CHAPTER II

FACTORS ARE VARIOUSLY USED FOR DESCRIPTION,
PREDICTION, OR CAUSAL FATLANATION

(I) Description.—Primarily the figures that specify the
psychologist's factors, like those that specify his correlations,
are simply numerical constants, descriptive of the sample
he is investigating at the moment. But it will at once be
asked, if mere description is his immediate aim, why does
he go out of his way to express it in terms of abstract
hypothetical concepts, like, g, v, p9 and the rest, instead of
by the concrete and familiar processes he has actually
tested, such as reading, spelling, or arithmetic f The
motive is usuallyx said to be economy—4 a desire for
simplification/ " Entities," we are constantly reminded,
" should not be multiplied beyond necessity " j and the
use of factors will enable us to cut down the number of
our working concepts. I would rather describe the under-
lying purpose as c orderly simplification * : the effort to
economize labour and thought is to my mind secondary
to the endeavour to make things intelligible, to * bring order
out of chaos/ The task of science is to organize ideas
rather than to minimize them.

The analysis of correlations fulfils the same end for the
multi-variate universe as the analysis of a frequency-

1 Cf. Guilford, 1936, Psychometric Methods, p. 457, ** Science * , , wants
to know what is the least possible number of concepts with which one can
order and describe the multiplicity of phenomena*" " Both practical
necessity and the desire for theoretical simplification lead one to seek for si
few tests which will describe the individual * « . Such tests might then be
said to measure the factors of the mind " (Thomson, be. cit*9 p. 4). " The
decision may be made on the ground that we should be parsimonious"
(loc. cit., p. 15). Similarly Thurstone asks: " What is the minimum number
•of factors Uiat will account for the observed intercorrelations ? *' (kc. dt^
p. 150) j for he too maintains that" the chief object of science is to minimke
mental effort " (p, 45).

*4