THE LOGICAL STATUS OF MENTAL FACTORS   in
The Fourfold Scheme of Factors and the Fourfold Scheme
of Predicates.—Let us imagine, by way of illustration,^1 a
statistical analysis of the body-measurements of a mixed
group of adults. The results of physical measurement will
be simpler to visualize than those obtained from mental
testing ; and, since the study of temperament has recently
led the psychologist to a renewed interest in physical types,
^1 I have here drawn the parallel between * kinds of factors' and ' heads of
predicables' only for those factors that are obtained by correlating persons.
It would be equally enlightening to the research-worker (though perhaps not
quite so clear to the ordinary student) to attempt the same comparison for
those factors that are obtained by correlating traits. It is far easier to
explain the classification of predicables by taking those predicables that can
be predicated of a concrete individual subject (such as a person) than by
taking those that are predicated of an abstract term or a concrete general
term (such as a trait or a type). This, however, means that I have necessarily
followed the later and more familiar scheme derived from Porphyry (which
was concerned with the former case) rather than the original scheme set
forth by Aristotle (which was confined to the latter case).
Even so, some scholars may question the interpretation of proprium that
I have here adopted to keep the parallel as close as possible. The dispute
as to what is or is not a ' property ' or proprium is by no means uninstructive
to the factorist. It raises problems fundamental to psychology which he
slurs over rather than solves. In the text I have for simplicity adopted the
most literal, though not the most usual, interpretation. I may add that
Aristotle (whose treatment is not quite consistent) himself in certain passages
allows the term cStov to mean ' a peculiarity that distinguishes an individual
from others' (cf. Topics, c, i, I28b, 16 and I29a, 3-5, and Joseph's com-
ments, loc, cit._9 p. 107). Porphyry perhaps would have termed those
attributes summed up in a man's^t specific factor ' his^f inseparable accidents'
rather than his propria* The * properties^J would then be those attributes
which were causally derived from, or necessarily deducible from (which for the
empirical factorist can only mean closely correlated with) the * essential' or
defining factors, i.e. those stating his genus and his species or type.
On the Aristotelian view, everything we can predicate about a subject must
fall under one or other of the heads of predicables. It might therefore be
argued that, instead of identifying predicables with factors only, they ought
also to cover all the traits. Those traits that have saturations for a factor
would then be * properties' deducible from the * essence ' which that factor
specified; and it is interesting to note that Aristotle himself recognized
correlation (or concomitant variation) as a method of proving the relation
(tottos ik rov /xoAAov koll rjrrov. Top. €. viii). The Aristotelian view, how-
ever, would to my mind make too sharp a separation between the factor and
the various traits it comprises. Although for simplicity I spoke at the outset
of n traits, m_v m& , .. %,, as possessing a common characteristic, £, as though
g were an (» + *)th ^tra^^t existing over and above the others (like an * ability '