Interdisciplinary and disciplinary identities: towards a theory of forms of knowledge change

The concept of interdisciplinarity lacks theoretical understanding, and consequently, the number of indicators for interdisciplinarity is booming: out of field citations, betweenness centrality, or the set coherence, diversity, mediation, to mention a few. However, these indicators focus on characteristics of papers and journals, without referring clearly to the processes of knowledge production, communication and stabilization. Without understanding of the nature of interdisciplinarity and its various forms, the choice of indicators seems rather arbitrary. In this paper we argue that interdisciplinarity is one of the forms of development of research fields. We will show that interdisciplinarity is a temporary phase in knowledge dynamics. New fields emerge at the boundaries of existing fields as multidisciplinary research activities, and either develop through an interdisciplinary phase into a new discipline, or remain multidisciplinary for a while and generally disappear.\n\nWe use the analysis of journal-journal citation relations to map the identity and development of disciplinary, multidisciplinary and interdisciplinary research fields. A comparison results in three types of identities: (1) disciplinary fields, (2) interdisciplinarity as a developmental phase from multidisciplinary to disciplinary fields, and (3) unstable temporal multidisciplinary research topics at the boundaries between research fields. We conclude that the main difference between a mature interdisciplinary field and normal disciplinary fields is that the former is newer than the latter. We propose to focus on change in the research landscape, instead of on indicators for what is only one (early or long term unstable) stage of interdisciplinarity. The mapping approach can be used to identify the nature of cognitive change in general, such as the emergence, growth, differentiation, merger, and decline of research fields.