How to ‘measure’ ideas: Introducing the method of cognitive mapping to the domain of ideational policy studies

Decades of study have greatly improved our understanding of the role of ideas in policy-making. General knowledge accumulation, however, has been slow, which may be caused by the limited availability of methods designed to study ideas. This article introduces the method of cognitive mapping (CM) and argues its value for ideational policy sciences. It starts with an overview of the methodological debate in the literature and methods in use, culminating in five requirements a method to analyze ideas should fulfil. Subsequently, the CM technique is introduced. Using a map of the Dutch Prime Minister Rutte and Central Bank Governor Knot, the article shows CM to fulfil four of the requirements as it helps to distinguish different forms of beliefs separately from their impact on policy and other relevant variables. Finally, a probability probe shows that CM-based expectations match Dutch governmental policies quite accurately, attesting to the validity of the method.