10 THE STATISTICAL VERIFICATION OF 
the real income of wage earners will be neutralized by an 
expansion of population.’ 
In his treatment of the useful and well-known doctrines 
of Economics upon diminishing and increasing returns 
and their relation to price, monopoly, and taxation, 
Pigou remarks that they are results in pure theory. 
* We have made a number of boxes and sub-boxes, 
labelled strong increasing returns, weak increasing 
returns, constant returns, diminishing returns, &c., 
but they are empty boxes and, therefore, some say 
useless except as toys, for we do not know to which of 
them the actual industries of real life belong. Statisti- 
cal technique by itself, in spite of the growing volume 
and improving qualities of the material available, will 
not enable us to accomplish this, for statistics refer only 
to the past. But able business men with a detailed 
realistic knowledge of the conditions of their several 
industries should be able to provide economists with 
raw material for rough judgements. Economists un- 
aided cannot fill their empty boxes because they lack 
the necessary realistic knowledge, and business men 
unaided cannot fill them because they do not know 
where or what the boxes are. With collaboration, 
however, it is not unreasonable to hope that some 
measure of success may eventually be achieved. At 
least, the effort is worth making. It is premature, 
in impatience at the present shortage of straw, to 
scrap our brickmaking machinery. It is the better 
1 This had indeed been one of the ¢ discoveries’ from Charles 
Booth’s inquiry. ‘To one who had been brought up in the 
political economy of Malthus, and taught to believe that every 
increment of income and security would inevitably be accompanied 
by additional children in working-class families, it was disconcert- 
ing to discover that the greater the poverty and overcrowding, 
and especially the greater the insecurity of the livelihood, the 
more reckless became the breeding of children ; whilst every 
increment in income, and especially every rise in the regularity 
and the security of the income in working-class families, was 
found to be accompanied, according to the statistics, by a more 
successful control of the birth-rate.’