Optimism and pessimism in strategic interactions under ignorance
研究玩家在无知下互动时，基于粗糙信念采用最大最小或最大最大决策准则，分别对应悲观或乐观态度，并刻画了共同信念下的行为含义，发现乐观与点理性化相关，悲观由新算法Wald理性化捕捉。
We study players interacting under the veil of ignorance, who have—coarse—beliefs represented as subsets of opponents’ actions. We analyze when these players follow max min or max max decision criteria, which we identify with pessimistic or optimistic attitudes, respectively. Explicitly formalizing these attitudes and how players reason interactively under ignorance, we characterize the behavioral implications related to common belief in these events: while optimism is related to Point Rationalizability, a new algorithm—Wald Rationalizability— captures pessimism. Our characterizations allow us to uncover novel results: (i) regarding optimism, we relate it to wishful thinking á la Yildiz (2007) and we prove that dropping the (implicit) “belief-implies-truth” assumption reverses an existence failure described therein; (ii) we shed light on the notion of rationality in ordinal games; (iii) we clarify the conceptual underpinnings behind a discontinuity in Rationalizability hinted in the analysis of Weinstein (2016).