Ideographic explanations are explanations of specific events, phenomenon or behavior which are sought in the careful examination of specific preceding events. For example, Why did Mary murder the butler? Or, What caused World War I? For the most part clinical psychologists and historians are interested in ideographic explanations.
Other disciplines, like sociology, are interested in explanations of classes of events or behaviors and seek these in a careful examination of a few general categories or classes of preceding events. For example, why do men murder their partners? Or, What are the causes of international violence? These explanations are known as nomothetic explanations.
Nomothetic is based on
what Immanuel Kant described as a tendency to
generalize, and is typical for the natural sciences. Nomothetic describes the
effort to derive laws that explain types or categories of objective phenomena.
Idiographic is based on what Immanuel Kant described as a tendency to specify, and is typical for the humanities. Idiographic describes the effort to understand the meaning of contingent, unique, and subjective phenomena.
Idiographic vs. Nomothetic
However the whole issue of whether a trait exists in all people to a greater or lesser degree is complicated by different views of the trait perspective.
Idiographic people have unique personality structures, thus some traits which are cardinal traits are more important in understanding the structure of some people than others.
Nomothetic and idiographic are terms used by Neo-Kantian philosopher Wilhelm Windelband to describe two distinct approaches to knowledge, each one corresponding to a different intellectual tendency.
Nomothetic: people's unique personalities can be understood as them having relatively greater or lesser amounts of traits that are consistently across people.
The Idiographic view emphasizes that each person has a unique psychological structure and that some traits are possessed by only one person; and that there are times when it is impossible to compare one person with others. This viewpoint also emphasizes that traits may differ in importance from person to person (cardinal, central and secondary traits). It tends to use case studies, bibliographical information, diaries etc for information gathering.