The main theme of the conference was "Interdisciplinarity of Economic Policy Studies." This special issue is mostly based on the papers presented at the keynote speech and plenary session of the conference.The problems in the world are becoming more serious and complicated. In such a situation, policymaking based on relevant evidence is required and it is important to obtain the evidence based on not only one academic field but also various disciplines. In this special issue, work ethics, recursive expectations approach, and environmental problems are considered. The topics have important recommendations for the future.The first paper is titled "Grounding Multidisciplinary Public Policy Analysis in Methodological Individualism: With an Illustrating Study of the Economic and Political Effects of Variations in a Nation's Average Work Ethic" and written by Professor Roger Congleton. The author discusses how rational choice analysis can be expanded to interdisciplinary analyses. He presents a "homo constitutionalus" model which can provide foundations for rational choice models that account for how internalized rules systematically affect the choices of individuals. Using the model, this paper explains the economic and political effects of the average strength of nation's work ethic [1].The second paper is titled "Recursive expectations approach in policymaking" and written by Professor Keiichiro Kobayashi. The author insists that policymakers need recursive thinking, that is, the ability to think about thinking. This paper reviews three cases resulted from the lack of recursive thinking: delayed disposals of nonperforming loans in the 1990s, secular stagnation and unconventional monetary policy in the 2000-2010s, and restrictive PCR testing during the pandemic. The