5. The Empiricist Tradition.
The other aspect of
Descartes' thought, the interest in the contents
of con-
sciousness, was developed by both
rationalists and
empiricists alike. The empiricists, like the
rationalists,
were really preoccupied with problems of knowledge.
As
John Locke put it, they were concerned with the
“original,
extent, and certainty” of human knowledge.
They held, however,
that knowledge was based on
experience, not in the unexceptionable sense
that how-
ever we come to obtain beliefs about the world, their
truth or
falsity must be tested by comparing them with
what can be observed, but in
the much more dubious
sense that our ideas about the world
originate in our
own individual sense-experience.
Therefore, questions
about the extent and certainty of knowledge
tended
to resolve themselves into speculations about how ideas
originated; for followers of what was called “the way
of
Ideas” held that genuine ideas must be tracked back
to
impressions of sense. The result was that philo-
sophical questions about the meaning of terms and
about the
grounds of knowledge were systematically
confused with questions in genetic
psychology about
their origin. It was not until the nineteenth
century,
when F. H. Bradley proclaimed that “In England we
have lived too long in the psychological attitude”
(Bradley
[1922], 1, x) that this confusion, which per-
sisted from Locke to James Mill and Alexander Bain,
began to be
systematically exposed.
The net result of this confusion was that the work
of the empiricists
contained both a philosophical the-
ory about the
grounds and acquisition of knowledge
and a psychological theory about the
working of the
mind. The philosophical theory came straight from
Francis Bacon. To obtain knowledge, it was held, a
start had to be made
with simple uninterpreted data,
or impressions of sense. There must be no
premature
hypotheses or “anticipations of Nature.”
Generaliza-
tions had to be made
which reflected regularities in
the data. Bacon elaborated tables of
co-presence, co-
absence, and co-variation of
instances to ensure that
these generalizations were well-founded. These
were
later elaborated by Mill in his celebrated methods of
experimental enquiry. It was of cardinal importance
in this process of
“induction” that generalizations
should not go beyond
the data and that no recourse
should be made to unobservables. Laws
expressed
correlations between what could be observed.
The psychological theory which developed
pari-
passu
with this philosophical theory about the grounds
and acquisition of
knowledge had two main features.
Firstly it maintained that the experience,
thought, and
consequent action of the individual is caused from
without. The environment causes simple ideas (Locke)
or impressions (Hume)
to arise in the individual. The
individual's body was also regarded as part
of the
external world which gives rise to impressions of
reflexion—e.g., of pleasure and pain—which enter the
mind through different types of receptor. (This was
later on called
“the inner environment” by behavior-
ists.) Secondly it was held that the ideas arising
from
these two environmental sources become linked to-
gether by principles of association such as contiguity
and resemblance. Action is initiated by an idea that
has become linked with pleasure or pain. Thus food,
for
instance, gives rise to an idea in the mind, which
has become linked to the
idea of eating, which in its
turn has been linked with the idea of
pleasure. This
brings about the action of eating the food. This
account
of the initiation of action can be found in Hobbes,
though he
did not give much prominence to the associ-
ation of ideas in his account of thinking. He stressed
the
importance of plans deriving from desire.
The history of empiricism is largely the history of
the elaboration and
sophistication of these basic ideas.
In the philosophical and
methodological sphere there
were three main derivative doctrines. Firstly
the notion
of “data” was gradually sophisticated into
modern
theories of sense-data, which can be found in the work
of
philosophers such as G. E. Moore, Bertrand Russell,
and A. J. Ayer. In the
scientific sphere Kant did much
to popularize the idea that the domain of
science was
coextensive with the domain of the measurable. It
became
important, therefore, for scientists to obtain
data which were as precise
and pure as possible by
devising various forms of measurement. In
psychology
the nineteenth-century concentration on psycho-
physics, stemming largely from the
work of Weber and
Fechner, bore witness to this search for measurable
data—the notorious just noticeable differences.
Secondly, a theory of meaning developed which has
come to be known as
“logical empiricism.” This main-
tained that only those terms are strictly meaningful
that can be cashed by reference to what can be ob-
served. The language of morals and of poetry is, strictly
speaking, meaningless (or has merely “emotive mean-
ing”) because it cannot be tied down in this
way to
observables. Scientific terms have either to be “opera-
tionally defined” or
related indirectly to observation
by a process of “logical
construction.” In the early
twentieth century P. W. Bridgman's
book The Logic
of Modern Physics (1927) popularized
this view of
scientific terms. Its leading ideas were applied to psy-
chology by C. C. Pratt in The Logic of Modern Psy-
chology (1939) and exerted a considerable influence on
B.
F. Skinner, a leader of modern behaviorism.
The third development was the attempt to formulate
precisely the methods for
arriving at well-founded
generalizations and to get clearer about the
theory of
probability which was presupposed. The works of J. S.
Mill,
W. E. Johnson, and J. M. Keynes were classics
in this tradition.
The psychological theory which was favored by most
of the empiricists was
given an ambitious start by
David Hume who pictured himself as the Newton
of
the sciences of man. Simple impressions were regarded
as mental
atoms and the principles of association were
postulated as performing, in
the mental sphere, the
same function of uniting them together as was per-
formed by the principle of gravitational attraction
in
the physical sphere. David Hartley developed an even
more ambitious
version of this type of theory; for he
held that the psychological
principles of association
paralleled the mode of operation of
physiological
disturbances in the substance of the nerves, spinal
marrow, and brain, which he called “vibrations.” It
was left to James Mill, however, to free associationism
from Newtonian
pretensions and physiological specu-
lation
and to attempt to formulate soberly and prosa-
ically the basic principles in terms of which ideas were
thought
to be connected. Most of the subsequent work
in the nineteenth century of
the British associationist
school consisted in criticism, refinements, and
simpli-
fications of Mill's edifice.
In France, largely through the infectious cynicism
of Voltaire, British
empiricism came to exert an in-
fluence that
was more mundane, and less theoretical.
It encouraged thinkers to observe
more carefully and
more objectively how men in fact behaved. Diderot's
Lettre sur les aveugles and Lettre sur les sourds et muets
were classics of their
kind—concrete case studies of
individual lives. Similarly
Condillac approached
Locke's problems in a more concrete, if more imagina-
tive way, by creating the fiction of
a statue endowed
only with the faculty of smell. And Cabanis, a vehe-
ment critic of Condillac, began his
psychophysiological
writings in 1795 with an attempt to answer the con-
crete, if depressing question, of whether
the victims
of the guillotine suffer any pains after decapitation.
His
theory, which attacked Condillac's starting point
of imagining a being
capable of sensation in isolation
from the structure of the organism as a
whole, was
diametrically opposed to the atomism of the associa-
tionist tradition. But it was a
theory based on actual
observations of men from childhood to maturity.
Simi-
larly, La Mettrie, who elaborated
Hobbes's thesis that
man is a superior type of machine, developed his the-
ory not as an imaginative extrapolation from
Galilean
mechanics but partly as a result of his medical studies
under
Hermann Boerhave, and partly from direct ob-
servation of his own experiences during a fever. And
in the
nineteenth century Taine, who represented very
much the antimetaphysical,
positivistic school in
France, scrambled together, in his De l'intelligence
(1870; trans. as On the Intelligence, 1871), reports from
asylums,
physiological facts, and references to Mill's
Logic!
It would be tempting to suppose that this interest
in the concrete behavior
of men, and the attempt to
study it objectively, which was so
characteristic of
French empiricism, was one of the formative
influences
in the development of behaviorism. There is, however,
little plausibility in this suggestion. For the rise of
behaviorism is to be explained partly as a method-
ological reaction to introspective psychology and
partly as a consequence of the success which was being
attained in the
study of animals. Almost the last thing
which the behaviorists actually
came to study was the
concrete behavior of men. Let us now pass,
therefore,
to the immediate origins of behaviorism.
