In order to block controversial predictions of 2D semantics (The Nesting Problem), Chalmers and Rabern (2014) propose adding an additional constriction called “the liveness constraint” in definitions of epistemic modals. Without this constraint, all scenario‐world pairs counterfactual to a scenario‐world pair considered as actual in a 2D matrix for a contingent a priori proposition ϕ appear problematic for 2D semantics. This is because, although it is false that ϕ in such pairs, it is a priori true that ϕ. I consider two versions of 2D semantics, those with unstructured and structured intensions. I argue that the unstructured version of 2D semantics is over‐simplified and due to this, it has controversial predictions for counterfactual scenario‐world pairs – the definition of epistemic conceivability with the liveness constraint causes some contingent propositions to appear inconceivable in counterfactual scenario‐world pairs, while some other contingent propositions remain conceivable. In turn, the structured version of the 2D account of propositions has no explanation of how it is possible to possess purely qualitative knowledge without its being dependent on a particular individual or on a particular actual world.

中文翻译：

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变异性，刚性和嵌套问题

为了阻止对2D语义的有争议的预测（嵌套问题），Chalmers和Rabern（2014）建议在认知模态的定义中添加一个称为“活力约束”的附加约束。如果没有这个限制，所有场景的世界对反事实的情况下，世界对以2D矩阵的队伍视为实际先验命题φ出现问题的二维语义。这是因为，虽然它是假的是φ在这样的对，这是一个先验的事实，φ。我考虑了2D语义的两个版本，它们具有非结构化和结构化的内涵。我认为2D语义的非结构化版本过于简化了，因此，它对反事实情景世界有预测性的争议–带有活动性约束的认知可思议性的定义会导致一些偶然的命题在反事实情景世界中显得难以想象对，而其他一些或有命题仍然可以想象。反过来，命题的2D帐户的结构化版本没有解释如何在不依赖特定个人或特定实际世界的情况下拥有纯粹的定性知识。