ELASTICITY OF SUPPLY AS A DETERMINANT OF DISTRIBUTION 73 
would be only a small share of what it is now; while still others 
have reasoned that since without labor, the product would be 
nil, labor should receive all. Others have said that capital should 
receive the difference between what would be produced without 
its services and what is produced and hence should obtain vir- 
tually all of the product. If this interpretation of marginal 
productivity were followed, there would of course be claims 
(including that of land) upon the national product, of nearly 
four times the product itself. The truth of the matter is of 
course that all the factors coOperate in turning out the total 
product but that their return per unit depends upon the amount 
of change in the total product which the last of their constituent 
units occasions when all other factors are held constant. 
There is a further feature of the marginal theory which needs 
exploration. Does the sum of the returns of the two factors (i.e., 
the respective marginal productivities of each multiplied by their 
number of units) equal the total product minus rent? This has 
been much disputed. Hobson * and Adriance ® declare that it 
does not and urge that the output specifically attributed to the 
last worker was really the result of the coOperation of the total 
number of workers and the capital equipment. To try to sepa- 
rate the contributions of individuals would be impossible and 
would lead to double counting. This criticism can be and has 
been mathematically disproved by the late P. H. Wicksteed * and 
by C. W. Cobb of Amherst College * by the application of Euler’s 
law and on the assumption that the total output will increase in 
the same proportion as equal proportionate increases in the supply 
of the factors. Where the increase in the total product is not 
linear however the sum of the amounts attributable under 
marginal productivity may not be equal to the whole.’ 
The theory of marginal productivity as formulated by Pro- 
fessor Clark measured productivity in terms of physical units. 
Yet since many commodities are produced, it is clearly necessary 
* J. A. Hobson, Economics of Distribution, p. 147. Hobson, however, has 
never understood the principle of infinitesimal differences which lies at the 
base of the theory. 
*W. M. Adriance, “Specific Productivity,” Quarterly Journal of Eco- 
nomics, Vol. XXIX, p. 158. 
* Wicksteed, A Coordination of the Theories of Production and Dis- 
tribution, pp. 1-56. 
* See J. M. Clark, The Economics of Overhead Cost, p. 473. 
rd But oe Wicksteed, The Common Sense of Political E¢onomy, pp. 358 ff.