Reapproaching Ramsey: Conditionals and Iterated Belief Change in the Spirit of AGM
Reapproaching Ramsey: Conditionals and Iterated Belief Change in the Spirit of AGM
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重新接近拉姆齐：本着年度股东大会精神的条件和反复的信念变化
DOI：
10.1007/s10992-011-9177-3
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发表时间：
2011
影响因子：
1.5
通讯作者：
H. Rott
中科院分区：
文献类型：
--
作者：
H. Rott
根据拉姆齐检验，条件条件反映了信念的变化：α > β在信念状态中被接受，如果β在必要的最小修正中被接受，以适应α。自1986年Gärdenfors的开创性论文以来，一系列不可能定理（“琐碎性定理”）似乎表明，如果将拉姆齐检验与agm类型的信念修正模型结合起来，它就不是一个可行的条件分析。我认为，在坚持年度股东大会精神的同时，支持拉姆齐条件测试是可能的。一个主要的焦点在于AGM的保存条件，根据该条件，原始的信念集在经过与之一致的信息修订后应该被完全保留。我使用信念状态的具体表示和信念状态的（迭代）修订作为（嵌套）条件的语义模型。在迭代信念变化的四个最自然的定性模型中，确定了两个确实允许我们在只包含形式为α > β的平坦条件的语言中将Ramsey检验与保存相结合。然而，对于这种简单语言的保存，对形式为α > (β > γ)的嵌套条件强制违反了保存。在这种语言中，没有两个信念集是由严格的子集包含来排序的。我认为，从一开始就期望保存在包含嵌套条件的语言中成立是错误的。
According to the Ramsey Test, conditionals reflect changes of beliefs: α > β is accepted in a belief state iff β is accepted in the minimal revision of it that is necessary to accommodate α. Since Gärdenfors’s seminal paper of 1986, a series of impossibility theorems (“triviality theorems”) has seemed to show that the Ramsey test is not a viable analysis of conditionals if it is combined with AGM-type belief revision models. I argue that it is possible to endorse that Ramsey test for conditionals while staying true to the spirit of AGM. A main focus lies on AGM’s condition of Preservation according to which the original belief set should be fully retained after a revision by information that is consistent with it. I use concrete representations of belief states and (iterated) revisions of belief states as semantic models for (nested) conditionals. Among the four most natural qualitative models for iterated belief change, two are identified that indeed allow us to combine the Ramsey test with Preservation in the language containing only flat conditionals of the form α > β. It is shown, however, that Preservation for this simple language enforces a violation of Preservation for nested conditionals of the form α > (β > γ). In such languages, no two belief sets are ordered by strict subset inclusion. I argue that it has been wrong right from the start to expect that Preservation holds in languages containing nested conditionals.