When Is a Strategy in Games?

Strategic reasoning is everywhere. Given the dominance of game theory, there are many serious problems with the concept of strategy. Not to mention the classical game theory, which aimed at the highest mathematical abstraction, it is rare to find serious attempts to capture the essence of strategic reasoning even in more recent trends in game theory, such as evolutionary or epistemic game theory. Good news is that logicians and game theorists are becoming more enthusiastic about their collaborations. I shall argue, however, there is an unbridgeable gap between the concept of strategy in game theory and that in real games. As an antidote, I propose to analyze the concept of strategy in Baduk (Weiqi, Go). For, in this ancient Asian board game, which has become famous by the recent success of AlphaGo, we can get lessons for both theoretical and practical reasoning. Ultimately, I aim at a concept of strategy, according to which (1) it is not necessarily the case that a strategy is found in any game, (2) there has to be an intriguing interaction between a strategy and tactics, and (3) it is inconsistency-robust. I shall present an analysis of a historical game record as an example that satisfies all these desiderata.