因果决策理论视野下的纽科姆难题

Newcomb's Problem from the Perspective of Causal Decision Theory

传统决策理论回避因果关系,纽科姆难题的提出构成了对它的严重质疑。同时,关于纽科姆难题的讨论推动了因果决策理论的进步。如吉伯德和哈珀基于因果关系的反事实理论为主观因果决策理论辩护;斯科姆斯不使用反事实理论,而在概率论基础上建构因果关系理论,并为主观因果决策理论辩护;索贝尔的决策理论是基于因果关系的概率性反事实理论;刘易斯则基于模态逻辑提出了因果反事实的观点。这些理论的共同特点是使用因果关系来解决不确定性情况下的决策问题。然而基于决策逻辑的这种共同基因,导致它们仍然存在各自的局限性。对这些问题的讨论,有助于推进决策问题研究中关于概率、效用以及分区问题的思考。

Traditional decision theory avoids causation,but the Newcomb's problem constitutes a counter example to traditional decision theory,and the discussion of the Newcomb's problem has contributed to the advancement of causal decision theory.For example,Gibbard and Harper defended the subjective causal decision theory,which is a counter factual theory based on causality.Skyrm's theory of causality based on probabilistic theories defended the subjective causal decision theory.Sobel's theory is a probabilistic counter factual theory based on causality,and Lewis put forward a causal counter factual view based on modal logic.The common feature of these theories is the use of causality to solve decision problems under uncertainty.However,this common genesis based on decision logic leads to the fact that they still have their own limitations.The discussion of these issues will further provoke thinking about probability and utility issues in decision problems and about partitioning.