 1913:
> As the human being changes, the utility changes — may become greater or may disappear entirely. [p. 87]
> All utility is relative to the individual. — The foregoing discussion should, by implication, have made it clear that utility and marginal utility and relative marginal utility have to do solely with the particular individual as an account of the way in which he arrives at his purely personal and individual decision to become a purchaser at not more than a particular price — to enter his own demand as one among the great total of demands. Strictly speaking, there is no such thing as the comparison of the utility to one person with the utility to another. Men differ in desires and in the degree and manner in which things appeal or appear to offer service. [p. 97]
Or as Ludwig von Mises explained in The Theory of Money and Credit (1953) on the subject of "Total Value"[1]:
> Value can rightly be spoken of only with regard to specific acts of appraisal. It exists in such connexions only; there is no value outside the process of valuation. There is no such thing as abstract value. Total value can be spoken of only with reference to a particular instance of an individual or other valuing ‘subject’ having to choose between the total available quantities of certain economic goods.
This is a standard, widespread concept in economics, even among people who disagree that it should be the basis of the tax code. I am unable to find any mainstream or heterodox economist who disagrees that DMUI is real. The disagreements are about what the implications for taxation (among other things) ought to be.