理性的第一条件是避免毁灭

一项策略可以有很高的平均收益，只要其中一次损失足以让人破产，那个平均值对个人就没有多少用。群体里的一百个人各承担一次风险，和同一个人连续承担一百次风险，使用的概率看起来一样，结果却可能完全不同。后者一旦归零，后面的机会也就没有了。

所谓长期收益隐藏着一个前提，参与者能够活到那个长期。不对称比预测重要 因此把问题从发生概率换成暴露结构，杠铃策略 再把大部分资源放到不会出局的一端。两张卡都从这里往下展开。

生存也不能单独证明一项制度合理。坏制度可能靠暴力、资源和路径依赖延续很久。这里讨论的只是行动条件：没有继续参与的资格，后面的计算便失去了对象。

《Skin in the Game》原文：

a) rationality resides in what you do, not in what you think or in what you “believe” (skin in the game), and b) rationality is about survival.

as per the expression attributed to Hobbes: Primum vivere, deinde philosophari (First, live; then philosophize).

Hence the more “systemic” things are, the more important survival becomes.

Simon formulated the notion now known as bounded rationality: we cannot possibly measure and assess everything as if we were a computer; we therefore produce, under evolutionary pressures, some shortcuts and distortions. Our knowledge of the world is fundamentally incomplete, so we need to avoid getting into unanticipated trouble. And even if our knowledge of the world were complete, it would still be computationally near-impossible to produce a precise, unbiased understanding of reality. A fertile research program on ecological rationality came out of the effort to cure Simon’s problem; it is mostly organized and led by Gerd Gigerenzer (the one who critiqued Dawkins in Chapter 9), mapping how many things we do that appear, on the surface, illogical, but have deeper reasons.

Rationality does not depend on explicit verbalistic explanatory factors; it is only what aids survival, what avoids ruin.

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