**By Loet Leydesdorff**

What is the difference between “interdisciplinarity” and “synergy?” Why does it matter? How can indicators of interdisciplinarity and synergy be conceptualized and defined mathematically? Can one measure interdisciplinarity and synergy?

Problem-solving often requires crossing boundaries, such as those between disciplines. However, interdisciplinarity is not an objective in itself, but a means for creating synergy. When policy-makers call for interdisciplinarity, they may mean synergy. Synergy means that the whole offers more possibilities than the sum of its parts. The measurement of synergy, however, requires a methodology very different from interdisciplinarity. In this blog post, I consider each of these measures in turn, the logic underpinning each of them, and I specify the definitions in mathematical terms.