objectivity means that, given a description of what was done in a partic-
ular experiment, any scientist could repeat it and obtain essentially the same
results, at least within the limits of measurement error. By this criterion, intro-
spective studies of the qualities of perceptual experience were unscientific be-
cause they were not objective. Two different people could perform the same
experiment (using themselves as subjects, of course) and report different expe-
riences. When this happened—and it did—there was no way to resolve dis-
putes about who was right. Both could defend their own positions simply by
appealing to their private and privileged knowledge of their own inner states.
This move protected their claims but blocked meaningful scientific debate.
According to behaviorists, scientists should study the behavior of organisms
in a well-defined tas ksituation. For example, rather than introspect about the
nature of the perception of length, behaviorists would perform an experiment.
Observers could be asked to discriminate which of two lines was longer, and
their performance could be measured in terms of percentages of correct and
incorrect responses for each pair of lines. Such an objective, behaviorally de-
fined experiment could easily be repeated in any laboratory with different sub-
jects to verify the accuracy and generality of its results. Watson’s promotion of
objective, behaviorally defined experimental methods—calledmethodological
behaviorism—was a great success and strongly shaped the future of psycho-
logical research.
Of more relevance to the philosophical issue of the relation between mind
and body, however, were the implications of the behaviorist push for objectiv-
ity in theoretical constructs concerning the mind. It effectively ruled out refer-
ences to mental states and processes, replacing them with statements about an
organism’s propensity to engage in certain behaviors under certain conditions.
This position is often called theoretical behaviorism or philosophical behavior-
ism. Instead of saying, ‘‘John is hungry,’’ for example, which openly refers to
a conscious mental experience (hunger) with which everyone is presumably
familiar, a theoretical behaviorist would say something like ‘‘John has a pro-
pensity to engage in eating behavior in the presence of food.’’ This propensity
canbemeasuredinavarietyofobjectiveways—suchastheamountofacer-
tain food eaten when it was available after a certain number of hours since the
last previous meal—precisely because it is about observable behavior.
But the behaviorist attempt to avoid talking about conscious experience runs
into trouble when one considers all the conditions in which John might fail to
engage in eating behavior even though he was hungry and food was readily
available. Perhaps he could not see the food, for example, or maybe he was
fasting. He might even have believed that the food was poisoned. It might seem
that such conditions could be blocked simply by inserting appropriate provi-
sions into the behavioral statement, such as ‘‘John had a propensity to engage
ineatingbehaviorinthepresenceoffood,providedheperceivedit,wasnot
fasting, and did not believe it was poisoned.’’ This move ultimately fails, how-
ever, for at least two reasons:
1.Inability to enumerate all conditionals. Once one begins to thin kof con-
ditions that would have to be added to statements about behavioral dis-
positions, it quickly becomes apparent that there are indefinitely many.8 Stephen E. Palmer