A PROBABILISTIC SEMANTICS FOR COUNTERFACTUALS. PART A
A PROBABILISTIC SEMANTICS FOR COUNTERFACTUALS. PART A
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反事实的概率语义。
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
H. Leitgeb
中科院分区：
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作者：
H. Leitgeb
这是论文的A部分我们为反事实的语义辩护它是概率性的因为反事实的真值条件指的是概率测度。由于它的概率性质，它允许反事实的“如果a则B”为真，即使存在相关的“a而不是B”世界，只要这种例外情况不太广泛传播。通过表示定理使语义在不同的版本中变得精确和研究。尽管其概率性质，我们表明语义和由此产生的逻辑系统可以被视为David Lewis的真值-条件语义和反事实逻辑的自然证明变体。同时，语义在很多方面与Ernest Adams的非真条件假设理论重叠。我们认为，反事实具有两种语用意义，并附带两种可接受度或可信度，一种是假设的，另一种是由我们的概率语义决定的基于真理的；由于反事实的新的琐碎性结果，这些程度不可能总是一致的，它们不应根据其不同的解释和实用目的来确定。然而，对于简单的可断言性来说，它们之间的区别并不重要。因此，如果反事实的假设理论被足够小心地表述，那么我们的反事实的真条件理论与它是一致的。我们的调查结果被用来评估霍桑和Hájek认为的一个主张，即大多数普通反事实是错误的论点。
This is part A of a paper in which we defend a semantics for counterfactuals which is probabilistic in the sense that the truth condition for counterfactuals refers to a probability measure. Because of its probabilistic nature, it allows a counterfactual ‘if A then B’ to be true even in the presence of relevant ‘A and not B’-worlds, as long such exceptions are not too widely spread. The semantics is made precise and studied in different versions which are related to each other by representation theorems. Despite its probabilistic nature, we show that the semantics and the resulting system of logic may be regarded as a naturalistically vindicated variant of David Lewis’ truth-conditional semantics and logic of counterfactuals. At the same time, the semantics overlaps in various ways with the non-truth-conditional suppositional theory for conditionals that derives from Ernest Adams’ work. We argue that counterfactuals have two kinds of pragmatic meanings and come attached with two types of degrees of acceptability or belief, one being suppositional, the other one being truth based as determined by our probabilistic semantics; these degrees could not always coincide due to a new triviality result for counterfactuals, and they should not be identified in the light of their different interpretation and pragmatic purpose. However, for plain assertability the difference between them does not matter. Hence, if the suppositional theory of counterfactuals is formulated with sufficient care, our truth-conditional theory of counterfactuals is consistent with it. The results of our investigation are used to assess a claim considered by Hawthorne and Hájek, that is, the thesis that most ordinary counterfactuals are false.