23o THE FACTORS OF THE MIND

of the practical teacher, who relies more ^on prolonged
first-hand experience than on precise academic deductions.1
Secondly, the use of the term cause implies, not merely
logical necessity, but physical necessity, i.e. that the action
will be the result of a quasi-physical force, * forced' in the
sense of compulsory. This leads to a still cruder type of
determinism—a type which is far more undesirable, and
certainly more illegitimate, in psychology than elsewhere,
since it persuades us to regard human actions, not merely as
intelligibly determined, but as mechanically determined.
For psychological guidance or treatment it is no doubt
convenient to think of mental growth and intellectual
progress as dependent, at any rate in part, upon certain
constants that remain stable throughout the individual's
life ; and, in view of their correlations with similar features
in other members of that individual's family, it is even
permissible to speak of these constants as (in a rather loose
sense) inherited or innate. The search for factors thus
becomes, to a great extent, an attempt to discover inborn
potentialities, such as will permanently aid or limit the
individual's behaviour later on : and in the results of our
tests we therefore try to sift and separate different hereditary
capacities both from each other and from the effects of

1 It is the combination of the * two-factor theory' of Spearman with the
c biological determinism * of Watson that has led, in the practical applications
of their joint followers, to those rash inferences about individual children
which Mr. J. C. Hill so strongly deprecates (see p. 54 above). Spearman
himself, I believe, has never drawn the sweeping inferences of which Hill
complains. Indeed, it was precisely to escape such criticisms that he intro-
duced the designation g in place of * general intelligence.' But others have
certainly been tempted to forget that a child's 'factor-measurement for
£,' as directly computed from a set of tests, may undoubtedly have been
affected (as Hill suggests) almost as much by " the poverty of his home environ-
ment " and by " the influences of the first five years of life " as by innate or
hereditary conditions. At the same time I see no reason to run to the other
extreme, and declare with Hill that * no conclusions about the distribution
of innate ability can be drawn from the figures * (loc. cit. sup., p. 271). His
own inference is quite as illogical as the inferences he attacks. He might just
as well argue that, because the influence of the sun can never be eliminated
when we are studying the orbit of the moon, therefore no conclusions about
the earth's influence can be drawn from the figures observed. It is the object
of mathematical analysis to separate the two influences so far as possible and
to state the relative weight to be attached to each.