Estimating whether the Earth’s biota is in the middle of a crisis relies heavily on comparisons between present and past data about biodiversity or biodiversity surrogates. Although the past is a crucial source of information to assess the severity of the current biodiversity crisis, substantive conceptual and methodological questions remain about how paleodiversity and biodiversity are to be properly compared. I argue that to justify claims of a current biodiversity crisis is harder than it appears. More precisely, I claim that paleodiversity measurements are incommensurable with contemporary measurements, given the different ways that biodiversity is conceptualized and operationalized. I conclude by proposing three possible ways of overcoming this incommensurability problem.

估计地球生物群是否处于危机之中，很大程度上依赖于对当前和过去有关生物多样性或生物多样性替代数据的数据进行比较。尽管过去是评估当前生物多样性危机严重性的重要信息来源，但关于如何适当比较古生物多样性和生物多样性的实质性概念和方法问题仍然存在。我认为，要证明当前生物多样性危机的说法比看起来更难。更准确地说，鉴于生物多样性被概念化和操作的不同方式，我声称古生物多样性测量与当代测量是无法比较的。最后，我提出了三种可能的方法来克服这个不可通约性问题。