Time Biases: A Theory of Rational Planning and Personal Persistence

by Meghan Sullivan

Should you care less about your distant future? What about events in your life that have already happened? How should the passage of time affect your planning and assessment of your life? Most of us think it is irrational to ignore the future but completely harmless to dismiss the past. But this book argues that rationality requires temporal if you are rational you don't engage in any kind of temporal discounting. The book draws on puzzles about real-life planning to build the case for temporal neutrality. How much should you save for retirement? Does it make sense to cryogenically freeze your brain after death? How much should you ask to be compensated for a past injury? Will climate change make your life meaningless? Meghan Sullivan considers what it is for you to be a person extended over time, how time affects our ability to care about ourselves, and all of the ways that our emotions might bias our rational planning. Drawing substantially from work in
social psychology, economics and the history of philosophy, the book offers a systematic new theory of rational planning.

Genres: Philosophy, Nonfiction, Economics

208 pages, Hardcover

Published August 28, 2018

Reviews

[Peter McCluskey · Rating 4 out of 5]

I was very unsure about whether this book would be worth reading, as it could easily have been focused on complaints about behavior that experts have long known are mistaken.

I was pleasantly surprised when it quickly got to some of the really hard questions, and was thoughtful about what questions deserved attention. I disagree with enough of Sullivan's premises that I have significant disagreements with her conclusions. Yet her reasoning is usually good enough that I'm unsure what to make of our disagreements - they're typically due to differences of intuition that she admits are controversial.

I had hoped for some discussion of ethics (e.g. what discount rate to use in evaluating climate change), whereas the book focuses purely on prudential rationality (i.e. what's rational for a self-interested person). Still, the discussion of prudential rationality covers most of the issues that make the ethical choices hard.

Personal identity

A key issue is the nature of personal identity - does one's identity change over time?

Sullivan starts this discussion by comparing a single-agent model to a model with multiple distinct stages.

I initially found that part of the book confusing, as neither model seems close to mine, and she seemed to present them as the only possible models. Then somewhat later on in the book, I figured out that both those models assumed that identity needed to stay constant for some time, and that in the case of the multiple stage model, the change in identity was discontinuous.

Sullivan prefers that kind of single-agent model, and therefore concludes that we should adopt a time-neutral stance (i.e. she rejects any time-discounting, and expects us to care as much about our distant future selves as we care about our present selves).

Sullivan eventually compares that single-agent model to some models in which a current self partially identifies with a future self, which would allow for time-discounting of how much we care about a self.

The most interesting of those models involves some notion of connectedness between current and future selves.

This feels like the obviously right approach to me. I expect it to work something like the "me" of a decade ago or a decade in the future being something I consider to be maybe 75% "me". I.e. I practice time-discounting, but with a low enough discount rate that it might be hard to distinguish from no discounting in many contexts.

Sullivan looks at some possible measures of connectedness, and convinces me that they don't explain normal attitudes toward our future selves.

I suggest that she's too quick to give up on her search for connectedness measures. I think the things which cause me to care about my future self more resemble what causes me to feel connected to friends, so it should include something like the extent to which we expect to interact. That includes some measures of how much my present self interacts with my future self. I don't have anything resembling a complete model of how such connectedness would work, but I'm fairly confident that people do use some sort of connectedness model for deciding how much to identify with future selves.

Sullivan argues that concern-based discounting of future selves would require changes in how we evaluate our age (e.g. if my two-year-old self wasn't connected enough with my current self, then there's something wrong with starting at birth to count my age). I agree that it implies there's something imperfect about standard answers to "how old am I?", but it seem perfectly reasonable to say we want easily checkable answers to how old we are, even if that discards some relevant information. ("All models are wrong, but some are useful").

If Sullivan can misunderstand our models of how old we are, then it's easy to imagine that she's made a similar mistake with how much we should care about existence over time - i.e. Sullivan sees that it's useful to treat people as time-neutral for the purpose of, say, signing contracts; whereas for other purposes (e.g. do people save enough for retirement?), I see people caring less about their future selves. It seems likely that time-neutrality is a good enough approximation for most of our activities, which rarely require looking more than a decade into the future. Yet that doesn't say much about how to model substantially longer time periods.

It's more common for people to discount the future too much than too little, so it's often wise to encourage the use of models with less discounting. That creates some temptation to go all the way to zero discounting, and doing so may be a good heuristic in some cases. But it produces weird results that I mention below.

Caring about the past
Sullivan devotes a substantial part of the book to arguing that it's meaningful to have preferences about the past, and that rationality prevents us from discounting the past.

An example: people who sue in response to an accident that caused them pain will ask for more compensation if asked when they're in pain than if they're asked when the pain is in the past.

Sullivan provides other examples in the form of weird thought experiments about painful surgery followed by amnesia, where I might be left uncertain about whether the pain is in my past or my future.

No one example seems convincing by itself, but there seems to be a real pattern of something suspicious happening.

Sullivan convinced me that preferences about the past mean something, and that there's something suspicious about discounting the past - unless it follows the same discounting rules as apply to the future.

But I don't find it helpful to frame problems in terms of preferences about the past. Timeless decision theory (TDT) seems to provide a more natural and comprehensive solution to these kinds of problems, and assumes time-neutrality, or a discount rate that's low enough to approximate time-neutrality over the relevant time periods. (I'm unsure whether TDT is understood much beyond the rather specialized community that cares about it).

Sullivan's approach seems to leave her puzzled about Kavka's toxin puzzle. It seems that something in her premises implies that we can't become the kind of person who follows TDT (i.e. follows through on a commitment to drink the poison), but I haven't quite pinned down what premise(s) lead her there, and it seems to leave her in a position that looks time-biased. Specifically, she seems to imply that there's something irrational about making a time-neutral decision to drink the poison. Yet in other parts of the book, she says that our decisions shouldn't depend on what time we happen to find ourselves located at, assuming all other evidence available to us remains the same.

Sullivan is careful to distinguish care for the past from the sunk cost fallacy. One relevant question is: did I get new info which would have altered my prior self's decision? Another approach is to imagine what an impartial observer would say - that helps make it irrelevant whether an event is in my past or my future. I probably missed some important nuance that Sullivan describes, but those seem like the important distinctions to make.

Afterlives
How should we think about really long lifespans?

Sullivan uses a strange (but harmless?) concept of afterlife, which includes any time experienced after an "irreversible radical change", e.g. heaven, dementia, or quadriplegia.

A key claim (which I'll abbreviate as SALE) is:

The Simple Approach for Life Extension: it is rationally permissible (and perhaps rationally obligatory) to prefer some potential future state of affairs A over some potential future state of affairs B if A has greater aggregate expected well-being than B.

I reject the obligatory version of this claim, because I discount future well-being. If I adopted the time-neutrality that Sullivan endorses, I'd endorse the obligatory version of SALE.

Sullivan is uncomfortable with SALE, because it leads to the "single life repugnant conclusion". I.e. that a sufficiently long life of slightly positive well-being is better than a short life with more well-being. She doesn't describe a good reason for a time-neutral person to find this repugnant, so I'm inclined to guess that she (and most people) find it repugnant due to a (possibly unconscious) preference for time discounting.

My reluctance to endorse the single life repugnant conclusion seems to be purely a function of my caring more about near-future versions of myself than about distant-future versions.

Sullivan doesn't seem to identify anything repugnant about the conclusion beyond the fact that it feels wrong. So I'm left guessing that her intuitions of repugnance result from intuitions that distant future selves are less important.

She can, of course, believe that those intuitions are irrational, and that she's trying to overcome them. But then why doesn't she also try to overcome the feelings of repugnance about the single life repugnant conclusion?

Sullivan describes another version of SALE's consequences, asking us to imagine that hell has enough breaks in the torture that it yields an average positive balance of well-being, for eternity. It looks to me like she's trying to prejudice our intuitions with words that suggest a life that's worse than non-existence, and then contradicting that impression when she gets more specific. I don't see what the substance of her objection is here.

It seems my main disagreement with Sullivan boils down to the choice between:
A) agreeing that we will care less about distant future versions of ourselves than near future versions (i.e. accept something like time-discounting),
or
B) running into repeated conflicts between our intuitions and our logic when making decisions about time-distant versions of our selves.

Either choice appears to produce ordinary results when dealing with relatively familiar time periods, and strange results when applied to unusually long time periods. Choice A seems a bit simpler and clearer.

Conclusion

The book is mostly clear and well-reasoned, with a few important exceptions that I've noted, and those exceptions are about topics that seem to confuse most philosophers who tackle them.

I expect that many people will learn something important from the book, but it caused me to mostly just reinforce my existing beliefs.

[Matt Berkowitz · Rating 3 out of 5]

An interesting, thought-provoking read for a more academic, technical audience. But it’s not too jargon-filled such that you’re likely to get lost in it, and when Sullivan does use jargon, she clearly defines the term and provides practical examples.

Her main thesis is that time biases are irrational. By “rational”, Sullivan means “prudential approbative rationality” which “concerns reasoning about your preferences given your self-interest.”

By “time bias”, she means “systematic preferences about when events happen” and claims that “there is good reason to think that all time biases are irrational” (Introduction). She further promises that “[l]earning to recognize and overcome our irrational time preferences can help us become better planners.” This struck as a very contentious claim. I thought, “Sure, many time biases are irrational, but surely not all systematic preferences about when events happen are irrational. Should the proper discount rate for the future (adjusted for inflation) really be zero?

So my skepticism was tuned high and I read with interest to see if my position would be shifted.

The crux of her argument and responses to anticipated objections are contained in chapter 2, so that will be my main focus for this brief review.

2.2 Life-Saving Argument:

“(1) At any given time, a rational agent prefers that her life going forward go as well as possible.
(The Success principle)
(2) If you are near-biased, then in distant tradeoffs you will prefer and choose the present,
lesser good over the greater, future good.
(3) Your life going forward would go better if you preferred and chose the greater, future good
in a distant tradeoff.
C. So near-biased preferences are not rationally permissible, insofar as you face a distant
tradeoff choice.”

To me, (3) seems like begging the question. If your life will be better off, surely it’s irrational to do it given Sullivan’s definition of rational (choosing things given self-interest). But Sullivan anticipates this objection: “You might worry that, as stated, [the Success] principle assumes future neutrality, since it requires concern for future success. But Success alone does not entail future neutrality, because the Success principle alone is silent with respect to how we define the future good.” I don’t find this particularly satisfying. In the Introduction, Sullivan defines time biases as systematic preferences about when events happen. The above syllogism adds a caveat about a counterfactual scenario in which your life would be better off. The greater the difference between the future good and present good—however “good” is defined—the more irrational it would be to be near-biased. The crux here, for me, is the uncertainty about the future and the difficulty in knowing or estimating what the future good will be.

Sullivan touches on this later (2.5 Bookstore Buddhism): “If we are very uncertain of the future, we account for this using probabilistic discounting.” This for me negates the contentiousness that all time biases are irrational and even seems rather contradictory. If we ought not have any preference for when things happen (i.e., the correct discounting rate is zero), yet the real world always challenges us to make decisions under uncertainty (and therefore it’s acceptable to use probabilistic discounting), haven’t we just collapsed the whole issue into a practical/statistical question of how best to estimate this probability function?

To the extent that the claim “time biases are irrational” is contentious (when defined as mere preferences for when events occur), ignoring expectations, adjustments, and uncertainty for future goods, the claim seems false; to the extent that the claim refers to such preferences after having done probability discounting, the claim seems trivial and hardly in need of much defense.

After Chapter 2, most of the material is very interesting but deals mostly with tangential issues to her main thesis (she deals with the “Arbitrariness Argument” and “Personal Volatility” in chapters 3 and 4, respectively). Though some chapters do elucidate the main thesis.

Chapters 5-7 discuss preferences and purposed biases about events that took place in the past. Sullivan uses Derek Parfit’s amnesia thought experiment regarding a painful surgery having occurred in the past vs still yet to occur in the future:

“I have just woken up. I cannot remember going to sleep. I ask my nurse if it has been decided when my operation is to be, and how long it must take. She says that she knows the facts about both me and another patient, but that she cannot remember which facts apply to whom. She can tell me only that the following is true. I may be the patient who had his operation yesterday. In that case, my operation was the longest ever performed, lasting ten hours. I may instead be the patient who is to have a short operation later today. It is either true that I did suffer for ten hours, or true that I shall suffer for one hour.

I ask the nurse to find out which is true. While she is away, it is clear to me which I prefer to be true. If I learn that the first is true, I shall be greatly relieved.”

I think Sullivan’s ensuing discussion—which references discounting functions about the past—is interesting but far from satisfying. I think one would have to take into consideration distinctions like Kahneman’s “remembered self” and “experiencing self” to be able to reliably assess whether one’s preferences are rational. If some terrible physical pain occurred in my past, but I can’t remember it and it leaves no physical marks on me today, wouldn’t it make sense to prefer it over a future yet-to-be-experienced lesser pain? In her analysis, Sullivan doesn’t much reference the amnesia, but I think it ought to heavily weigh into one’s preferences.

In Chapter 6, Sullivan contrasts Parfit’s thought experiment with a “Crossfit” thought experiment, in which a someone who has exercised for 45 minutes entirely discounts the past suffering simply because it’s in the past. Sullivan’s lesson is that “[w]hen we reason about the cases directly (as in Parfit’s surgery case), we are disposed to discount past experiences absolutely. But when asked to set an exchange rate for past experiences, many of us think they can be compensated with other goods.” But this again ignores the amnesia property, which seems critical to me. Discounting one’s suffering in the Crossfit experiment might become slightly more rational if one had amnesia surrounding the exercise (and didn’t feel the physical effects of having exercised). The trade-off does not seem entirely relevant to me in what makes the two cases so different.

That said, I do agree with the thrust of Sullivan’s “Mixed Tradeoff Argument” which argues that one should be indifferent to a trade-off between A and B (a hedonic good and hedonic bad) regardless of whether that trade-off occurs in the past or the future. However, I do object to her later argument about a diner who regrets agreeing to pay $50 for a restaurant meal once the meal is over and the experience is in the past. Sullivan contends that “[t]he only way to avoid committing herself to a deal she knows she will come to regret is to commit to being temporally neutral about the value of the experience.” This doesn’t seem imaginative enough to me, and perhaps is indicative of a too narrowly philosophical take. I think one has to invoke economics to overcome the regret: We recognize that in order to be able to have future pleasurable dining experiences (i.e., for the market to provide such opportunities to us), we ought to still value the experience.

I’ll stop there with the responses to arguments…

On the whole, this was an enlightening, thoughtful read, even though I disagreed with many of the arguments. The writing is generally clear, albeit technical and sometimes a bit hard to parse for the non-philosopher (i.e., me). Worth a read if this topic interests you.

[chawon · Rating 3 out of 5]

I have so many objections to each chapter of this book. There were too many moments where I felt I had lost my sympathy for Sullivan's project. Still, the overarching ideas are worth thinking about.

[Lukasz]

mentioned via https://80000hours.org/podcast/episod...