560 TRANSACTIONS OF SECTION PF. 
Section F.—KCONOMIC SCIENCE AND STATISTICS. 
PRESIDENT OF THE SEcTION.—Rey. Puitiep H. WicksTEep, M.A. 
THURSDAY, SEPTEMBER 11. 
The President delivered the following Address :— 
The Scope and Method of Political Economy in the Light of the 
“ Marginal’ Theory of Distribution.? 
Tue subiect on which I désire to address you this morning is the bearing of 
what is known as the ‘marginal theory of distribution’ upon the scope and 
method of economic study. 
I address myself primarily to those who already accept this theory, inviting 
their attention to the modifications it is already introducing into current 
conceptions of Political Economy and its relation to other studies, and urging 
tne necessity of accepting the change more frankly and pressing it further. 
But at the same time I think we shall find that the best approach to our 
proper subject is through a summary exposition, if not a defence, of the theory 
itself. 
To begin with, then, the marginal theory of distribution rests upon a theory 
of exchange value. This latter theory is very easily stated in mathematical 
language; for it simply regards value in exchange as the first derived or 
‘ differential ’ function of value in use; which is only as much as to say, in 
ordinary language, that what a man will give for anything sooner than go 
without it is determined by a comparison of the difference which he conceives 
its possession will make to him, compared with the difference that anything he 
gives for it or could have had instead of it will or would make; and, further, 
that we are generally considering in our private budgets, and almost always in 
our general speculations, not the significance of a total supply of any com- 
modity—coals, bread, or clothes, for instance—but the significance of the 
difference between, say, a good and a bad wheat harvest to the public, or the 
difference between ten and eleven loaves of bread per week to our own family, 
or perhaps between ten days and a fortnight spent at the seaside. In short, 
when we are considering whether we will contract or enlarge our expenditure 
upon this or that object, we are normally engaged in considering the difference 
to our satisfaction which differences in our several supplies will make. We 
are normally engaged, then, not in the consideration of totals, either of supplies 
cr of satisfactions, but of differences of satisfaction dependent upon differences 
of supplies. 
According to this theory, then, what 1 am willing to give for an increase 
in my supply of anything is determined by the difference it will make to my 
satisfaction, but what I shall have to give for it is determined by the difference 
it would make to the satisfaction of certain other people, for if there is anyone 
to whom it will make more difference than it will to me, he will be ready 
2 This Address in a revised form, and with diagrams illustrative of the theory 
of the market, will appear in the Hconomic Journal for March 1914. 
