Family theories can be distinguished in additional ways. Some theories are relatively abstract and speculative, while others are more concrete and stated in language closer to observable phenomena.
Some family theories are quite general, while others are much more context-specific. General theories are claimed to hold regardless of time or place, or apply to broadly encompassed times and places. Context-specific theories tend to focus on restricted populations, such as one culture or society, the families in one social class, a segment of families with a narrow age structure, one gender, or one racial or ethnic group. Some family theories entail comparisons across contexts, but without covering all of the possibilities. The context of time also varies between family theories. Whether they adopt episodic, biographical, or epochal images of time, most family theories concerned with processes of change carve out a limited span of time for their arguments.
Theories about the family also differ in terms of the breadth of content they cover and which particular subunits within the family are addressed. Theories may be narrow, middle-range, or broad in their content. Relatively speaking, a theory about the effectiveness of communication by husbands is narrow, while a theory of marital quality is middle-range, and a theory of family functioning is broad. In this example, not only does the subject matter become broader with the move from narrow to broad theories, but the relevant units also become broader.
Family theories differ considerably in complexity. Simple theories may involve no more than two or three concepts and two or three relationships among them. Complex theories contain a large number of concepts or variables, and many links exist among the concepts.
Finally, family theories differ according to how coherent a picture of family life they present. Some theories represent families as fairly atomistic collections of elements; scientists understand families if they understand how their elements work, and understanding is impeded if elements are combined that really do not go together. Other theories are more holistic, because they focus on the family as a totality; while families may have elements or features, scientists do not understand how families work unless they see how the features are connected and how these connections produce something unique. Family systems theory is an example of a popular holistic theory (Broderick 1993; Whitechurch and Constantine 1993).
The ways family theories differ in their abstractness, generality, breadth, complexity, and the coherence of their imagery are all matters of degree. While there is much diversity, there also are unifying efforts. Abstract theories can be made more concrete, context-specific theories can be made more general, and complex theories can be simplified, among other possibilities. Part of the ongoing excitement about theorizing in the family field is that there is an endless array of projects for enterprising theorists.