Fundamental Postulate and Corollaries

Kelly claimed that constructs operate according to a fundamental postulate.
This postulate maintains that each person directs thoughts and cognitions
in a way that permits the most accurate prediction of future events. If a
woman has a personal construct which states that her boyfriend is a thoughtful
person, and he sends her flowers while she is in bed with the flu, her construct
would be regarded as an accurate one. If, however, that same boyfriend
used her illness as an opportunity to date other women and ignored
her illness in the process, it would be necessary to adjust her construction
system because it does not accurately predict her boyfriend’s behavior. This
process of changing one’s construction system in order to predict future
events more accurately is an ongoing one, designed to decrease uncertainty
in the future.

While the fundamental postulate is critical to Kelly’s attempts to predict
and explain behavior, it is not sufficient to cover all aspects of a person’s behavior
and the choices that are made which cause that behavior. In order to
address this additional detail, Kelly provided a series of eleven corollaries to
his fundamental postulate. These corollaries are supporting statements that
provide a detailed analysis of thoughts and behaviors which cannot be directly
derived from the fundamental postulate.

The construction corollary maintains that people continue to learn as
they are presented with similar events in life. For example, if a man’s mother
has given him a birthday present for the last thirty years, his prediction that
he will receive another present from her on his next birthday makes sense.
Similarly, if one has watched a particular television program at 11:30 p.m. on
weeknights for the past several years, one’s prediction that it will again be on
television at the same time next Monday night is a reasonable one.
Another important corollary to Kelly’s fundamental postulate is the dichotomy
corollary. This states that all constructs consist of pairs of opposites.
That is, a college course may be either interesting or uninteresting, but
it cannot be both at the same time. One important aspect of the dichotomy
corollary is that each construct must include three members or items, with
two of the members having the same characteristic and the third member
having the opposite characteristic. For example, breathing and not breathing
would not be a legitimate construct in evaluating three friends. Because
all of them breathe, the proposed construct would not tell how the three individuals
are different as well as alike. Therefore, it would not reduce uncertainty
in the future.

A third corollary to Kelly’s system which is particularly important is the range corollary. This maintains that a construct is only relevant in dealing
with a finite number of events. The events for which a construct is deemed
applicable is called its range of convenience. Terms such as “happy” and
“sad” would not be within the range of convenience in depicting the characteristics
of a tree or a book, while they might be critical in evaluating one’s
relatives.
Varying degrees of applicability can be found within a series of constructs.
For example, the construct “kind versus cruel” would be more relevant
in evaluating a relative or girlfriend than it would be in considering the
qualities of an elevator operator one occasionally encounters. Kelly’s fundamental
postulate and supporting corollaries provide considerable information.
The theory also provides some interesting applications in terms of personality
assessment and therapeutic intervention. 598