3. C. L. Hull.
Behaviorism was basically old philos-
ophy masquerading as a new scientific theory. In the
1930's
philosophers began to be extremely critical of
the old inductivist view of
scientific method, which
most of those in the empirical tradition had
accepted,
though Whewell in the nineteenth century had been
an acute
critic of this view. The role of hypothesis
and deduction in science, which
had been so prominent
in the work of Galileo, was emphasized.
Psychology
began to be influenced by this change of emphasis in
the
philosophical climate. It was suggested, notably by
Kurt Lewin and by Clark
Hull, that psychology was
in a state of disarray, split into warring
factions, be-
cause it had not yet entered its
Galilean phase. Lewin,
a Gestalt psychologist, wrote a detailed
methodological
polemic to this effect in his chapter on
“Aristotelian
and Galilean Modes of Explanation” in
his A Dynamic
Theory of Personality (1935). He
envisaged the use of
the resoluto-compositive method of Galileo to
erect
a field theory in psychology employing postulates taken
from
dynamics.
Clark Hull, unlike other prominent behaviorists, was
not trained in an
animal laboratory. He had established
a reputation for himself as an
ingenious and talented
designer of experiments in concept formation, hypno-
sis, and suggestibility. He next turned to
Pavlov's laws
of conditioning, and Hull's love for mathematics led
him
to set up a hypothetico-deductive model of learn-
ing. He became more and more ambitious and revived
Hobbes's dream of
a mechanical system in which the
laws of human behavior could be deduced
from postu-
lates about “colorless
movements” at the physiological
level. He accepted Tolman's
distinction between mo-
lecular and molar
behaviorism, but differed from
Tolman in thinking that behavior at the
molar level
could ultimately be explained in terms of movements
at the
molecular level. In 1943 he set out his ambitious
program in his
Principles of Behavior, and in 1951 he
published a
revised and more formalized version of his
system in his
Essentials of Behavior.
There was little original in the actual content of
Hull's system save the
appearance of exactitude created
by his technical constructs and
mathematical form of
expression. Hull started from the biological
postulate
of self preservation and maintained that the organism
is in
a state of need when there is a deviation from
optimum conditions for
survival, e.g., lack of food,
water, air. These needs are reduced by
adaptive ac-
tions. The pattern of actions which
lead to a reduction
of a need becomes reinforced—as in
Thorndike's law
of effect. A stimulus which leads to a need-reducing
action may become associated with another stimulus
in accordance with
principles of conditioning, though
Hull believed that there is no
conditioning without
need-reduction.
Hull acknowledged the importance of what Tolman
had called
“intervening variables” in theory con-
struction, and also took over his concept of
“drive.”
He regarded needs as producing primary
animal drives,
which enabled him to correlate observable antecedent
conditions—e.g., of food deprivation with the energy
expended in
behavior, e.g., in eating. He classified
drives on the Darwinian principle
of whether they
tended towards survival of the individual organism or
of the species. Whereas, however, Tolman only postu-
lated such drives in order to explain the activation of
behavior
patterns, Hull postulated them to explain
their acquisition as well, and
their consolidation into
habits. Tolman, as has already been explained,
was
critical of the law of effect. Hull, on the other hand,
tried to
provide a mechanical theory to explain its
operation. He also rejected
Tolman's emphasis on cog-
nitive variables and
claimed that they could be derived
from his fundamental postulate of
stimulus-response
association. Like Watson he was basically a periph-
eralist and an associationist in his
orientation. He
merely attempted to formulate these assumptions more
precisely as part of a mechanical system.
Hull said that his book had been written “on the
assumption that
all behavior, individual and social,
moral and immoral, normal and
psychopathic, is gen-
erated from the same
primary laws; and that the
differences in the objective behavioral
manifestations
are due to the differing conditions under which habits
are set up and function” (Principles of Behavior,
Pref-
ace, p. v). This was programmatic. In fact
his defini-
tions and postulates were not
well rooted in physio-
logical findings,
and precise deductions to the level of
motor behavior were never
made—if indeed they ever
could be made. Unobservables, such as drive-stimuli,
drive-receptors, etc., which were meant to fill in the
mechanical picture
of the workings of needs and drives,
functioned more as hypothetical
constructs relating to
entites whose existence was shadowy and whose inter-
relations were highly obscure. The
main value of his
work was to formulate assumptions about animal
learning at the motor level in a precise enough way
to be refutable. And
most of his assumptions were in
fact refuted, e.g., by Hebb, Young, Harlow,
and others.
His system, however, became popular. Needs and
acquired
drives proliferated which lacked even the
pretence of being anchored to
physiological moorings
(Peters [1958], Chs. 4 and 5). Drive-reduction
became
a classic example of twentieth-century metaphysics.
