ignorance to retard the flow of labor from place to place, or from
industry to industry. A third assumption is the absence of combination
among the workers. A fourth is that of equality of opportunity among the
wage earners; and the absence of barriers of race, religion or sex.

Granted these assumptions, the tendency to equality of earnings for
labor demanding equal skill and effort and performed with equal
efficiency is established. Competition among the workers for employment
and among the employers for workmen would bring this about. Such
differences of wages as would exist would arise from differences in the
nature of the work performed. Thus Adam Smith wrote that "in a society
where things were left to follow their natural course, where there was
perfect liberty, and where every man was perfectly free both to choose
what occupation he thought proper, and to change it as often as he
thought proper" five circumstances would explain "a small pecuniary gain
in some employments, and counter balance a great one in others." These
in his words were: "First, the agreeableness or disagreeableness of the
employments themselves; secondly, the easiness and cheapness, or the
difficulty and expense of learning them; thirdly, the constancy or
inconstancy of employment in them; fourthly, the small or great trust
which must be reposed in those who exercise them; and, fifthly, the
probability or improbability of success in them."[27] All such
differences would be such as "equalize the attractiveness of
occupations" and would be "equalizing differences."[28]

If these assumptions were realized in fact, it would be correct to view
the problem of wages as the study of one set of relationships that
governed a basic level of wages--called the general rate of wages--with
purely supplementary studies of the circumstances governing equalizing
differences. The problem of wages would be a study of forces which were
uniformly influential in relation to the wages of all labor. For all
wages bargains would be governed by them.

In truth, however, practically none of the assumptions underlying the
theory of a general rate of wages are perfectly realized in the United
States to-day, and some of them stand in almost direct opposition to the
fact. It has come about, therefore, that different kinds of labor have
relatively independent economic fortunes. The forces which govern
distribution do not effect them equally. Facts and circumstances which