2Q 8 THE MISMEASURE OF MANcannot be attributed to "decrease in the supply of the general psy-
cho-physiological energy," but must represent a build up of toxins
that act selectively upon certain kinds of neurons. Fatigue, Spear-
man proclaimed, "primarily concerns not the energy but the
engines" (1927, p. 318).
Yet, as we find so often in the history of mental testing, Spear-
man's doubts began to grow until he finally recanted in his last
(posthumously published) book of 1950. He seemed to pass off the
theory of energy and engines as a folly of youth (though he had
defended it staunchly in middle age). He even abandoned the
attempt to reify factors, recognizing belatedly that a mathematical
abstraction need not correspond with a physical reality. The great
theorist had entered the camp of his enemies and recast himself as
a cautious empiricist (1950, p. 25):
We are under no obligation to answer such questions as: whether "fac-
tors" have any "real" existence? do they admit of genuine "measurement"?
does the notion of "ability" involve at bottom any kind of cause, or power?
Or is it only intended for the purpose of bare description? ... At their
time and in their place such themes are doubtless well enough. The senior
writer himself has indulged in them not a little. Duke est desipere in loco [it
is pleasant to act foolishly from time to time—a line from Horace]. But for
the present purposes he has felt himself constrained to keep within the
limits of barest empirical science. These he takes to be at bottom nothing
but description and prediction.... The rest is mostly illumination by
way of metaphor and similes.
The history of factor analysis is strewn with the wreckage of
misguided attempts at reification. I do not deny that patterns of
causality may have identifiable and underlying, physical reasons,
and I do agree with Eysenck when he states (1953, p. 113): "Under
certain circumstances, factors may be regarded as hypothetical
causal influences underlying and determining the observed rela-
tionships between a set of variables. It is only when regarded in this
light that they have interest and significance for psychology." My
complaint lies with the practice of assuming that the mere existence
of a factor, in itself, provides a license for causal speculation. Fac-
torists have consistently warned against such an assumption, but
our Platonic urges to discover underlying essences continue to pre-
vail over proper caution. We can chuckle, with the beneficence of
hindsight, at psychiatrist T. V. Moore who, in 1933, postulated def-