A 
STATISTICAL METHOD FOR MEASURING “MAR- 
GINAL UTILITY” AND TESTING THE JUSTICE 
OF A PROGRESSIVE INCOME TAX 
Irving Fisher 
Introduction 
Amona Professor J. B. Clark’s many contributions to economic 
science is his discovery, independently of Jevons, Menger, and 
Walras or their anticipators, of the concept of “Marginal Utility,” 
or as he first called it “effective specific utility,” or as I shall call 
it in this article, “want-for-one-more” * unit of any economic 
good. He is the only American who has that honor. 
The basic importance of this concept has been partially lost 
sight of because of the growth of statistical economics and 
the lack hitherto of any method of showing that such a purely 
psychical magnitude is at least capable of being measured, 
granted the necessary data. 
For a generation, economic text books have displayed curves 
purporting to show “the law of diminishing utility.” But how 
'1 have discussed the unsatisfactory terminology on this subject in “Is 
‘Utility’ the Most Suitable Term for the Concept Which It is Used to 
Denote?”, American Economic Review, Vol. VIII, No. 2, June 1918, pp. 
335-337. Among the terms in use or proposed—utility, desiredness, desir- 
ability, ophelimity, advantage, rarete, wantedness, wantability, want—I 
prefer the short and simple term “want” followed by “for.” To relieve 
monotony, occasional use may be made of “wantability of,” or, more 
strictly, “wantedness of.” When, as is usually the case, we refer to what 
is commonly called the “margin,” I suggest we say not marginal want but 
simply “want-for-one-more,” or, to relieve the monotony, ‘“wantability- 
of-one-more” or “advantage-of-one-more” rather than “final degree of 
utility” or even “marginal desirability.” Although “margin” and ‘“mar- 
ginal” are already in current use, their technical meaning is not self-evident. 
I find intelligent business men assuming that “margin” refers not to an edge 
or limit but to an interval as the “margin” of a page or the “margin” in a 
broker’s acccount. I hope the term “utility” in particular may be 
abandoned, because it has to-day other economic connotations, such as 
in “A Public Utility” referring, say, to a telephone company, and because 
it seems to imply a committal to the old utilitarian “calculus of pleasure 
and pain” of Bentham and his school. The true meaning needed is based 
primarily not on pleasure but desire. For a fuller statement see my 
“Mathematical Investigations in the Theory of Value and Prices,” Trans- 
actions of the Connecticut Academy, Vol. IX, July 1892, pp. 1-124, repub- 
lished 1925, Yale University Press. 
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