Tatsuo Tanaka - Retiring in AY2022

As many retiring faculty members say, the past 24 years have flown by. During this time, I have met wonderful, open-minded colleagues and been surrounded by brilliant and motivated students, and I have had a happy time. I have nothing but words of gratitude for Keio University.

As an undergraduate, I was not in the Faculty of Economics but in the College of Arts and Sciences. Because of this, I studied a wide range of subjects during my undergraduate years, including not only economics but also political science and sociology. My mentor at the time, Professor Yasusuke Murakami, had a background in economics, which led me to pursue graduate studies in economics. However, I feel that the perspectives from this wide range of academic fields have continued to live within me. To put it simply, it is a sense of skepticism toward the rationality that economics assumes.

Economics fundamentally assumes rationality. Although discussions that relax the assumption of rationality, such as in behavioral economics, have emerged recently, it was commonplace at the time for economics to assume rational individuals. Rationality means maximizing some objective function, and some even asserted that economic problems are constrained maximization problems. The thing to be maximized is an individual's utility (or profit in the case of a firm), and the economic model involves choosing the quantity of goods to maximize utility, given income and prices.

However, can human behavior be explained by such rational optimization behavior? As someone familiar with other fields like political science and sociology, I cannot shake my skepticism. For example, a business guide at the time stated that marriage is an investment. Indeed, marriage has aspects of an investment. One spends a long period with a partner, investing time and money. The benefits obtained can be children or rest at home, and there is also the risk of failure, which is divorce. If there are inputs and benefits, and even a risk of failure, it is logical to consider it an investment. If it is an investment, then one should make the most rational choice—that is, rationally choose a partner.

But is that what marriage is really about? It seems that in reality, people take the plunge driven by passion, on impulse, or due to unavoidable circumstances, which can hardly be called a rational choice. And this is not necessarily a bad thing. Rather, it seems to me that people who choose a partner based on rational thinking live a dull life. At least, it's not very interesting. Not limited to marriage, I don't think that people who act rationally necessarily live a good life.

This sense of incongruity manifested in various ways and steered my research away from the mainstream of economics. For example, there is a field called evolutionary economics. Individual organisms do not necessarily act based on rational calculations but follow pre-programmed instincts. Nevertheless, in the long run, they adapt splendidly to their environment and, as a result, appear to act rationally. Evolutionary economics seeks to incorporate this concept of evolution into economics. I translated a book by Nelson and Winter, pioneers in this field, and also created evolutionary models myself.

Similarly, my unease with rational behavior was one reason I began researching the entertainment industry, including games, music, movies, and anime. Unlike other consumer goods, the entertainment industry is not essential for daily life. What is pursued there is how much time and effort to devote to one's favorite content (what is known as 'oshi'), and this is somewhat unbalanced to be explained by economic rationality. The creators who provide the content are not always focused solely on making a profit; many also value interaction with their fans. Both sides want to have a good time with their favorite content or with the fans, and the goal itself is to spend fulfilling time, rather than engaging in optimization behavior.

My recent focus on studying the nature of online communication follows this same trajectory. It is often said that the consumption of goods is sluggish, such as young people's move away from cars. So, what do they do in their spare time? They are constantly looking at their smartphones. While some of this involves entertainment, most of it is communication. Interacting with many people and having a good time has become their goal. Therefore, it seemed appropriate to take this up as a subject of analysis. I set my research question as how to maintain a good communication environment and began analyzing factors that hinder communication, such as online flame wars, polarization, and fake news.

These interests are likely considered unorthodox from the perspective of economics as a whole. However, I believe Keio University was broad-minded enough to accept such unorthodoxy. I am sincerely grateful to the university for allowing me to pursue the research I loved to my heart's content, without worrying about what others thought.

And the students, too, were kind enough to go along with someone like me. It seems my seminar was known among students at the Faculty of Economics, Keio University, as the one where 'otaku' gathered. I am rather proud of this. I am still connected with my students through alumni association meetings, and I intend to maintain these connections in the future. It is the greatest reward for a teacher to see how the students who grew up in my seminar will make their way in the world.

Being blessed with good colleagues and wonderful students, and being able to immerse myself in the research I love—when I think about it, this is an extremely fortunate thing. I want to express my heartfelt gratitude to Keio University for providing me with such an environment. Thank you.