Some Problems with “X-Risk: How Humanity Discovered Its Own Extinction”

Dr. Émile P. Torres
8 min readDec 25, 2021


Thomas Moynihan is an intellectual historian currently based at the Future of Humanity Institute. I read his book X-Risk: How Humanity Discovered Its Own Extinction with great interest, but to my disappointment found a very large number of mistakes throughout the manuscript (at least one on almost every page). To illustrate just how ubiquitous these mistakes are, here are a few from the first six pages of the book, which offers a “Timeline” of thinking about human extinction / existential risk.

Moynihan claims that:

→ the bombings of Hiroshima and Nagasaki happened in 1943. They happened in 1945.

→ Rachel Carson’s book Silent Spring “raises the alarm on climate catastrophe.” This is entirely false. The book was about anthropogenic chemical pollutants in the environment, not climate change, which at the time was hardly on anyone’s radar, and indeed a consensus on climate change would not emerge until the 1990s (and especially very early 2000s).

→ “catastrophism [was] vindicated by growing consensus that an impactor killed the dinosaurs” during the 1970s. This is completely wrong. Uniformitarianism (roughly, that global-scale catastrophes never happen, although the view can be analyzed into a cluster of distinct theses) was more or less the only game in town from the 1850s (or so) until the 1980s. More specifically, the Alvarez hypothesis (i.e., the idea that asteroid → dinosaur extinctions) was only first proposed in 1980, and wasn’t fully accepted until about 1991, following the (re)discovery of the Chicxulub crater on the Yucatán Peninsula. There were some reputable scientists who proposed global catastrophes from the 1950s onwards (linking this to supernova, asteroid impacts, etc.), but they were very much in the minority; the overwhelming majority saw catastrophism as fundamentally unscientific until, really, the final decade of the century.

→ in 1930, “J.B.S. Haldane and J.D. Bernal provide first coherent synthesis of ideas regarding long-term potential, existential risk, space colonisation, astroengineering, transhumanism, bioenhancement, and civilisational pitfalls.” Perplexingly, the manuscripts to which Moynihan refers in X-Risk were not published in 1930: Possible Worlds, and Other Essays (Haldane, 1927), The Inequality of Man and Other Essays (Haldane, 1932), The World, the Flesh and the Devil (Bernal, 1929). It is not clear why Moynihan chose this date, nor does this date make any sense.

→ in 1796, “the Marquis de Sade becomes the first proponent of human extinction.” First, I don’t know where the date comes from — Sade didn’t publish any books in 1796! Second, a close read of Sade’s claims shows that he was not, in fact, endorsing human extinction. As I detail in my forthcoming book on the issue, Sade mentioned our extinction for the specific purpose of making several unrelated points, e.g., about the wrongness of the doctrine of hell. (Thus, he writes that if God created people knowing that they would ultimately rot in hell forever, then surely our extinction would be better. This is not to say that our extinction would be desirable; it is a conditional claim, made through the voice of an atheistic fictional character.) Moynihan makes much of this claim — that Sade was the first omnicidal actor — but it is false. Sade wasn’t advocating omnicide!

→ “Nick Bostrom introduces the term ‘existential risk’” in 2003. The correct date is 2002.

→ in 1986, “Eric Drexler published Engines of Creation, hinting at X-risks from nanotech.” Drexler didn’t “hint.” He was explicit that self-replicating nanobots and advanced AI systems could destroy humanity.

→ John Leslie published The End of the World in 1995. The correct publication date is 1996.

→ Hans Jonas “demands a ‘new ethics of responsibility for the distant future’” in 1989. Once again, there’s a numbers problem. The correct date is 1979 (or, better, 1972, as the relevant section of the 1979 book draws from a 1972 conference presentation).

→ in 1965, “I.J. Good speculates that an AI could recursively improve itself and thus trigger a runaway ‘intelligence explosion’, leaving us far behind. It will be our ‘last invention’, he muses.” This is slightly misleading. Although the term “intelligence explosion” was indeed introduced by Good in 1965, the idea goes back at least to a 1959 that Good wrote.

→ in 1943 (Moynihan means 1945), “Faith in inevitable progress takes a battering. Rather than recurrent and omniprevalent owing to its adaptiveness, intelligence comes to be considered as rare and even maladaptive.” But this, too, is misleading: the notion that our intelligence/technological creations/scientific discoveries could pose a dire threat to our collective survival first appears, significantly and explicitly, in the writings of many notable people (like Winston Churchill and Sigmund Freud) after the First World War. The mechanization of violence in WWI triggered a flurry of worries that the next world war could very well be the last conflict in human history — not because the result would be peace, but because it will end in complete extinction.

→ in “reacting to Thomas Malthus, Prince Vladimir Odoevsky publishes first speculation on omnicide (triggered via resource exhaustion and population explosion).” To be clear, though, Odoevsky proposed the scenario as a reductio against Malthus’ theory, that’s it. He meant it to be absurd.

→ in the 1790s, “Deep time and prehistoric extinctions accepted as scientific consensus. Geology unveils a radically nonhuman past.” I’m not sure why Moynihan dates this to the 1790s rather than middle of the eighteenth century. As Stephen Jay Gould writes, “The acceptance of deep time, as a consensus among scholars, spans a period from the mid-seventeenth through the early nineteenth centuries. … ‘Men in Hooke’s times had a past of six thousand years; those of Kant’s times were conscious of a past of millions of years.’”

→ “c.50 BC Lucretius speaks of humankind ‘perishing.’” But I can find no explicit references to this in Lucretius’ On the Nature of Things, nor does the word “perishing” appear in the text that Moynihan cites.

→ “c.75,000 BP Toba supervolcanic eruption rocks the planet. Some evidence implies Homo sapiens nearly goes extinct, but in the wake of the catastrophe, advanced language emerges and knowledge starts accumulating across generations.” This suggests that the catastrophe had something to do with the emergence of language, which is very dubious, and indeed scientists are quite unsure about when language first appeared — perhaps long before, or maybe quite recently. As for knowledge accumulating across generations, members of our genus (and perhaps even of the Australopithecus genus from which Homo emerged) had been passing down, from one generation, knowledge about how to make tools for some 2.6 million years.

Beyond the Timeline:

This is not an exhaustive list of errors in the first few pages of the book. Some of these are relatively insignificant, but others are egregious. The rest of the book, unfortunately, is no less cluttered with avoidable mistakes. For example, consider Moynihan’s claim that “The primary contention of the book is that human extinction is a comparatively novel idea, one that remained entirely unavailable for the greater part of our existence as a species. Homo sapiens has been around for two or three hundred thousand years, yet it is only over the last couple of centuries that members of this species have begun to acknowledge that it might one day cease to exist forever.” But this is not exactly true. Some ancient stories and mythologies really did seem to suggest that humanity could disappear both completely and forever (see, e.g., the epic poem of Atrahasis, in which one of the gods tries repeatedly to eliminate humanity forever). Furthermore, lots of ancient philosophers (poets, sages) imagined what I call “demographic extinction,” whereby humanity disappears entirely, if only temporarily. The ancient atomists, however, espoused a cosmological model that came very close to the idea of humanity disappearing not just entirely but permanently: the universe contains an infinite number of worlds, or kosmoi, that are constantly coming into existence and being destroyed. Once our world is destroyed, it will remain this way forever, although in the vastness of time we might expect another kosmoi arbitrarily similar to ours (with human beings just like us) to form. I go into great detail about this in my forthcoming book. Suffice it to say that our contemporary scientific/naturalistic idea of human extinction has clear roots within the Western tradition in the ancient Greeks, although it was indeed rendered unthinkable between (roughly) the fourth/fifth centuries CE and (most significantly) the nineteenth century, especially the second half.

Moynihan also writes, incorrectly, that “Arthur Schopenhauer was, after Sade, perhaps history’s second omnicidal agent,” adding that Schopenhauer “recommended that humans should abstain from reproducing in order to abolish self-conscious suffering.” This is just plain false: anti-natalism was not part of Schopenhauer’s philosophical system; Schopenhauer never explicitly argued that we should strive to bring about our extinction (although one or two sentences that he wrote, considered out of context, do suggest the opposite). As Robert Wicks, an expert on Schopenhauer, writes: “whether it’s better to have a world filled with ascetics … or a world that has no suffering beings at all, is a toss-up” — a far cry from Moynihan’s declaration that “Schopenhauer was an omnicidal agent.” The confusion continues when Moynihan shifts from Schopenhauer to another German pessimist, Eduard von Hartmann, who Moynihan describes as “Schopenhauer on steroids.” There is no sense in which Hartmann was Schopenhauer on steroids, as Hartmann’s philosophy — which actually was omnicidal — is fundamentally different from Schopenhauers. Although Hartmann did draw from Schopenhauer’s claims about the pervasiveness and fundamentality of suffering in the world, he was far more indebted to Schelling’s metaphysics and Hegel’s theory of history. Hartmann’s philosophy was, essentially, what one gets when one mixes these together and, if anything, he should be seen as writing within a Hegelian tradition.

A trivial error — the sort that one finds on nearly every page — is this: “The German philosopher Immanuel Kant, despite being small of stature and having never left his hometown of Königsberg (modern-day Kaliningrad) …” But it is widely acknowledged that Kant did leave his hometown, although very rarely, and perhaps only once.


I would strongly encourage readers of the book to double-check all of Moynihan’s claims. The book is not reliable. Indeed — and this is true — about 40% of the time that I’ve checked the accuracy of claims, dates, quotes, etc. in X-Risk, I’ve found them to be either misleading or outright false. This could have been an excellent book, but as it stands I would not recommend it to anyone.

(Far more serious problems with parts of the book have also been brought to my attention, but I do not have permission to discuss them yet.)

Feel free to email me at if you find additional mistakes.

(Thanks to Dan Zimmer for catching some of these mistakes that slipped my eye.)



Dr. Émile P. Torres

I study all things human extinction: its nature and causes, its ethical implications, & the history of the idea. Philosopher, but MS in Neuroscience.