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AstraSequi comments on Open thread, Jul. 18 - Jul. 24, 2016 - Less Wrong Discussion
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I have some questions on discounting. There are a lot, so I'm fine with comments that don't answer everything (although I'd appreciate it if they do!) I'm also interested in recommendations for a detailed intuitive discussion on discounting, ala EY on Bayes' Theorem.
On a personal level, my intuition is not to discount at all, i.e. my happiness in 50 years is worth exactly the same as my happiness in the present. I'll take $50 right now over $60 next year because I'm accounting for the possibility that I won't receive it, and because I won't have to plan for receiving it either. But if the choice is between receiving it in the mail tomorrow or in 50 years (assuming it's adjusted for inflation, I believe I'm equally likely to receive it in both cases, I don't need the money to survive, there are no opportunity costs, etc), then I don't see much of a difference.
If you separate utility discount into uncertainty (which isn't actually a discount of a world state, it's weighting across world-states and should be separately calculated by any rational agent anyway) and time preference, it's pretty reasonable to have no utility discount rate.
It's also reasonable to discount a bit based on diffusion of identity. The thing that calls itself me next year is slightly less me than the thing that calls itself me next week. I do, in fact, care more about near-future me than about far-future me ,in the same way that I care a bit more about my brother than I do about a stranger in a faraway land. Somewhat counteracting this is that I expect further-future me to be smarter and more self aware, so his desires are probably better, in some sense. Depending on your theory of ego value, you can justify a relatively steep discount rate or a negative one.
Hyperbolic discounting is still irrational, as it's self-inconsistent.
Thanks for that – the point that I’m separating out uncertainty helped clarify some things about how I’m thinking of this.
So is time inconsistency the only way that a discount function can be self-inconsistent? Is there any reason other than self-inconsistency that we could call a discount function irrational?
Couple of things to throw in there.
First, you can empirically observe real-life discount functions that you can, ahem, bet money on. For example, here.
Second, with respect to "my intuition is not to discount at all", let's try this. I assume you have some income that you live on. How much money would you take at the end of three months to not receive any income at all for those three months? Adjust the time scale if you wish.
In general, you can think of discounting in terms of loans. Assuming no risk of default, what is the interest rate you would require to lend money to someone for a particular term?
If I received an amount equal to the income I would have gotten normally, then I have no preference over which option occurs. This still assumes that I have enough savings to live from, the offer is credible, there are no opportunity costs I’m losing, no effort is required on my part, etc.
This is the same question, unless I misunderstood. I do have a motivation to earn money, so practically I might want to increase the rate, but I have no preference between not loaning and a rate that will put me in the same place after repayment. With my assumptions, the rate would be zero, but it could increase to compensate - if there's an opportunity cost of X, I'd want to get X more on repayment, etc.
No, it does NOT assume that.
Basically you have a zero discount rate for money which you don't need at the moment. How about money which you can use and want to use today, what rate will persuade you to go without?
That assumption is to make time the only difference between the situations, because the point is that the total amount of utility over my life stays constant. If I lose utility during the time of the agreement, then I would accept a rate that earns me back an amount equal to the value I lost. But if I only "want" to use it today and I could use it to get an equal amount of utility in 3 months, then I don't have a preference.
I don't think this is a useful approach. A major component of time preference is the fact that future is uncertain.
If you set up the situation such that there is basically no difference between the future and the present (both are certain, known, you yourself don't change, etc.) then yes, reshuffling utility between two otherwise identical points on a timeline is something you could well be indifferent to. However that's very far away from the real life and I thought we were talking about something with practical applications rather than idealized abstractions.
It actually does have practical applications for me, because it will be part of my calculations. I don't know whether I should have any preference for the distribution of utility over my lifetime at all, before I consider things like uncertainty and opportunity cost. Does this mean you would say the answer is no?
I would say that before your current needs, uncertainty, opportunity cost, and changes in yourself the answer is debatable, that is, I can see it coming down to individual preferences.
But I still don't see practical applications. For actual calculations you need some reasonable numbers and I don't see how you are going to come up with them.
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.
Do you think you actually behave that way on a system one level?
I can think of example where I behaved both ways, but I haven't recorded the frequencies. In practice, I don't feel any emotional difference. If I have a chocolate bar, I don't feel any more motivated to eat it now than to eat it next week, and the anticipation from waiting might actually lead to a net increase in my utility. One of the things I'm interested in was whether there's anyone else who feels this way, because it seems to contradict my understanding of discounting.