In §8 of his Begriffsschrift (1879), Gottlob Frege discusses issues related to identity. Frege begins his most famous essay, “On Sense and Denotation” (1892), published 13 years later, by criticizing the view advocated in §8. He returns to these issues in the concluding paragraph. Controversies continue over these important passages. We offer an interpretation and discuss some alternatives. We defend that in the Begriffsschrift, Frege does not hold that identity is a relation between signs. §8 of the Begriffsschrift is motivated by the conflict between two different criteria for sameness of conceptual content of sentences. To resolve that conflict, Frege introduces ‘≡’ in §8 and, thus, circumstances with names as constituents. To the same end, in “On Sense and Denotation,” Frege introduces senses and Thoughts and abandons both ‘≡’ and circumstances. He solves what we call the Co-instantiation problem , and disregards, but does not solve, the Name problem .

中文翻译：

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令人费解的四个段落：“ ge”和“ =”上的Frege

Gottlob Frege在他的Begriffsschrift（1879）的§8中讨论了与身份相关的问题。弗雷格（Frege）通过批评§8中提倡的观点，开始了他最著名的论文《论意义与外在》（On Sense and Denotation）（1892年），该论文于13年后出版。他在总结段落中再次谈到了这些问题。关于这些重要段落的争论仍在继续。我们提供一种解释并讨论一些替代方法。我们辩称，在Begriffsschrift中，弗雷格不认为同一性是符号之间的关系。Begriffsschrift的第8条是由两个不同的句子概念性内容相同标准之间的冲突引起的。为了解决该冲突，Frege在§8中引入了“≡”，并因此引入了以名称为成分的情况。为了达到同样的目的，在“关于意义和外延”中，弗雷格（Frege）介绍了感官和思想，放弃了“≡”和环境。他解决了我们所谓的“共同实例化”问题，并且无视但没有解决“名称”问题。