METAPHYSICAL STATUS OF FACTORS 219

proposed, and not that the whole idea of faculties springs
from a crude and obsolescent notion of scientific explanation.
Factor-analysis, I believe, owes much of its present con-
fusion to the fact that most psychologists still tacitly assume
that, if faculties do not exist, mental factors must be
invoked to fulfil their explanatory functions.

The causal phraseology, which almost every f actorist continues to
employ, implies a naive and popular view of the nature of mind.
The minds of the persons tested are conceived as individual sub-
stances ; and the * abilities' inferred are then pictured as causal
properties inherent in those substances. The underlying motive
is not hard to discern. If we wish to predict a future condition
from the present, we seem compelled to assume some principle of
constancy or conservation, an entity permanent enough at least to
last until the date to which our predictions refer ; and by the
unsophisticated thinker such a principle is nearly always visualized
concretely as an enduring substance or as part of such a substance.
Yet even in explaining physical phenomena, the hypothesis of
individual substances possessing causal properties or attributes
would scarcely pass unchallenged by the metaphysician : and in
psychology, where we are no longer dealing with separable bodies of
matter, but, for all we know, merely with certain aspects of the
working of the nervous system and its adjuncts, such a way of
speaking is even less permissible than in other fields of science. It
manifestly begs a host of unsolved metaphysical issues.

Philosophers and psychologists alike have continued to
suppose that science must aim primarily at discovering
causes, although as a matter of fact the word * cause'
vanished long ago from the vocabulary of the more advanced
of the sciences. The philosopher regards causality as a
weakness of physical science ; the psychologist, as its special
strength. Yet nowadays in the physicist's account of
gravitation there is nothing that can be called either a cause
or an effect: there is only a quantitative law embodied in
a mathematical formula. Already by the end of the nine-
teenth century,1 causal interpretations in physics were

1 The extrusion of causality from physical science was virtually accom-
plished by writers like Kirchhoff and Mach abroad and Karl Pearson in this
country. With the general recognition that force and components of
force are mere mathematical fictions, causality disappeared. It lingered
longest in physical dynamics, and still persists in the psycho-dynamics of