In what situation should a longtermist (a person who cares about people in the future as much as they care about people in the present) ever do hyperbolic discounting
Hyperbolic discounting leads to preferences reversals over time: the classic example is always preferring a certain $1 now to $2 tomorrow, but preferring a certain $2 in a week to $1 in 6 days. This is a pretty clear sign that it never “should” be done—An agent with these preferences might find themselves paying a cent to switch from $1 in 6 days to $2 in 7, then, 6 days later, paying another cent to switch it back and get th $1 immediately.
However, in practice, even rational agents might exhibit hyperbolic discounting like preferences (though no preference reversals): for example, right now I might not believe you’re very trustworthy and worry you might forget to give me money tomorrow. So I prefer $1 now to $2 tomorrow. But if you actually are going to give me $1 in 6 days, I might update to thinking you’re quite trustworthy and then be willing to wait another day to get $2 instead. (See this paper for a more thorough discussion of this possibility: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1689473/pdf/T9KA20YDP8PB1QP4_265_2015.pdf)
In theory, never (either hyperbolic time discounting is a bias, and never “should” be done, or it’s a value, but one that longtermists explicitly don’t share).
In practice, hyperbolic time discounting might be a useful heuristic, e.g. perhaps since we are bad at thinking of all the ways that our plans can go wrong, we tend to overestimate the amount of stuff we’ll have in the future, and hyperbolic time discounting corrects for that.
In what situation should a longtermist (a person who cares about people in the future as much as they care about people in the present) ever do hyperbolic discounting
Hyperbolic discounting leads to preferences reversals over time: the classic example is always preferring a certain $1 now to $2 tomorrow, but preferring a certain $2 in a week to $1 in 6 days. This is a pretty clear sign that it never “should” be done—An agent with these preferences might find themselves paying a cent to switch from $1 in 6 days to $2 in 7, then, 6 days later, paying another cent to switch it back and get th $1 immediately.
However, in practice, even rational agents might exhibit hyperbolic discounting like preferences (though no preference reversals): for example, right now I might not believe you’re very trustworthy and worry you might forget to give me money tomorrow. So I prefer $1 now to $2 tomorrow. But if you actually are going to give me $1 in 6 days, I might update to thinking you’re quite trustworthy and then be willing to wait another day to get $2 instead. (See this paper for a more thorough discussion of this possibility: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1689473/pdf/T9KA20YDP8PB1QP4_265_2015.pdf)
In theory, never (either hyperbolic time discounting is a bias, and never “should” be done, or it’s a value, but one that longtermists explicitly don’t share).
In practice, hyperbolic time discounting might be a useful heuristic, e.g. perhaps since we are bad at thinking of all the ways that our plans can go wrong, we tend to overestimate the amount of stuff we’ll have in the future, and hyperbolic time discounting corrects for that.