Apr 27 JDN 2460793

In economics jargon, social preferences basically just means that people care about what happens to people other than themselves.

If you are not an economist, it should be utterly obvious that social preferences exist:

People generally care the most about their friends and family, less but still a lot about their neighbors and acquaintances, less but still moderately about other groups they belong to such as those delineated by race, gender, religion, and nationality (or for that matter alma mater), and less still but not zero about any randomly-selected human being. Most of us even care about the welfare of other animals, though we can be curiously selective about this: Abuse that would horrify most people if done to cats or dogs passes more or less ignored when it is committed against cows, pigs, and chickens.

For some people, there are also groups for which there seem to be negative social preferences, sometimes called “spiteful preferences”, but that doesn’t really seem to capture it: I think we need a stronger word like hatredfor whatever emotion human beings feel when they are willing and eager to participate in genocide. Yet even that is still a social preference: If you want someone to suffer or die, you do care about what happens to them.

But if you are an economist, you’ll know that the very idea of social preferences remains controversial, even after it has been clearly and explictly demonstrated by numerous randomized controlled experiments. (I will never forget the professor who put “altruism” in scare quotes in an email reply he sent me.)

Indeed, I have realized that the experimental evidence is so clear, so obvious, that it surprises me that I haven’t seen anyone present the really overwhelming knockdown evidence that ought to convince any reasonable skeptic. So that is what I have decided to do today.

Consider the following four economics experiments:

Dictator 1	Participant 1 chooses an allocation of $20, dividing it between themself and Participant 2. Whatever allocation Participant 1 chooses, Participant 2 must accept. Both participants get their allocated amounts.
Dictator 2	Participant 1 chooses an allocation of $20, choosing how much they get. Participant 1 gets their allocated amount. The rest of the money is burned.
Ultimatum 1	Participant 1 chooses an allocation of $20, dividing it between themself and Participant 2. Participant 2 may choose to accept or reject this allocation; if they accept, both participants get their allocated amounts. If they reject, both participants get nothing.
Ultimatum 2	Participant 1 chooses an allocation of $20, dividing it between themself and Participant 2. Participant 2 may choose to accept or reject this allocation; if they accept, both participants get their allocated amounts. If they reject, Participant 2 gets nothing, but Participant 1 still gets the allocated amount.

Dictator 1 and Ultimatum 1 are the standard forms of the Dictator Game and Ultimatum Game, which are experiments that have been conducted dozens if not hundreds of times and are the subject of a huge number of papers in experimental economics.

These experiments clearly demonstrate the existence of social preferences. But I think even most behavioral economists don’t quite seem to grasp just how compelling that evidence is.

This is because they have generally failed to compare against my other two experiments, Dictator 2 and Ultimatum 2.

If social preferences did not exist, Participant 1 would be completely indifferent about what happened to the money that they themself did not receive.

In that case, Dictator 1 and Dictator 2 should show the same result: Participant 1 chooses to get $20.

Likewise, Ultimatum 1 and Ultimatum 2 should show the same result: Participant 1 chooses to get $19, offering only $1 to Participant 2, and Participant 2 accepts. This is the outcome that is “rational” in the hyper-selfish neoclassical sense.

Much ink has already been spilled over the fact that these are not the typical outcomes of Dictator 1 and Ultimatum 1. Far more likely is that Participant 1 offers something close to $10, or even $10 exactly, in both games; and in Ultimatum 1, in the unlikely event that Participant 1 should offer only $1 or $2, Participant 2 will typically reject.

But what I’d like to point out today is that the “rational” neoclassical outcome is what would happen in Dictator 2 and Ultimatum 2, and that this is so obvious we probably don’t even need to run the experiments (but we might as well, just to be sure).

In Dictator 1, the money that Participant 1 doesn’t keep goes to Participant 2, and so they are deciding how to weigh their own interests against those of another. But in Dictator 2, Participant 1 is literally just deciding how much free money they will receive. The other money doesn’t go to anyone—not even back to the university conducting the experiment. It’s just burned. It provides benefit to no one. So the rational choice is in fact obvious: Take all of the free money. (Technically, burning money and thereby reducing the money supply would have a miniscule effect of reducing future inflation across the entire economy. But even the full $20 would be several orders of magnitude too small for anyone to notice—and even a much larger amount like $10 billion would probably end up being compensated by the actions of the Federal Reserve.)

Likewise, in both Ultimatum 1 and Ultimatum 2, the money that Participant 1 doesn’t keep will go to Participant 2. Their offer will thus probably be close to $10. But what I really want to focus in on is Participant 2’s choice: If they are offered only $1 or $2, will they accept? Neoclassical theory says that the “rational” choice is to accept it. But in Ultimatum 1, most people will reject it. Are they being irrational?

If they were simply being irrational—failing to maximize their own payoff—then they should reject just as often in Ultimatum 2. But I contend that they would in fact accept far more offers in Ultimatum 2 than they did in Ultimatum 1. Why? Because rejection doesn’t stop Participant 1 from getting what they demanded. There is no way to punish Participant 1 for an unfair offer in Ultimatum 2: It is literally just a question of whether you get $1 or $0.

Like I said, I haven’t actually run these experiments. I’m not sure anyone has. But these results seem very obvious, and I would be deeply shocked if they did not turn out the way I expect. (Perhaps as shocked as so many neoclassical economists were when they first saw the results of experiments on Dictator 1 and Ultimatum 1!)

Thus, Dictator 2 and Ultimatum 2 should have outcomes much more like what neoclassical economics predicts than Dictator 1 and Ultimatum 1.

Yet the only difference—the only difference—between Dictator 1 and Dictator 2, and between Ultimatum 1 and Ultimatum 2, is what happens to someone else’s payoff when you make your decision. Your own payoff is exactly identical.

Thus, behavior changes when we change only the effects on the payoffs of other people; therefore people care about the payoffs of others; therefore social preferences exist.

QED.

Of course this still leaves the question of what sort of social preferences people have, and why:

• Why are some people more generous than others? Why are people sometimes spiteful—or even hateful?
• Is it genetic? Is it evolutionary? Is it learned? Is it cultural? Likely all of the above.
• Are people implicitly thinking of themselves as playing in a broader indefinitely iterated game called “life” and using that to influence their decisions? Quite possibly.
• Is maintaining a reputation of being a good person important to people? In general, I’m sure it is, but I don’t think it can explain the results of these economic experiments by itself—especially in versions where everything is completely anonymous.

But given the stark differences between Dictator 1 versus Dictator 2 and Ultimatum 1 versus Ultimatum 2 (and really, feel free to run the experiments!), I don’t think anyone can reasonably doubt that social preferences do, in fact, exist.

If you ever find someone who does doubt social preferences, point them to this post.