THE LOGICAL  STATUS OF MENTAL FACTORS     97
repressive rather than an aggressive character, and an
unpleasant rather than a pleasant feeling-tone, we are not
merely defining those emotions : we are classifying them—
classifying them according to a hierarchy of subordinated
and dichotomous principles (cf. p. 19). What distinguishes
factor-analysis, therefore, from other ways of discovering
how individuals and their numerous attributes can best
be classified is chiefly this : whereas the ancient logician
reached his definitions by examining the meanings of words,
the modern factorist reaches his classifications by examining
the correlations between the forms of behaviour to which
those words very loosely refer. But the ulterior object is
still the same ; and, whether we are describing persons or
traits, the factorial concepts adopted are simply principles
of classification.
There is, however, a second peculiarity of factor-
analysis : but this, from the logical standpoint, is only
incidental. Factor-analysis, as we have seen, is quantita-
tive. One of the first problems of any science as we under-
stand it to-day is to devise a means for converting qualitative
specifications into quantitative. The process by which the
psychologist achieves this translation will more easily be
understood if we think once again of the analogous but
more concrete problems that arise in navigation or geo-
graphy : there, too, the numerical determinations of the
expert have arisen simply by progressive refinement of the
cruder qualitative classifications of the plain man.
From the time of Aristotle to that of Bacon, primitive science was
content with the simple classificatory procedure, such as the
traditional logic continued to employ. The transition from
classification in terms of qualitative attributes to measurement in
terms of quantitative variables was mainly accomplished by
physical science during the sixteenth century. Mental science, we
are told, has still to complete the change " from the Aristotelian to
the Galilean viewpoint." ^x But even in dealing with the physical
world the plain man rarely thinks in terms of measurement.
^1 K. Lewin, Dynamic Theory of Personality. By the " Galilean viewpoint"
seems to be understood the standpoint of experimental and mechanical
science. The mechanical and dynamical interpretation, however, would
appear to have been a secondary consequence of the more accurate ideas of
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