History, Kindness, and the Great Evolutionary Faunas — Extinct

Finally, consider history. Are evolutionary faunas kinds whose members share “the selfsame [token or type] history” (p. 3)?  I’m not sure how to answer this. By most accounts, history consists of an unrepeatable sequence of unique events, which suggests that “sharing a selfsame history” means participating in or being affected by the same set of unrepeatable or unique events. Presumably there are no discrete events that all members of an evolutionary fauna participate in or are affected by. This means (if I have understood the concept of “shared history” correctly) that members of a fauna cannot be said to share a token history. Yet recall Sepkoski’s claim that each evolutionary fauna is “intimately associated with a particular phase in the history of total marine diversity” (Sepkoski 1981, 36). This could be taken to mean that it is a taxon’s “association with a particular phase in the history of marine diversity” that sorts it into a fauna. The proposal is not altogether straightforward. As you can see in the figure (above), faunas overlap one another in time, so the mapping of faunas onto periods of history is not one-to-one. Still, as the names of the faunas indicate, there is something important about the temporal location of a fauna, such that what it is to be a particular fauna (and also, I take it, a member of that fauna) is partly a matter of being situated at a particular juncture in the history of marine diversity.

I am not sure whether this means that members of a fauna share a type history. But it strikes me that this is the most promising niche in Khalidi’s account for the great evolutionary faunas, assuming I have interpreted the categories correctly.

* * *

As I said before, these comments are not offered in the spirit of a counterexample. Instead, they are intended to show where the framework bulges when it is asked to digest a substantial and difficult scientific meal. Khalidi says that historical kinds are kinds whose members “share a (token or type) origin, history, or causal trajectory.” But in the present case, it doesn’t seem like the members of an evolutionary fauna share a token or type origin or causal trajectory, and it is questionable whether they can be said to share a “history.” By contrast, evolutionary faunas themselves share all or none of these depending on how the criteria are interpreted and the empirical phenomena characterized. Clarifying the criterion of shared history would obviously help in resolving these difficulties. But if I were to make a suggestion, it would be to consider a category of historical kinds whose members share a temporal location, or even a position in a temporal succession, as opposed to a “history” per se. This would go some way towards illuminating why members of an evolutionary fauna constitute a meaningful association, even though they do not share a (token) origin or causal trajectory.

I have so far ignored Khalidi’s distinction between “pure” and “impure” kinds: between kinds delineated solely with respect to historical properties and those only partly delimited on the basis of historical properties. But here it bears mentioning that evolutionary faunas are “impure kinds,” since they are delineated not only on the basis of their temporal position with respect to other faunas, but also in virtue of their members’ shared ecologies (Alroy 2004). This distributes the burden of accounting for kind-membership over a set of properties that includes both historical and non-historical ones. And this, I think, makes it more plausible to claim that fauna members share only a fairly thin historical property like temporal location. The historical property can be thin because it is not doing all the work of delineating the relevant kind. Shared ecology is at least as important.

I end with a word of advocacy. According to Khalidi’s general account of natural kinds, members of a kind are entities that occupy a shared node in the causal structure of the world (Khalidi 2018). This means that natural kinds “divide the world into individuals that share causal properties, enter into the same or similar causal relationships, and give rise to the same or similar causal processes.” In all this, explanatory considerations are paramount—Khalidi exhibits a pronounced hesitancy to embrace “truthful description” as an important goal of scientific inquiry, on a par with prediction and explanation. But in the historical sciences, truthful description is a weighty accomplishment indeed, and supplies the goal of many research projects (Dresow 2021; Dresow and Love 2022). This includes Sepkoski’s description of the great evolutionary faunas, whose primary aim is to reduce the chaos of the fossil record to something resembling order and simplicity.

We should not shrink from the implication, nor should we doubt the capacity of sophisticated descriptive practices to uncover the contours of natural groupings. While I am inclined to agree with Khalidi that prediction and explanation provide our best guides to nature’s divisions, sophisticated practices of characterization provide reliable guides as well.


Alroy, J. 2004. Are Sepkoski’s evolutionary faunas dynamically coherent? Evolutionary Ecology Research 6:1–32.

Bokulich, A. 2020. Understanding scientific types: holotypes, stratotypes, and measurement prototypes. Biology & Philosophy 35:1–28.

Currie, A.C. 2019. Scientific Knowledge and the Deep Past. Cambridge: Cambridge University Press.

Dresow, M. 2021. Explaining the apocalypse: the end-Permian mass extinction and the dynamics of explanation in geohistory.” Synthese. https://doi.org/10.1007/s11229-021-03254-w. [Despite the mention of “explanation” in the title, this paper is largely about the importance of descriptive or “characterizational” research in geohistory.]

Dresow, M., and Love, A.C. 2022. The interdisciplinary entanglement of characterization and explanation. The British Journal for the Philosophy of Science. https://doi.org/10.1086/720414. [This paper offers a refined account of scientific characterization for complex phenomena, focusing on the Cambrian Explosion.]

Franklin-Hall, L. 2020. The animal sexes as historical explanatory kinds. In S. Dasgupta, R. Dotan, B. Weslake (Eds.), Current Controversies in Philosophy of Science, 177–197. New York: Routledge.

Khalidi, M. 2018. Natural kinds as nodes in causal networks. Synthese 195:1379–1396.

Khalidi, M. 2022. Etiological kinds. Philosophy of Science 88:1–21.

Sepkoski, J.J., Jr. 1981. A factor analytic description of the Phanerozoic marine fossil record. Paleobiology 7:36–54.

Simpson, G.G. 1964. This View of Life: The World of an Evolutionist. New York: Harcourt, Brace, & World.

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