History disproves extinction risk – even tiny chances are exaggerated

Most events pose existential risks of this magnitude or lower, so if Ord wants us to accept that natural pandemics have a 1/10,000 chance of leading to irreversible existential catastrophe by 2100, Ord owes us a solid argument for this conclusion. It is certainly far from obvious: for example, devastating as the COVID-19 pandemic was, I don’t think anyone believes that 10,000 random re-rolls of the COVID-19 pandemic would lead to at least one existential catastrophe. The COVID-19 pandemic just was not the sort of thing to pose a meaningful threat of existential catastrophe, so if natural pandemics are meant to go beyond the threat posed by the recent COVID-19 pandemic, Ord really should tell us how they do so.

Ord begins by surveying four historical pandemics: the Plague of Justinian, Black Death, Columbian Exchange, and Spanish Flu. Ord notes that while each of these events led to substantial loss of life, most were met with surprising resilience.

Even events like these fall short of being a threat to humanity’s longterm potential. In the great bubonic plagues we saw civilization in the affected areas falter, but recover. The regional 25 to 50 percent death rate was not enough to precipitate a continent-wide collapse of civilization. It changed the relative fortunes of empires, and may have altered the course of history substantially, but if anything, it gives us reason to believe that human civilization is likely to make it through future events with similar death rates, even if they were global in scale.

I drew a similar lesson from the study of historical pandemics in Part 9 of this series.

Next, Ord notes that the fossil record suggests the historical risk of existential catastrophe from naturally occurring pandemics was low:

The strongest case against existential risk from natural pandemics is the fossil record argument from Chapter 3. Extinction risk from natural causes above 0.1 percent per century is incompatible with the evidence of how long humanity and similar species have lasted.

This accords with what we found in Part 9 of this series: the fossil record reveals only a single confirmed mammalian extinction due to disease, and that was the extinction of a species of rat in a very small and remote location (Christmas Island).

Of course, Ord notes, levels of risk from natural pandemics have changed both for the better and for the worse in recent history. On the one hand, we are more vulnerable because there are more of us, and we live in a denser and more interconnected society. On the other hand, we have excellent medicine, technology, and public health to protect us. For example, we saw in Part 10 of this series that simple non-pharmaceutical interventions in Wuhan and Hubei may have reduced cases by a factor of 67 by the end of February 2020, and that for the first time a global pandemic was ended in real-time by the development of an effective vaccine.

So far, we have seen the following: Historical pandemics suggest, if anything, surprising resilience of human civilization to highly destructive events. The fossil record suggests that disease rarely leads to mammalian extinction, and while human society has since changed in some ways that make us more vulnerable than our ancestors were, we have also changed in some ways that make us less vulnerable than our ancestors were. So far, we have been given no meaningful argument for a 1/10,000 chance of irreversible existential catastrophe from natural pandemics by 2100. Does Ord have anything in the way of a positive argument to offer?