CHAPTER IV
THE LOGICAL STATUS OF MENTAL FACTORS

Logically, Factors are Principles of Classification.—To the
ordinary student who is new to psychological research, an
attempt to explain factors in terms of analytic geometry
is in most cases an attempt to explain ignotum $er ignotius.
In this country, such a student is more likely to have ap-
proached psychology from the philosophical than from the
mathematical side. Hence he will be able to appreciate
the nature of factor-analysis far more easily if he is shown
its logical origin rather than its mathematical origin.
And, as I have just insisted, its logical nature is, after all, the
more fundamental, although too often that nature is ob-
scured instead of elucidated by the mathematical techni-
calities with which it is commonly expounded.

Let us, then, forget for a moment that the psychologist,
in his effort after precision, puts his factorial specifications
into numerical terms, and let us imagine that a verbal
statement will be sufficient. The so-called factors, as we
have seen, are used because we continually need a few,
permanent, and pregnant concepts by means of which we
can describe both persons and traits. This double mode of
description will, I think, become intelligible enough if we
consider once again a concrete example such as those I have
cited above.

An unknown child is examined at the clinic. The case-
report sums up his physical and his mental characteristics
under separate heads. On the mental side, it describes
first his intellectual (or cognitive) and then his emotional
(or orectic) behaviour. Intellectually he is, let us say,
mentally defective as regards general intelligence, verbal as
regards his special type; and his educational age in each
scholastic test is so and so. Temperamentally, he has high
general emotionality, is of repressed or introverted type,

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