In this paper, we investigate the semantics and logic of choice-driven counterfactuals, that is, of counterfactuals whose evaluation relies on auxiliary premises about how agents are expected to act, i.e., about their default choice behavior. To do this, we merge one of the most prominent logics of agency in the philosophical literature, namely stit logic (Belnap et al. 2001; Horty 2001), with the well-known logic of counterfactuals due to Stalnaker (1968) and Lewis (1973). A key component of our semantics for counterfactuals is to distinguish between deviant and non-deviant actions at a moment, where an action available to an agent at a moment is deviant when its performance does not agree with the agent’s default choice behavior at that moment. After developing and axiomatizing a stit logic with action types, instants, and deviant actions, we study the philosophical implications and logical properties of two candidate semantics for choice-driven counterfactuals, one called rewind models inspired by Lewis (Nous 13(4), 455–476 1979) and the other called independence models motivated by well-known counterexamples to Lewis’s proposal Slote (Philos. Rev. 87(1), 3–27 1978). In the last part of the paper we consider how to evaluate choice-driven counterfactuals at moments arrived at by some agents performing a deviant action.

在本文中，我们研究了选择驱动的反事实的语义和逻辑，也就是说，反事实的评估依赖于关于代理如何行动的辅助前提，即关于他们的默认选择行为。为此，我们将哲学文献中最突出的能动性逻辑之一，即 stit 逻辑（Belnap 等人，2001 年；Horty 2001 年）与 Stalnaker（1968 年）和 Lewis（ 1973）。我们反事实语义的一个关键组成部分是区分异常和非异常某一时刻的动作，当某个时刻可用于代理的动作的表现与当时代理的默认选择行为不一致时，该动作是不正常的。在开发和公理化具有动作类型、瞬间和异常动作的 stit 逻辑之后，我们研究了选择驱动的反事实的两种候选语义的哲学含义和逻辑属性，一种称为受刘易斯启发的倒带模型( Nous 13 (4), 455 –476 1979) 和其他被称为独立模型的动机是由著名的刘易斯提案 Slote 的反例激发的 ( Philos. Rev. 87(1), 3-27 1978)。在论文的最后一部分，我们考虑了如何评估某些代理执行异常行为时出现的选择驱动的反事实。