I agree that in short-term contexts a discount rate can be a reasonable pragmatic choice to model things like epistemic uncertainty, but this seems to somewhat obviously fall apart on the scale of tens of thousands of years. If you introduce space travel and uploaded minds and a world where even traveling between different parts of your civilization might take hundreds of years, you of course have much better bounds on how your actions might influence the future.
I think something like a decaying exponential wouldn’t seem crazy to me, where you do something like 1% for the next few years, and then 0.1% for the next few hundred years, and then 0.01% for the next few thousand years, etc. But anything that is assumed to stay exponential when modeling the distant future seems like it doesn’t survive sanity-checks.
Edit: To clarify more: This bites particularly much when dealing with extinction risks. The whole point of talking about extinction is that we have an event which we are very confident will have very long lasting effects on the degree to which our values are fulfilled. If humanity goes extinct, it seems like we can be reasonably confident (though not totally confident) that this will imply a large reduction in human welfare billions of years into the future (since there are no humans around anymore). So especially in the context of extinction risk, an exponential discount rate seems inappropriate to model the relevant epistemic uncertainty.
Perhaps worth noting that very long term discounting is even more obviously wrong because of light-speed limits and the mass available to us that limits long term available wealth—at which point discounting should be based on polynomial growth (cubic) rather than exponential growth. And around 100,000-200,000 years, it gets far worse, once we’ve saturated the Milky Way.
Hyperbolic discounting, despite its reputation for being super-short-term and irrational, is actually better in this context, and doesn’t run into the same absurd “value an extra meal in 10,000 years more than a thriving civilization in 20,000 years” problems of exponential discounting.
Here is a nice blog post arguing that hyperbolic discounting is actually more rational than exponential: hyperbolic discounting is what you get when you have uncertainty over what the correct discount rate should be.
I agree that in short-term contexts a discount rate can be a reasonable pragmatic choice to model things like epistemic uncertainty, but this seems to somewhat obviously fall apart on the scale of tens of thousands of years. If you introduce space travel and uploaded minds and a world where even traveling between different parts of your civilization might take hundreds of years, you of course have much better bounds on how your actions might influence the future.
I think something like a decaying exponential wouldn’t seem crazy to me, where you do something like 1% for the next few years, and then 0.1% for the next few hundred years, and then 0.01% for the next few thousand years, etc. But anything that is assumed to stay exponential when modeling the distant future seems like it doesn’t survive sanity-checks.
Edit: To clarify more: This bites particularly much when dealing with extinction risks. The whole point of talking about extinction is that we have an event which we are very confident will have very long lasting effects on the degree to which our values are fulfilled. If humanity goes extinct, it seems like we can be reasonably confident (though not totally confident) that this will imply a large reduction in human welfare billions of years into the future (since there are no humans around anymore). So especially in the context of extinction risk, an exponential discount rate seems inappropriate to model the relevant epistemic uncertainty.
Perhaps worth noting that very long term discounting is even more obviously wrong because of light-speed limits and the mass available to us that limits long term available wealth—at which point discounting should be based on polynomial growth (cubic) rather than exponential growth. And around 100,000-200,000 years, it gets far worse, once we’ve saturated the Milky Way.
Hyperbolic discounting, despite its reputation for being super-short-term and irrational, is actually better in this context, and doesn’t run into the same absurd “value an extra meal in 10,000 years more than a thriving civilization in 20,000 years” problems of exponential discounting.
Here is a nice blog post arguing that hyperbolic discounting is actually more rational than exponential: hyperbolic discounting is what you get when you have uncertainty over what the correct discount rate should be.