Enlightenment and the Discovery of Human Extinction

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by guest contributor Dr. Thomas Moynihan

The idea of human extinction first appeared in the eighteenth century. A perennial tradition of religious eschatology and apocalypse has, of course, existed throughout history. But human extinction represents a novel and distinct idea. Simply put, where apocalypse secures a sense of an ending, extinction prognoses the ending of sense. Human extinction is predicated upon an awareness of our precarity as a biological species within a desacralized universe, and, as such, was not so much as even thinkable prior to a certain point. Most immediately, it became so much as thinkable—and, eventually, a target of our anticipatory concern and mitigative strategizing—due to the consolidation, across the seventeenth to nineteenth centuries, of several new domains of empirical science. These were the geosciences, population science, and actuarial probabilism. The first gave us awareness of nature’s contingence and historicity; the second gave us sensitivity to our position as a biophysical species; the third inculcated a rigorized understanding of risk and uncertainty. This post will home in on the first of these: the earth sciences.

Assiduous description of empirical fact in and of itself was not sufficient to make available the concept of human extinction. Prior to a certain point in time, people simply believed that, should we die out today, the human species (or something either identical or axiologically equitable) would inevitably and eventually re-emerge. This was based upon the age-old presumption that it is the nature of the cosmos to be as maximally full of moral worth as is possible. Arthur Lovejoy, of course, once baptized one persistent form of this conviction as ‘the Principle of Plenitude’ in his 1936 The Great Chain of Being. Ergo, coming to care about our extinction involved not only empirical investigations but, also, in-step reflections upon the positionality and propriety of sapience and its value as such. Simply put, we had to disentangle ‘fact’ from ‘value’ before we could become gripped by the prospective fact of the end of all value. The cosmos had to be desacralized before extinction could become axiologically meaningful. This realization came from that master idea of Enlightenment philosophy, reaching its culmination in Kantian critique: the acknowledgement that norms are things that we elect to bind ourselves by and are thus not at all features of the natural world independently of this ongoing election. Apprehending this led us to acknowledge that we alone are responsible for the thing we call ‘mind’; which, in turn, is how we first came to be gripped by the prospect of its extinction and first became motivated to forecast our future.

One perfect case study of how theoretical assumption of ‘plenitude’ prevented appreciation of the true stakes involved in extinction—even after acceptance of the empirical fact of species extinctions—comes from eighteenth-century and nineteenth-century geology.

Put most simply, ‘plenitude’ entails that all legitimate possibilities are eventually realized: this essentially meant that, should any species die out, the possibility of its returning will at some point be fulfilled. In turn, this basically obstructed conceptualization of species extinctions (whether human or non-human) from Antiquity to the Enlightenment. The severity of such an event—its terminal nature—was simply not conceptually available. (Indeed, myriad fossil evidences were recorded by the Ancient Greeks, but the suggestion that they are facsimiles of irreversibly deceased fauna remained elusive until the late seventeenth century.) Extinction was utterly trivialized by the cosmic cycles of death and rebirth that plenitude enforces.

One can see this at work in the first recognizably geohistorical conjectures. These came from Robert Hooke and Edmond Halley across a period spanning from the 1660s to the 1710s. Both polymaths, that is, were the first to inject naturally caused vicissitude into their models of earth systems. The former proposed a terrestrial history riven by gigantic earthquakes, wherein the planet’s ever-changing surface led to “divers Species of Creatures” becoming “quite lost” (‘Lectures and Discourses on Earthquakes’, 435). (This was the first ever unequivocal endorsement of the idea of species extinctions.) Not long after Hooke’s conjectures, Halley ventured modernity’s first ever image of something looking like what we now call mass extinction event. He speculated the “causal shock of a comet” could cause such a cataclysm that “all things [living] should hereby be destroyed” (‘Considerations about the Cause of the Universal Deluge’, 122).

Nonetheless, despite admitting such calamity into their theories of nature, they could not accommodate ‘existential catastrophes’ or ‘human extinction events’. Halley, that is, maintained that such wipe-outs had happened multiple times prior to the current “Creation”. Each time, however, this was merely a localized truncation within an unending cycle of returning civilizations. A ‘punctuated eternalism’, if you will. Hooke even imagined that, prior to the previous world-order’s devastation, there had been a “preceding learned Age”: of perhaps even greater knowledge than the present (‘Lectures and Discourses on Earthquakes’, 328). (Projecting the ‘anxiety of influence’ between Ancients and Moderns onto geohistory, Hooke tantalized himself with the irrecuperable learnings of these prior peoples.)  In short, both savants presumed that an ‘annihilated’ humanity would persistently reappear and repopulate the desolate earth after each global desecration.

By 1750, the French polymath surgeon Claude-Nicholas Le Cat repackaged this now-familiar cycle of “ruin and renovation” in his own ‘Theory of the Earth’. However, Le Cat was conspicuously unclear as to whether humans would, indeed, inevitably return after the next world-collapse. A shocked reviewer of Le Cat’s book on the topic picked up on this equivocation, demanding to know whether “earth shall be re-peopled with new inhabitants” after any future desecration (‘An Account of Several Systems, Particularly that of the Ingenious Mr. Le Cat’, 384). In reply, Le Cat dodged the reviewer’s accusation of departing from orthodoxy (comparing himself to Galileo and Copernicus in the process) but not without wryly musing—with graveside smile—that there

are already a sufficient number of animals and men buried in the earth to gratify the curiosity of the new inhabitants of the new world, if there be any.

Ibid, 388

Surely this did not appease the perturbed reviewer. Nonetheless, Le Cat’s facetiousness aside, the ruin-and-renovation cycle remained a well-worn method for trivializing the stakes involved in existential precarity.

Indeed, decades later, the geologist Charles Lyell would perpetuate these naïve ideas of unending cycles (even after evidence of prehistoric extinctions had become undeniable). Confidently championing “invariable constancy in the order of nature”, the same presumptions that led Hooke and Halley to postulate eternally returning civilizations led Lyell to opine that the “the iguanodon might reappear in the woods” (Principles of Geology, i.123). He spoke to one of his colleagues of de-extincted dinosaurs repopulating Sussex in the deep future. He was confident: we must consider all extinctions within natural history as “merely local”; for, given the correct “conditions”, those “genera of animals” which are currently “preserved [in] ancient rocks” will inexorably “return”. And, by obvious entailment, if this applies to pterodactyls and ichthyosauri then why would it not also apply to humans? As the theologian Edward Nares jubilated in a treatise on geology and scripture a few years after Lyell’s publication: “Here then is no extinction for us” (Man, as Known to us Theologically and Geologically, 240).

Quite simply, plenitude, by collapsing the space of possibility entirely into eventual actualizations allows no ultimate distinction between talk of ‘what ought to happen’ and ‘what will happen’. It prohibits any ultimate differentiation between ‘fact’ and ‘value’. Mingling norm and nature, normativity can never truly go extinct. Insofar as one presumes plenitude, one simply cannot grasp the true stakes involved in extinction. Human minds, after all, will simply return.

Nonetheless, by the opening of the nineteenth century, the separation between the world of value and that of facts was becoming stark. This can be seen in Lyell’s own writing, where he pondered whether the first appearance of human civilization would constitute a breach of his “invariable constancy” in nature’s cycles. Imagining an extraterrestrial observer looking on our planet from afar, he realized that the reorganizing effect wrought by human intentionality upon our biosphere and lithosphere would be unmistakable. (The notion of the ‘Anthropocene’ is not so new, it would seem.) Would this constitute a breach of the “regularity of the system”, Lyell asked? No, since the “new and extraordinary circumstances” of rationality’s emergence are, he claimed, innovations not of a “physical, but [of] a moral nature” (Principles of Geology, i.163-4). Lyell was here falling back upon a specious dualism of ‘natural’ and ‘supernatural’, yet such a position was becoming untenable. Values may not be identical with widest nature—but neither are they at all supernatural—as they emerge from the discursive activities of value-mongering creatures. Thus, there is simply no guarantee that they will inevitably return should we disappear.

By the late 1850s, Lyell could no longer deny such portents. Considering the “millions of years” of “extinction”, Lyell admitted in his private notebooks that this law must be “the same for Man & Animals.” By now a close friend of Darwin, Lyell wrote that if evolution “be true we must look [at] the whole prospect in the face”. Though he remained confident that “more intellectual beings” would supersede us, he nonetheless admitted that this is a “future paradox from which our race shall be excluded” (Lyell’s Scientific Journals on the Species Question, 180-200). In other words, Lyell now realized the stakes involved in our extinction: human-like intellect isn’t part of the furniture of the natural world such that, should we fail to protect it, it will not inevitably and ineluctably return or persist. Indeed, as a contemporary astrobiologist, Charles H. Lineweaver, has recently written, “human-like intelligence seems to be what its name implies—species specific.” Cosmic nonchalance regarding its return is, then as now, not warranted.

Thomas Moynihan recently completed his Ph.D. at Oriel College, Oxford. It focused on the intellectual history of ideas of human extinction and existential risk. His ongoing research is concerned with the long-term historical genesis of our concern for the deep future and our placement within it.

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