Dyadic measures of democracy face an unresolved problem of aggregating two parties’ scores.

Evidence

The literature on the demo­ cratic or liberal peace has focused on the hypothesis that democracies do not fight wars with each other. This literature—along with the in­ ternational conflict literature in general—must deal with the problem of concept structure because international conflicts have two or more parties. The question arises about what should be the concept of say, democracy, for a dyad. We have democracy scores for each party to the conflict, but it is not clear how to aggregate the democracy scores of the two parties to construct a measure for the dyad as a whole. Hence we have the same problem as in structuring the secondary-level di­ mensions to form the basic-level concept. — Gary Goertz, Social Science Concepts, 59

Categorization

• QUESTION: Is there any non-arbitrary aggregation rule for dyads, or does every choice smuggle in a substantive theory of war?
• SEED: An essay on how “the dyad” hides a measurement choice that quietly decides the democratic-peace debate — aggregation as theory, not housekeeping.