rrence after the panic of
1907, when various organized groups of wage earners made common cause to
resist wage reductions even for unskilled and unorganized labor. Such
mutual aid plays its part in determining the wage levels of the
different groups of wage earners.

This concludes the explanation of the forces which govern the relative
wage levels of the separate groups or classes of labor. The actually
existing differences of earnings between different groups of labor can
only be explained by the combined influence of all the forces discussed.

7.--Differences in the levels of earnings of various groups of wage
earners have been called "differentials." An effort has been made to
explain their causes. Several practical conclusions, in regard to them,
may be deduced from the preceding discussion.

Firstly, that these differentials (which may be measured by the
differences between the average earnings of various occupations) result
from, and in that sense represent, a large variety of actual forces;
some of which can only be changed slowly and with much effort, as, for
example, the relative plenty of the lowest grades of labor. As complete
a knowledge as is obtainable of the various forces which produce these
differentials is absolutely necessary to any project of wage regulation.

Secondly, although they represent a large variety of actual forces, it
is misleading to apply such adjectives as "normal" or "natural" to them.
For such adjectives inevitably suggest that the condition to which they
are applied corresponds to a set of facts from which divergence can be
only temporary, and is probably accidental. That, however, is not true
in regard to the wage differentials which exist at any given time.

Thus, and thirdly, in any project of wage regulation, existing wage
differentials can neither be accepted nor rejected blindly. A policy of
wage settlement for industrial peace need not be based upon the
acceptance and maintenance of all existing differentials. On the other
hand, whatever revisions are undertaken should rest upon a knowledge of
the forces which have established existing differentials. The policy of
the South Australian Industrial Court, as expressed by its President,
would seem to be a practical application of this view. To quote from one
of his decisions: "Preexisting or customary marginal differences are
followed by this court as a prima facie rule, but the rule is only prima
facie, and is subject to