Are any types of non-exponential discounting time-consistent?
No.
Why do people focus on hyperbolic and exponential? Aren’t there other options?
I don’t think people really mean anything very specific by “hyperbolic discounting.” They are just considering a 3 period model and saying that anything other than exponential is inconsistent. The qualitative form of hyperbolic discounting—of falling rapidly at first, and then slowly—empirically matches human psychology, but I don’t think people care very much about precisely what inconsistent preferences humans express.
Yeah, this is what I suspect, too. “Hyperbolic” is just a metaphor, a simple example of a curve that has the required properties. There is probably no hyperbolometer in the emotional center of the human brain.
No.
I don’t think people really mean anything very specific by “hyperbolic discounting.” They are just considering a 3 period model and saying that anything other than exponential is inconsistent. The qualitative form of hyperbolic discounting—of falling rapidly at first, and then slowly—empirically matches human psychology, but I don’t think people care very much about precisely what inconsistent preferences humans express.
Yeah, this is what I suspect, too. “Hyperbolic” is just a metaphor, a simple example of a curve that has the required properties. There is probably no hyperbolometer in the emotional center of the human brain.