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A better way to divide the pie (yale.edu)
129 points by geox on March 20, 2022 | hide | past | favorite | 102 comments


One thing I learned in a class on negotiation was that many people look at negotiation as a one-time thing. Examples like buying a car happen for most buyers once every 5 to 10 years. It is also a negotiation that most often happens with a new sales agent / sales manager combo for every transaction.

However, a large number of negotiations in business happen with the same group of people over and over again. The example was a set of directors in a large org negotiating over budget. That kind of thing might happen every single business quarter between a stable set of peers.

Whenever I see strategies like these I consider those two cases since they have influence on how negotiations are done. In the car-sales case, there is an incentive to get the most out of the individual negotiation since you almost certainly will never see each other again. In the business case you are incentivized to prioritize the relationship with your peers over any individual negotiation.

So I don't agree with the simplistic conclusion in the article. It seems to only consider fairness within the context of a single transaction/negotiation. It does not consider what happens when this strategy is repeated between actors across multiple negotiations.


> Whenever I see strategies like these I consider those two cases since they have influence on how negotiations are done. In the car-sales case, there is an incentive to get the most out of the individual negotiation since you almost certainly will never see each other again. In the business case you are incentivized to prioritize the relationship with your peers over any individual negotiation.

Very insightful point.

The biggest salary negotiation mistake I see is when people assume the negotiation is of the first type (one-off, never see people again) instead of the latter type (part of an ongoing relationship).

If a company works hard to minimize someone's compensation expectations and convince them to accept below-market salary, they're going to pay for it later when the person wises up and leaves for something better. This scenario is well-known.

The less discussed scenario is when a candidate aggressively negotiates a very above-average compensation but subsequently performs in a below-average manner. This is one of the most common complaint scenarios in a private manager forum that I'm part of: Managers who get wowed by people with excellent interviewing and self-selling skills who end up underperforming their lesser-paid peers later. It generates a lot of guilt and anxiety for managers when they realize they've been duped into inverting the contribution:reward relationship in their compensation structure.

These people are the first to go in any downsizing, reorgs, and layoffs (and rightly so), but they're often great at talking their way into the next highly paid job almost immediately. This is one of the main reasons experienced managers will go extra deep on reference checks for people with job-hopper resumes.


> The less discussed scenario is when a candidate aggressively negotiates a very above-average compensation but subsequently performs in a below-average manner. This is one of the most common complaint scenarios in a private manager forum that I'm part of: Managers who get wowed by people with excellent interviewing and self-selling skills who end up underperforming their lesser-paid peers later. It generates a lot of guilt and anxiety for managers when they realize they've been duped into inverting the contribution:reward relationship in their compensation structure.

Isn't this more a failure of the management? What can justify having wide disparities in starting comp for the same role? Seems like the striving candidate should be bumped up a level & you just hold them accountable to the higher bar, rather than evaluating their performance based on comp.


That's the point - If you bring someone in at the wrong level (higher comp = higher level) then you have a major problem.

Compensation does vary within a role, though. Even at organizations that publicly share salary info there is often a wide range within each band and the salary bands may overlap.

Paying everyone in perfect lock-step with each other sounds great in theory, but you end up either paying significantly more than you need to or locking yourself out of otherwise great hires that were just a few thousand short of your fixed salary. Obviously, not everyone within a role performs exactly the same.


> The biggest salary negotiation mistake I see is when people assume the negotiation is of the first type (one-off, never see people again) instead of the latter type (part of an ongoing relationship).

That depends what you're negotiating. As a counterexample, if you negotiate a big raise upfront for your promotion and then "coast" for 5-10 years, you're still better off than negotiating a series of smaller raises every 2 years, because you forego the overhead of multiple negotiations. Personally, I'd rather just focus on the work.

Negotiation is costly if you're not good at it. It's easier to justify your value once, than multiple times. Due to anchoring, and people getting used to the increased output you bring, it will become harder and harder to negotiate as you go further.

Better to do it once, but do it right.


Do those managers ever self-reflect and give raises to their less polished, better performing employees?


I prefer the way my company does it. There is no negotiation. Roles are fixed and everyone in the same role makes the same amount of money. If you get hired for a certain role you will make the associated salary and not a dollar more or less.


That will incentivize me to work only as hard as the lowest-performing colleague in the same role.


Which also might be fine. Trying harder doesn’t always lead to more useful work done, you might be better at your job if you’re more relaxed and don’t overwork yourself, and if your motivation of work is to keep up with an image of how other people work there’s a good chance you won’t be as good as an employee who cares about doing work well because they care more about quality than quibbling about fairness.

Sometimes people don’t do as much or as well for things that are none of your business and if that becomes an incentive problem for you, you’re the problem.


> One thing I learned in a class on negotiation was that many people look at negotiation as a one-time thing. Examples like buying a car happen for most buyers once every 5 to 10 years. It is also a negotiation that most often happens with a new sales agent / sales manager combo for every transaction.

You may have been implying this already, but just to reinforce the message: it's an asymmetric event frequency.

For the buyer, it occurs once every few years. For the seller, it's occurring on a weekly or perhaps daily basis.

That means that the seller is fairly likely to know most of the common weaknesses and opportunities for buyers, and the ways in which those buyers communicate (or fail to communicate) them. Sellers can choose to do what they want with that information advantage.

To me the question is a broader one: why are Alice and Bob accepting to enter into some byzantine challenge where they have to co-operate in order to receive a larger amount of pizza? And why is there an entire book for sale on the topic, when at first-glance it seems to closely (~80%) resemble what can be defined as the prisoners' dilemma within a paragraph?

I think Alice and Bob should publish the ridiculous situation they've been faced with at the pizza restaurant and find somewhere else to go to eat, and I don't think they require a book to teach them that.


I can’t quite tell if you’re missing the point. The pizza analogy is just some simple case that’s easy to explain in a paragraph. The book is on negotiations, so they need some easy case to negotiate.

I’ve had to negotiate for my team at work before and one common thing I hear at private discussions with other parties when in planning for the meetings is that it’s backwards and toxic to have business politics and they want to leave the team over it. this feels like you’re take - and it misses the point that today, you have to accomplish some task. Even if you’re against politics at work, you’re beholden to them once they start. Tomorrow is for deciding if you should accept reality or make changes. And some things aren’t likely to go away.


Generally I think my perspective on the issue is that a lot has been written already, and that people have a tendency to rewrite and bring-to-market content that is a rehash of existing knowledge, as opposed to gathering people together towards consensus (and expansion, and critique) of existing best-known information. Perhaps writing books is an expression of that; and perhaps my frustration is because I wonder whether we could do better in the digital age.

In the context of workplace politics: again, these are all patterns that have been repeated for generations. Perhaps it's possible to document and make those patterns public, and then help people to view and decide upon the kind of workplace(s) they'd like to contribute to.


This is throughly discussed in game theory. Single games, finitely repeated games, infinitely repeated games.


There is only one infinite game.


Can you explain? A reference to Carse?


+1. It is hard to read articles like this about contemporary economics research without having “first, assume a spherical cow” pop into my head.


Or, as in this case, "first, assume a pizza parlor owner who, when two people cannot agree on how to split up the whole (which they presumably already paid for) will give them just half a pie, but asymmetrically allocated".

Sheesh. What real world scenario is this supposed to model?


A situation where if two people cooperate, they both benefit, but if they don’t, they each benefit less?

These types of situations happen all the time. Think of two businesses collaborating on a project, for example.


>there is an incentive to get the most out of the individual negotiation since you almost certainly will never see each other again

You've got great insights here. That said, I can't help but think that perception - that it is a one-time, transaction relationship - is a key difference between winners and losers. What I mean is, from the standpoint of the salesperson, they should be seeking a long-term win and not just a win in this transaction. We'll use your example of a car, but I can think of many other places where this also applies. In the the car situation - you really want to sell / lease them the car, but you also want there services business. You want them to tell their friends to come buy from you. You want them to come back in 5-10 years and buy/ lease their next car from you. None of that happens if they walk away feeling like it wasn't a fair situation.

Likewise, even in a seemingly "done" negotiation, things have a way of cropping up. Like the buyer comes to take possession of the car and decides that the tires look more worn than what they believe, and suddenly want to renegotiate. Or, maybe you've agreed on price already, have started signing the paperwork, but then the salesperson wants to upsell you on the truecoat. Point being - I think you were even more right than you may have intended, in terms of the ongoing nature of negotiations rather than a fixed-position scenario.


this is game theory 101 too. The prisoner’s dilemma is a simple game, like tic tac toe, and the only correct move is to betray the other player every time. But repeated prisoners dilemma is a much more complicated game about trying to get as much out of your opponent as possible without breaking down cooperation altogether.


I like the way you say that. I was going to say that Ann can push to split the pizza 7-5 if it is OK that she is being an a@#hole. If not, she should split it 6-6.

I think the author makes a good point in the article, but he should have at least mentioned future ramifications.


The lack of context in the original deal is such that it might make sense to call Alice an "a@#hole" for not agreeing to 50/50, but I don't thinks that's the case in any real-world example of this.

Why was Alice being offered 4 and Bob 2? Perhaps Alice had done twice as much work as Bob to get the original pizza. Perhaps she had invested twice as many resources. In that case, why would the "fair" deal be one in which Bob is suddenly getting the same compensation as Alice?

The solution outlined in the article makes more sense.


The pizza parlor owner is simply invented as an all-powerful force in the universe, with the capability to decide on the fallback positions. It is totally unclear to me what real-world scenario this is supposed to refer to.


There are many scenarios where joining forces results in higher returns. If my investment is larger, how should we split the profit?


this reminded me of: Evolution of trust

https://ncase.me/trust/


This reminds me of how I used to split rents with my roommates: Identify surplus value, and split that value evenly.

0. Given a prospective rental house. (And therefore a known set of rooms and a known total rent)

1. Each person "bids" by pricing every room in the house. Goal: each person should be looking for "break-even" pricing. Try to price such that all the rooms feel "equally good" at your given prices.

2. Just one restriction on the pricing: each bidder's room-prices must sum to the house's monthly rent.

3. Reveal all bids.

4. Choose the room-assignment that yields the highest total price. Because of the restriction in [2], we're guaranteed a surplus over the true total rent. (Unless everyone somehow put in identical bids)

5. Split the surplus evenly. Everyone gets a room at the price they bid for that room, minus 1/nth of the surplus. Effectively, everyone gets an identical surprise discount.

We lived together for over 10 years, through 5 different rentals. We split up when it came time to start families and buy houses.


0: Total rent is $10, for ten rooms, to be split among ten people.

1: One person who really wants a certain room bids $10 on it, and he assigns $0 to the nine other rooms. His roommates bid a neutral $1 on all rooms.

...

4: The person gaming the system gets his special room.

5: The surplus is $10 + 9*$1 - $10 = $9. Split evenly, $0.90.

Thus, the gamer pays $9.10 for his special room, and everyone else pays $0.10 for their rooms.

He has clearly made a terrible mistake. He's covering the cost of the entire rental nearly by himself.

Next time, he bids $1 + one gummy bear on his special room, and he bids $1 on the other rooms. He imagines that now he'll merely have to buy one gummy bear every month, split it in ten, and give everyone a slice. He's outwitted his roommates, he thinks.

However, much to his dismay, he overlooked that one of the rooms in this next rental was underground. Furthermore, the room was next to a leaky sceptic tank. Everyone else bid $0 on it. The gamer handily wins the sewage room, instead of his special room, and he hardly gets any discount for putting up with it. Oops, foiled again.

All of this is to say, your system seems robust. There's danger in over and underbidding on your assessment of a room's value. You want to be very careful in deciding how much a room is worth to you. I think I'll use this system for renting Airbnb's with friends in the future. Thanks!


Much like with underutilized amusement park rides, the system must accept 'negative' value on some queues (lost guest displacement time in that case) to correctly price the value of the desired outcomes.

As far as the 'sewer room' option goes, I think it would have to be priced at the cost of renting somewhere else; so a negative value.

For the split on the surplus rent there are a couple solutions to this.

IIRC it might be a dutch auction rule? The one where if N of a thing are available a there are N winning bidders all the winning bidders pay the lowest price? Take that rule except apply it to the lowest choice total among the set that yields a full rent.

There's also an argument about how to split the savings. In the 10 + 9 * 1 scenario the portion of the total rent the distribution of savings might be better split up as:

'refund' = SURPLUS * nROOM / (RENT + SURPLUS)

nRENT = nROOM - SURPLUS * nROOM / (RENT + SURPLUS)

If A = 10 and B..J are all 1

5.263... = aRENT = 10 - 9 * 10 / 19

0.526... = xRENT = 1 - 9 * 1 / 19

Rent (10) == A (5.26315789474) + Everyone else (4.73684210526)

Even in the pathological case offered this works well enough.


This sounds like a really great system, although I feel like it doesn't deal with edge-cases.

For example: suppose the total rent is $100 for 4 rooms of varying qualities. I have very little money, so I'm willing to take the terrible cupboard-under-the-stairs room for $15.

I have no way to arrange my bids to say that I can't afford more than $15, since the average of all my bids needs to be $25.


I think a modification to the rules would fix this: you don't have to make all your bids sum to $100. You bid what a room is worth to you, in your case capped at $15. If, after rooms are assigned, the grand total is less than total rent, the lot of you are too broke to afford the place, and you'll have to look for a cheaper alternative.


Whereas a conversation with your prospective roommates might have resulted in them agreeing that nobody wanted the cupboard under the stairs, so they could precommit to allowing your $15 rent and making their bids sum to $85 for three rooms.

The problem with game-theorist economists is that they always neglect long-term externalities because they're messy. Having a reputation as a decent human being is a long-term externality that's very messy.


I was trying to think of an alternative example; the initial condition (the fallback) seems kind of contrived.

So let's say there's some investment opportunity where someone has $4,000 to put in and I have $2,000. The investment requires $6000, so neither of us can access it alone. If we agree to invest, let's say the value is guaranteed to increase, in this example by 200% to $12,000. The power analysis way of distributing that increase would be that the other person gets $8000 and I get $4000. Using this pizza analysis, it would instead be distributed as $7000 and $5000 -- splitting the increase of $6000 equally.

It's an interesting concept. Certainly I, with only $2000, would be more inclined to contribute. And the other party would certainly benefit more than if we had decided to not go through with it at all.

I think it comes down to how much the person with the weaker power is likely to want to contribute. It's a good way to convince them if the power is fairly offset, but when they are close it's not really necessary to convince them.

I think this is partially touched on in the article itself, and it makes sense. It comes down to what seems fair to the parties involved!


Thanks for the more concrete example—the pizza situation in the article seemed really contrived and unintuitive to me! One question this leaves me with and I don’t think the article addresses is what happens when losses are sustained when collaborating. Your stock example provides a good basis for an exploration of this question.

Say A puts $4000 in and B puts $2000 in with the expectation that they will double their money, but instead they lose it all. By the procedure outlined in article, the “pie” worth -$6000 would be evenly distributed, meaning both A and B would have to pay $3000. So A ends up with $1000 and B ends up with -$1000. This seems especially punitive to B, and they end up in a worse place than they would have with what the article calls the “power” arrangement, under which they would have $0 after losing only $2000 instead of $3000.

I’m curious about how many weaker parties continue to favor the “pie” method when losses are divided the same way as gains—-my intuition is that a “pie”-style deal is typically reached only when there is an almost-certain probability of gain, but I’m curious about how negotiators actually behave!


There is a whole subcategory of behavioral economics that can be summed up as "people treat potential losses and potential gains very differently". But what you're saying isn't the example that is being presented. You have A and B being equal partners with a loan from A to B of $1000. That's different from the kind of ultimatum style (with 100% certainty) game that is proposed.

I would say a better example is that A owns 66% of a startup and B owns 33%. They decide to sell the tech for X dollars. However, they are offered a 2X buyout if both of them agree to work for 3 years at the acquiring company. There's no "partial" offer though, it's both partners or neither. How is the 2X split up?

The contrived example fails because of the 33% and 66% wouldn't be assigned randomly.


Without knowing much about the field, intuitively this seems reasonable. More potential return on your money generally means taking a higher risk (more volatile stock = more potential returns). The higher risk here means loosing a higher percentage of your investment (in fact >100%).


I actually think the method proposed in the article works perfectly in this case as well.

If you found a magic investment that was guaranteed to return 200%, but were some money short so couldn't invest at all, if I made up the difference and said we had to split the gains evenly it would still be in your best interests to say yes.

Of course the obvious response is that investments aren't guaranteed to return money. Going by this method, the losses would be "split" evenly as well rather than in proportion. So if the company could only return 50% of the initial investment, you would claim extra money towards your principal, thus reducing your overall risk at the expense of the person who invested less money.


This is a good line of questioning. I believe that the difference between the two situations is that the pizza deal is implied to be just for Alice and Bob. If either walks away then the deal is totally sunk, so they both have equal "leverage" over the deal.

When you frame it as an investment question, the implication is that if either person walks away then they can be replaced by a third party who is willing to stake the cash. Since it is easier to replace someone when their stake is lower, the person putting up the $2k has less leverage in this case.

If you explicitly limited the investment to two specific people (imagine a crazy term in a will or something), then I think you'd end up back with a $7k/$5k split.


Definitely agree, a big part of this is also how badly the person putting more into it needs that other partner.


This example system starts falling apart as the amounts shift. If one party has 5999, and the other 1 dollar, is that type of split still fair? It would never benefit anyone to be the higher of the contributors, a system of everyone looking for suckers.


If there really were a contrived scenario where exactly two people are allowed to contribute, the full 6k does need to be provided, and one person has no means to exceed 5999 then the split is still fair in some sense (and is the only "fair" allocation in the sense described by Shapley -- efficient, symmetric, and linear).

What you're seeing in this hyperbolic "counter-example" is that the assumptions of that model don't hold; the person providing 1 rather than 5999 is probably very replaceable and would be willing to settle for much less profit due to market forces, the person providing 5999 probably has the means to at least temporarily acquire another 1, the deal probably wouldn't fall through in the first place if it were for slightly less than 6k, and so on.


No, of course not. That's why I pointed out that at the end of the day it comes down to what seems fair, and what the two parties are willing to negotiate.


If I were the $4000 person, I would reject the 7/5 split as unfair, because, conventionally, the expectation is that the return is proportional to the participation.

Consider an extreme sceanrio - $5990 and $1. As per the article the return should be $8999 and $3001. That's not going to fly in the real world.


> let's say the value is guaranteed to increase, in this example by 200% to $12,000.

Still kind of contrived:-(


The base case, in which Alice and Bob don't reach an agreement, has a specific name: BATNA. https://en.wikipedia.org/wiki/Best_alternative_to_a_negotiat...

Also note that it's two humans agreeing on a deal, and the way of looking at things described in the article might not be shared by both. If your other party is convinced that 6/6 is the most fair distribution, it is to your advantage to agree with that notion, at least if you are Bob. If you are Alice, then you should absolutely make the case. Of course if the game is repeated and you don't know the future game's distributions, this might come back at you, if the roles are switched and the other party goes into the game with that memory.


Another formulation (unless I misread the article and it's the same thing here) is the Shapley Value [^sv], where you divide up the extra spoils according to the value added by each agent. This works pretty nicely with high numbers of agents too, as well as makes sure it's in everyone's interest to join your sharing scheme even if they're not already in it.

[^sv]: en.wikipedia.org/wiki/Shapley_value


Yea, it seems the author is aware of it, covers it in the book[1], but decided against mentioning it in this article.

[1]: https://www.splitthepiebook.com/resources-2-1


This is not a new idea. It was written about thousands of years ago in the talmud: http://www.talmudology.com/jeremybrownmdgmailcom/2016/9/27/b...


Keep in mind this article is basically a Yale professor pitching their new book in an alumni magazine; not a great place for scholarly citations. Browsing the table of contents, the book itself has an entire chapter on this.


This example seem like a lesson for bob on how to not get screwed by Alice’s seemingly higher leverage by focusing on what is actually at stake to negotiate, the 6 extra slices. And also recognize Alice does not actually have more leverage just because the fallback is to her advantage, she would still have lost out up to 6 slices, making any type of deal would be better for her.


There is a whole book about this? The dark slices are each party's BATNA (best alternative to negotiated agreement, from Getting to Yes). Makes perfect sense that the negotiation is over the remaining pie


The point is that the remaining pie should be split evenly between the two parties, because they both have equal power in creating it.


In the simplistic example it could be argued that they have equal power. In a real scenario they likely don't.

In a real scenario, the dark slices may or may not be irrelevant; Bob must also consider making a deal with Charlie, who was left out of the example and has 6 dark slices of his own, or with David, who has 3 dark slices.

There is also the pizzeria across the street to consider which gives Alice and Bob each 3 dark slices.


I learned about this in the negotiation course [0] by Prof. George Siedel.

It is also called as BATNA - Best Alternative to a Negotiated Agreement (BATNA). This is evaluating what is your best alternative if the deal does not get through. In a negotiation, you would want to strengthen your BATNA and weaken other's BATNA. The course was amazing.

[0] - https://www.coursera.org/learn/negotiation-skills


This article is so infuriating I had to log in. All this article is underlined by the fact that Alice and Bob should try to get the most out of the negotiation regardless of needs. This is a rightist way of seeing the world, and in my mind childlike. With any level of maturity people should realize pizzas should be divided according to who needs it, whatever the definition of need is.

How about this way of dividing the pie: Alice and Bob describe theirs needs to a third party, and the third party gives each one what is needed. Or if no third party: just describe and justify your needs in an envelope, open both simultaneously, and share the pie.

The logic that "of course, everyone should take as much as they can" is an impasse. It doesnt make anyone truly happy, makes the person with the worse fallback an inferior to the other party during the negotiations, doesnt guarantee fairness, etc. And worst of all: it doesnt allow for human values such as empathy.

This article is an algorithm between programs, not any reasonable way to treat a person, valuing their feeelings and needs.


I grew up in a small village. I always like to think how my village would look when theories like these would be applied.

Would my village be a happier, better place if the one or two families who already own most land used it as an leaverage to extort as much resources as they could from the others? Quite definitly not.

The idea here is that the individual cannot trust the group to consider their needs. This is not a theory it is a collective lifestyle choice. There are countries and regions where the opposite (people looking out for each other depending on their needs) works out just fine.

In German we speak of something called the Gesellschaftsvertrag — the implicit contract each individual has with society. It can be extremely enlighting think about whether someone subscribes to this contract and if not, why. E.g. someone who has been convicted for years of prison for a minor drug charge while bankers who steal billions go free, might just stop to believe it pays off to honor the rules of the contract. Someone who thinks everybody else is just a fool to extract money from probably even thinks of society as something with implicit rules.

However every human society, even societies with slavery, genocide, etc had these implicit rules of what a wealthy person was expected to provide, what a poor person was expected to endure. Break the contract on a large enough scale and you get a violent change of power or a revolution.


I think the example problem has many issues with it which confuse the issue. There is a pervading assumption that more slices is better. What if Alice only wants 5 slices? Then her fall back is quite close to what she needs but also she doesn't mind how the pie is divided so long as she gets one slice.

It's not clear what everyone's utility function is. If a sales person is nearing a quarterly target, their utility function might have a giant kink in it, or if they're at the start of a period it might be very linear. The marginal pie, more often than not, has multiple dimensions which different agents care different amounts for.

Thankfully I've never been in a negotiation without a decent BATNA and so just chat about it until either we decide it's not going to work out, or we are both happy. People who negotiate too hard by playing stupid games and trying to max out themselves without any quarter given are tiring and push me to the first option. Why would I want to work with you if you're a pain to deal with before we even start?


Perhaps I got lost in the explanation, or the example is overly simplified, but isn't this just "splitting the difference"?


No. Splitting the difference could be a term invented to describe this, but it already has a different meaning. It's use is if I offer you two slices and you counter with a demand for six slices, then "splitting the difference" just refers to using the average value of four.


It is splitting the difference between Alice offering to take the whole negotiation pie at 10-2 and Bob counter offering to take the whole negotiation pie himself at 4-8.


Yes, if each originally maximally said "I want all 6 new slices" then it would be splitting the difference in their asks. However, in the case where Bob counters with an offer to split 6-6, it is no longer splitting the difference.


Now it has been bastardized by "Never Split the Difference" which is what you now hear from a desperate car salesman now


"Never Split the Difference" is also the name of an outstanding book by Chris Voss, the former head of FBI hostage negotiation. For shorthand, Voss refers to all biz school rational-actor negotiation theory (as espoused by the parent post, for example) as “splitting the difference.”

He holds that such theory is useful to know in general, but that real-world negotiations are carried out by emotional, irrational humans. As a result, these rational theories often break down in the face of hubris, anger, fear, love, shame, etc, and as such, relying solely on these theories will not get you the results you want. Thus, you should "never split the difference."

Instead, he then goes on to suggest a whole variety of ways one can achieve better negotiation results, starting with the most obvious: really, truly listening to the needs of the other. The book is fascinating. Highly recommended.


How would a desperate car salesman use that phrase?


The example is overly simplified.

Imagine if it was a 24-slice pizza. The argument is that the "original" 6 slices should be divided according to the original preferences of 4 and 2, and the "extra" 18 slices should be divided evenly into 9 and 9.


I imagine in many contexts, the more 'relative status-quo' outcome to the original would be 4+4 to 2+2, double-or-no-change. Bob wanting more than to double could be spiteful bargaining power which Alice could answer with spite.


I saw it in the article and literally thought it was a straw man. I believed the author was arguing against a 6-6 division and introduced a more unbalanced shift to try to make their position seem reasonable.

You're the first person I've seen suggest that this is a thing and I'm kind of shocked. What reasoning would there be for unequal division of the additional slices in A's favor?


It comes down to relative value of closing the deal. If both A and B want to increase their X, whatever it may be, an increase of 3 to A's 4 is not as much as 3 to B's 2 if we're talking about market share as an example. So already it's of more relative value for B to close the deal with +3's. Other factors apply. So it really comes down to how much each wants it, which is the status quo for negotiation. I don't think any business goes in saying "What's the fairest way we can make this deal?"

As an edge case, let's say A has 1M, and B has 1k and there's 500k new units. Should B get 250k same as A? Would A go for that? Would B be happy with 100k?


It's a modestly interesting point, but it certainly doesn't make sense in the concept of pizza. The author tries to appeal to fairness, but where the fallback positions are knowingly arranged randomly. Therefore, the naive 6-6 solution is just refusing to adjust for a superior random arrangement in the experiment, which was unfairly assigned. Therefore, I would expect the naive 6-6 to be chosen the plurality of them time.

There's also a question of if there is any value to clam pizza beyond the initial four slices. That sounds like a lot of food that reheats poorly.

Now, if you want to say this applies to something in the real world as a concept, I would say it's not a novel concept. No one expects a new employee to capture 100% of the value they add, nor do people expect the new employee to work for free.


Also, why is any pizza ever getting cut into 12 slices?


Aside from small pizzas, I generally cut pizzas into 12 pieces. 8 slices ends up with unwieldy slices, 16 makes for overly narrow ones. Cut it however you want, of course, but for most average sized pizzas 12 makes for a nice sized slice.


That’s very much a cultural thing. An average European pizza is more of a ‘personal’ pizza and 8 or 10 inches in diameter. Twelve slices would be too much.

I propose the Imperial/English pizza theorem. The optimal number of slices for a pizza is equal to the size in inches.


Unfortunately, that guarantees the arc length of the slice to be constant (at pi inches), but not the total area (= d * 1/2 in). I believe this is why larger pizzas make more sense to cut into squares, as long thin pieces are harder to slice and to eat.


Yeah, that's my exclusion for small pizzas. We only do personal pizzas for the kids. The rest of the family shares a larger one (or two, or however many).


A giant pizza cut so that each slice is a full meal (maybe two if very hungry) is optimal.Eating a slice of pizza should be enough.


If we can ignore the utility value of the negotiating pie (e.g. Alice may not want a 5th slice anyway), it is an interesting perspective. If only there were more examples and less explanation.


In general: Suppose the fallback positions are x slices for Alice, and y slices for Bob, and they get n slices total if they reach a deal. Then we can figure out the split by defining the gain, g, as the additional pieces they get if they reach a deal. So g=n-(x+y). Then the fair split should be x+g/2 for Alice and y+g/2 for Bob.

Another kind of situation is if there are 3 people, Alice, Bob, and Charlie, with fallbacks x, y, z respectively. Suppose they all need to reach an agreement to get n slices. Then g=n-(x+y+z) and Alice, Bob, and Charlie should get x+g/3, y+g/3, z+g/3 respectively.

Another possible situation is if there are 3 people, but they have unequal roles. Alice only needs to make a deal with at least one of Bob or Charlie, to get n slices. If Bob and Charlie both agree to the deal, then the total is still n slices. Intuitively, this would make Bob and Charlie less important, so they should get less of the gain. The split here should be x+2g/3 for Alice, y+g/6 for Bob and z+g/6 for Charlie, if they're all in on the deal. The reasoning there is that if we're adding games together, then we should also add the payoffs together. We can make a Alice&(Bob|Charlie) game by adding together Alice&Bob + Alice&Charlie - Alice&Bob&Charlie. Similarly, the payoffs should add like this: (g/2, g/2, 0) + (g/2, 0, g/2) - (g/3, g/3, g/3) = (2g/3, g/6, g/6)


Wow thanks for the very detailed explanation, mate, that is much appreciated. However, I still wish the author had delved into more real world examples, to let us have more sense of how this principle can be applied into more practical use cases. "Algorithms To Live By" https://www.goodreads.com/book/show/25666050-algorithms-to-l... did a really good job at that. Of course an article cannot be at book length but a man can hope.


I'd be curious how many people were surprised to be greeted by a picture of a pizza after clicking a link that refers to dividing pies.

I'm from California, where "pie" refers exclusively to the dessert variety. I expected the article wouldn't be specifically about pies, but rather about negotiation in general.

Did anyone (from areas where "pie" can mean pizza) think that this was going to be an article in which pizzas were used to illustrate the point?


Did anyone think to ask "who's hungrier?"


As you say, Alice is not in desperate need of pizza, so she’ll just wait for a deal that gives her the most. The power to say no to deals is the true advantage of greater wealth.


You assume Alice isn't the hungrier of the two and cares little for Bob's hunger, which sort of outlines my point: give more to who's hungrier.


Employee compensation would hilariously soar so much if this were the model. Currently employees in reality, are provided 0.00001% of the company.


> Currently employees in reality, are provided 0.00001% of the company.

0.00001% of Amazon's entire revenue (not profit, but revenue) last year would be about $14,000.

Fortunately, every one of their full time employees is paid more than that. Entry level engineers make 10X that amount and the best engineers make 50X that or more.

At some of the most highly paid companies like Uber, paying employees according to the value they create would actually make salaries go down in every scenario, because the company is still fueled by investor funds and can't self-sustain on revenue alone.

After round-tripping from IC to manager and back a couple times, I've come to realize that the value given to engineers especially is extremely high. Many initiatives in the tech industry don't ever turn a profit for the company or investors, yet we get paid six figures all the same.

If anything, I would expect such a hypothetical initiative to redistribute more of the wealth away from engineers like us and toward people like the customer support team who are fixing all of the problems created by products that don't work quite right. The person on the phone with grandma walking them through a support issue arguably contributes more to the LTV of that customer than anyone else.

Stepping outside of tech, I think people imagine profits to be much higher than they are in reality. Grocery stores are a common example of a business that has very narrow profit margins (some times a couple percent) that don't actually have large amounts of leftover profit to distribute to employees.

Regardless, it's all hypothetical. The employment market is supply and demand, and that's why engineers are paid so highly. End of story.


Salary is often the single largest expense on the income statement, and especially so for service based companies. This expense will frequently massively outstrip the profit line item. So no employees are not getting 0.000001% of these companies, they are in fact getting the majority of the money flowing through these companies.

You are noting that the employee line item is split up amongst 50,000 employees and the smaller profit number is behind split up among 50 owners. So an individual owner makes massively more money than an individual employee but missing that employees as a class are still getting more of the money than the owners.


I've always come to the same conclusion that "tit-for-tat" strategies are the simplest and most effective.

You agree to cooperate at the start. Then you follow whatever choice your opposition made the previous move. The even better approach is to add in generosity randomly as a means to "forgive" misunderstandings.

Maybe just me, but this article seems to add more complexity to the problem.


maybe a little off topic, but.... https://yaledailynews.com/blog/2021/10/14/yales-endowment-re...

I am thinking maybe t yale could spend a little time on finding a fairer way of slicing up that pie? It seems like they could easily educate a lot more people who cannot afford their tuition. And I am not just picking on Yale, Harvard and a lot of others could add to a fund, what if all those schools with multi-billions dollar endowments could give half of it to fund the education of anyone who wants it?

This is not a meant to be a rant just a humble suggestion that occurred to me when they were talking about giving away half a pizza.


Education doesn't scale. Great professors don't scale. The endowment is used for funding the tuition of people who cannot afford it.

And, to the degree it does scale (Edx, coursera) well endowed universities were at the forefront of putting classes online.


OK, so if I am understanding your point correctly, education does and doesn't scale, and big universities with huge endowments have done enough because they put classes online and subsidizes tuition for a small number of lucky people. So, it's OK for them to hold onto $42B endowment fund, for... something?


Some parts of education scale, some parts don't (see Customer Service and 100 other examples). Universities are doing a good job using tech to scale when they can. It's unreasonable to expect in person attendance to be able to even double and maintain close to the same quality.

Yale gives a scholarship to any students for the amount in between the expected family contribution and full cost of tuition/room/board/books/activity fees/small spending stipend. More than half of Yale students get such a scholarship and the average value of that scholarship is higher than tuition and books alone would be, meaning most students are only paying for housing and food. (Okay, it's an average and an average, so it's possible only like 40% of people are having their entire tuition covered, but also their entire room and board and another 17% are getting a dollar.)

But, yes. In general you summarized my points correctly. But I take issue to "small number of lucky people". And, of course, with the sarcasm clearly coming from your post.


OK, all sarcasm, set aside, will you divulge your relationship with Yale or other university with a large endowment? I sense some defensiveness.


Does it matter? Either you believe that they are giving away "enough" of their money, or you don't. If it's "don't" then it's unlikely that lack of a relationship will sway you, and if you do, then you'd want the argument to come from someone with intimate relationships to Yale (as you could then argue from authority).

More interesting IMO, is the question of whether or not great professors can scale, and whether online can do it. Or whether the real value add for "elite" universities is their quality of education, and whether great professors are required for it.

My beliefs (totally unfounded), is that yes, "great" professors _can_ scale, because the mark of the "great" professor would be their ability to explain things in lecture. This of course, ignores any personal attention you can glean, but for most undergrad courses you're not getting much of that anyways.


I guess another question is if great professors are only at Yale or Ivy league schools? Here's something to consider, maybe not everyone needs a great professor, or an elite education, perhaps there are a large number of people who could benefit from just a good college education without having gigantic debt after. Ivy league schools are sitting on nearly a trillion dollars in endowments half of that is enough to provide college for everyone who wants it. Maybe society would benefit more from everyone who wants college than a small number of elites getting ivy league degrees.


To respond in summary to all the posts - bfollis brought up a good point. I believe great professors do more than lecture. I can download the Feynman lectures (I believe they are still available), but I'll never be able to converse with him. But with a relationship with great professors you can. Or do some work in their lab. And that's the kind of thing that doesn't scale.

I don't think that great professors solely exist at prestigious schools, but there's definitely a greater density of them there. Just like FAANG has a greater density of competent programmers than competitors outside their tier.

I agree that not everyone needs a great professor. But, by definition, they are better. But yes, not everyone needs an elite education.

Ivy League schools have nowhere near a trillion dollars in endowment money. They have $1XX billion, I don't recall exactly how much.

I think that's all of the points, but I may have missed one.


https://www.forbes.com/sites/adamandrzejewski/2021/10/31/bal... Harvard tops $55B and Yale over $43B now.

I have listened to the Feynman lectures before, they are great for sure. But there are thousands of people haven't, and yet they still have benefited from a good college education.

If you want to figure out how to scale an elite Ivy league education, I think you cannot, I think the elite part is what trips you up. But if you want to see how to scale a good college education, you need look no further than the state university system, which for over 100 years has done exactly that. Unfortunately, the costs of that have gone up to the point that many young people are saddled with unmanageable debt. Some progressives, who are themselves the product of said elite education, talk about taxing billionaires and large corporations to pay for universal affordable college but somehow conveniently overlook the pile of money sitting in those endowment funds, far more than what those schools will ever need.

We should have universal affordable college for all that want it, billionaires and large corporations should contribute to that and so should the elite schools with outsized endowments. A good start would be to add a little tax to all those and increase the subsidies to state and community colleges.

And this comes from someone who is a product of said elite schools and was lucky enough to have it paid for. But not everyone is so lucky. I have also been lucky to have worked with young people who served their country and used those benefits to pay for college and, in my view, they are every bit as capable as anyone that attended an elite school.


Absolutely incredible! I haven't felt the feeling of insight after just reading 3 paragraphs in a long time.


Reading the title, I thought this will be about a fair splitting of home cooked pie (or any dish). My go-to method for this is to divide the responsibilities. One party cuts (or decides where to cut in the case children are involved), the other party picks. Does anyone use a better, fairer method?


For 2 people that's fair. It only gets a bit more complicated with more people or other variations.

https://en.m.wikipedia.org/wiki/Envy-free_cake-cutting


I'curious why the last time this appeared in HN it didn't receive a single comment. https://news.ycombinator.com/item?id=30140493


So... Uhh... Just Nash bargaining? Or Shapley values result in the same outcome too in this case.



The naive 6:6 split tries to compensate for the original unfairness. In real life, starting positions are mostly hidden and therefore this problem is avoided.


Duh. The hard part is that negotiators will lie to make it seem like the difference is smaller than it is.




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