Proposal of Economic Historical Studies: Rationality of Extra-Institutional Mediators and Interdisciplinary Re-evaluation

This paper proposes a new academic field, "Economic Historical Studies," which integrates economic theory, behavioral economics, and institutional design into historiography. Conventional history often relies on hero narratives and anecdotal accounts, overlooking institutional conditions and rational choices. By reinterpreting the case of Sakamoto Ryōma as a rational mediator who moved institutions from outside, this study highlights the limitations of traditional historiography and the stagnation of interdisciplinarity. It argues for a systematic framework to analyze extra-institutional actors and to reconstruct history into a knowledge system applicable to future institutional design and policy. Future developments of this field may include comparative analyses of historical mediators across cultures, quantitative modeling of cooperation and conflict using game theory, and the integration of behavioral biases into historical decision-making frameworks. Such approaches would not only enrich historiography but also provide actionable insights for contemporary policy design, organizational reform, and interdisciplinary education. By establishing reproducible criteria for institutional change, Economic Historical Studies aims to transform history from a narrative of past events into a diagnostic and generative tool for shaping future societies. An additional contribution of this field is the incorporation of personality-based rationality into historical analysis. By examining behavioral biases such as present bias and loss aversion, Economic Historical Studies can distinguish between impulsive, short-term risk-taking actions and future-oriented rational choices. The case of Sakamoto Ryōma demonstrates how a low present bias enabled him to avoid gambling-like impulses, reject assassination as a short-term solution, and instead pursue negotiation, organizational design, and indirect proposals. This perspective not only clarifies why certain mediators succeeded where others failed, but also provides a framework for evaluating the psychological conditions under which institutional change becomes possible. In contrast, the assassinations of Prime Minister Inukai Tsuyoshi in 1932 and Prime Minister Takahashi Korekiyo in 1936 illustrate the destructive consequences of high present bias. In both cases, perpetrators prioritized immediate emotional or political satisfaction over long-term institutional stability, rejecting persuasion and rational policy. Had present bias been lower, these actors might have accepted negotiation and altered the trajectory of Japanese history. By juxtaposing Ryōma’s rational mediation with these impulsive assassinations, Economic Historical Studies highlights how behavioral economics can illuminate the psychological boundaries between institutional reform and institutional collapse.