Even a comparatively low pure discount rate of 1% implies most future value is concentrated in the next hundred years
This is not correct! Suppose the human population grows at a constant rate for 1000 years. If you discount the moral worth of future people by 1% per year, but the growth rate is anything above 1%, most of the value of humanity is concentrated in the last hundred years, not the first hundred years.
There’s this very surprising, maybe counterintuitive moral implication of cosmopolitanism where if you think future people have moral value and you believe in discount rates of 1-3%, you should basically disregard any present-day considerations and make all of your decisions based solely on how they affect the distant future, but if you use a discount rate of 5%, you should help one person today rather than a billion trillion people a thousand years from now.[1]
This is not correct! Suppose the human population grows at a constant rate for 1000 years. If you discount the moral worth of future people by 1% per year, but the growth rate is anything above 1%, most of the value of humanity is concentrated in the last hundred years, not the first hundred years.
There’s this very surprising, maybe counterintuitive moral implication of cosmopolitanism where if you think future people have moral value and you believe in discount rates of 1-3%, you should basically disregard any present-day considerations and make all of your decisions based solely on how they affect the distant future, but if you use a discount rate of 5%, you should help one person today rather than a billion trillion people a thousand years from now.[1]
https://www.wolframalpha.com/input?i=1000000000000000000000*0.95%5E1000.0
Hi Robi,
The answer was assuming a constant population rather than a growing population, although (confusingly) that assumption was not made explicit.
However, I hadn’t appreciated the points you make in the second paragraph. That’s very interesting.