Comment on 'The discount rate is not zero'

Abstract

Longtermists believe that future people matter, there could be a lot of them, and they are disenfranchised. They argue a life in the distant future has the same moral worth as somebody alive today. This implies that analyses which discount the future unjustifiably overlook the welfare of potentially hundreds of billions of future people, if not many more.Given the relationship between longtermism and views about existential risk, it is often noted that future lives should in fact be discounted somewhat – not for time preference, but for the likelihood of existing (i.e., the discount rate equals the catastrophe rate).I argue that the long-term discount rate is both positive and inelastic, due to 1) the lingering nature of present threats, 2) our ongoing ability to generate threats, and 3) continuously lowering barriers to entry. This has 2 major implications.First, we can only address near-term existential risks. Applying a long-term discount rate in line with the long-term catastrophe rate, by my calculations, suggests the expected length of human existence is another 8,200 years (and another trillion people). This is significantly less than commonly cited estimates of our vast potential.Second, I argue that equally applying longtermist principles would consider the descendants of each individual, when lives are saved in the present. A non-zero discount rate allows us to calculate the expected number of a person’s descendants. I estimate 1 life saved today affects an additional 93 people over the course of humanity’s expected existence.Both claims imply that x-risk reduction is overweighted relative to interventions such as global health and poverty reduction (but I am NOT arguing x-risks are unimportant).