This paper proposes a way of incorporating fuzzy temporal reasoning within
diagnostic reasoning. Disorders are described as an evolving set of necessa
ry and possible manifestations. Ill-known moments in time, e.g., when a man
ifestation should start or end, are modeled by fuzzy intervals, which are a
lso used to model the elapsed time between events, e.g., the beginning of a
manifestation and its end. Patient information about the intensity and tim
es in which manifestations started and ended are also modeled using fuzzy s
ets. The paper discusses many measures of consistency between the patient's
data and the disorder model, and defines when the manifestations of the pa
tient can be explained by a disorder. This work also discusses related issu
es such as the intensity of manifestations and the speed in which the disor
der is evolving, given the patient's data, and how to use that information
to make predictions about future and past events.